Geotechnical Characterization and Modelling

Compaction control is the most significant factor affecting the behaviour of earthwork projects constructed with compacted fine-grained soils. The durability and stability of a structure are related to the achievement of proper soil compaction. Correlating engineering properties with index properties have assumed greater significance in the field of geotechnical engineering. In the present experimental study, an attempt has been made to establish the correlations between index properties of soils with the compaction characteristics of soils having different clay mineralogy altogether for varying energy levels. The compaction characteristics cannot be explained only by liquid limit and plasticity index of the soils but more effectively by plastic limit of soils. It can be concluded that these correlations can be used for predicting the compaction characteristics of soils in field compaction works.

The clay mineral-based soils having low permeability and high swell–shrinkage characteristics are preferred as a backfill and buffer material for containing hazardous waste. Though many factors influence the behaviour of these soils, the contribution of various particle sizes present in them is not thoroughly investigated. In order to examine the effect of particle size on electrokinetic, mineralogical and surface properties of soils, the selected soils were sieved through different size of sieves such as 75, 63, 54, 45, 36, 25 and 20 µm, and the fractions retained on them were collected. The collected fractions were processed and characterized for their electrokinetic, mineralogical and surface properties. Based on the experimental results, the role of different particle size on the micro- and macro-level behaviour of selected soils was quantified.

Geotechnical investigation of geomaterials is one of the most important tools to arrive at safe and economical design of structures. Inadequate investigations many times result in non-optimal geotechnical solutions. Encounterence of geological surprises and adverse geological occurrences result in cost overrun and sometimes even compromising safety of the structures. The Himalayan Mountains in Northeast India are quite young and have a large potential for hydroelectric projects. Since this area lies in seismic Zone IV, earth and rockfill dams are more suitable in this region due to flexibility of the materials and capacity to absorb vibrations. In the present study, 135 m high earth and rockfill dam at Tlawng H. E. Project, Aizwal, Mizoram, has been considered across river Tlawng. Three potential borrow area locations were identified near the dam site to meet the requirement of impervious material for clay core of the dam. Representative soil samples were collected from the respective borrow areas. Geotechnical properties of soil from three potential borrow areas were evaluated for suitability of clay core materials. A number of tests such as specific gravity, grain size analysis, Atterberg’s limits, compaction, chemical analysis, dispersivity test, one-dimensional consolidation, and triaxial compression test were conducted on the borrow area materials. The results of these tests indicate large variability in index properties and classification of all three borrow areas. However, variability is more or less similar in all three borrow areas. Based on results, it is concluded from the present study that excluding local pockets of soil which are non-plastic and highly compressible, most of the soil samples from borrow areas possess medium plasticity and impervious drainage characteristics, non-dispersive characteristics and exhibit good shearing strength. Based on the detailed investigations as discussed above, all three borrow areas are found suitable for construction material for core in earth and rockfill dam.

Coefficient of consolidation evaluated by different methods by considering different drainage conditions in the same soil could be quite different. Simulating field drainage conditions at the laboratory consolidation test may help to predict more accurate rate of consolidation. For conducting three-dimensional (3-D) consolidation tests, a 3-D consolidation apparatus is developed in which it is possible to perform consolidation test of soil samples under three-dimensional conditions. By using this apparatus, it is possible to simulate field conditions like pore water dissipation, and vertical and lateral strain of soil during the consolidation settlement. A comparison is established between oedometer test results and presently developed 3-D consolidation test results. By evaluating these test results, it is observed that the settlement characteristics measured by using the presently developed 3-D consolidation apparatus are more representative to the actual consolidation settlement in the field.

Grouting refers to injection of flowable stabilizers into a soil or rock formation to change its physical properties. The most important characteristic of grouting process is groutability, which is a ratio of particle diameter corresponds to 85% finer and 15% finer of base soil and grout material, respectively. Groutability is said to be very consistent if the ratio is high. However, the existing method to estimate the groutability may mislead the ratios as the conventional sieves may not represent the whole range of particle sizes available in the materials. Besides, state or density of the base soil is utmost important to estimate the groutability, especially if permeation grouting is considered. To overcome these disadvantages of the traditional methods, a new image-based method is introduced in the present study to estimate the groutability. Due to availability of promising imaging technics and latest advancements in image processing technics, an improved estimation of groutability is possible. Series of experiments were conducted on sand specimens at various depths to assess the groutability through imaging technic. Gradation analysis also has been performed to compare the data. The proposed new imaging technic has more promising information about the groutability than the traditional gradation curves. In addition to the time and energy consumed in traditional methods, the image-based method proves it highly accurate and simple than the traditional method.

In the present study, an attempt is made to evaluate the strength and dilatancy parameters of sands mixed with jute fibres. A series of direct shear tests were performed on sample of sands with mixture of 0, 0.25 and 0.50% of jute fibres at three different relative density states, namely loose, medium dense and dense, the effect of stress level is also bought out by varying the effective normal stress. The tests were conducted on dry sand having different relative densities (i.e. 20, 50 and 80%) subjecting them to different constant values of vertical normal stress ranging from 50 to 400 kPa. At each stress level and density state for each case of sand fibre mixture, peak frictional angle and dilatancy angle were found out by conducting direct shear tests. A series of the direct shear tests were conducted up to shear strain value of 40%. The stress-strain response was observed, and the shear strength and dilatancy parameters were obtained for sand–jute fibre mixture with each relative density and normal stresses. Also, a correlation between peak friction angle, dilatancy angle and critical state friction angle was obtained for sands mixed with jute fibre. The present data was also compared with those of the previous established correlations by Bolton (Geotechnique 36(1):65–78, 1986) and Kumar et al. (Indian Geotech J 37(1):53, 2007).

Soil classification is one of the most important stages in preliminary studies for analysis, design and applications in geotechnical engineering. The purpose of soil classification is to arrange various types of soils into groups according to their index and engineering properties and various other characteristics. Several existing agencies carry out the soil survey and classify the soil for different purposes. Fuzzy expert system is potent tool to mimic the human way of thinking and solve the problems dealing with uncertainty as they allow readable and interpretable rule bases. In this study, a fuzzy rule-based approach using fuzzy IF-THEN rules is used to quantify classification of soils in qualitative terms considering the index properties of soils. Triangular functions are used to fuzzify input properties of the soil to define the degree of membership. Fuzzy rules are generated to establish the soil types by aggregating fuzzified soil using the fuzzy operator. The experimental results are comparable with the outcomes of fuzzy system mode indicating the applicability of the developed fuzzy model for the engineering classification of soil.

The paper pertains to the determination of elastic and strength parameters of dry consolidated cemented mine tailing deep down a mine stope. The equipment used is a low-cost manually operated pre-bored strain-controlled small-sized pressuremeter (CAVITEX). Basic principles of the equipment are same as those of conventional pressuremeter as developed by Menard, but in contrast, the measuring probe has a single cell instead of tricell and the surface control unit is also different from those of conventional pressuremeters. This made the equipment lighter and easy to maneuver within the mine stopes located deep down (284 m) below the ground surface. A succinct introduction of the equipment has been given herein along with its operation and the theory used for estimating the tailing properties. The used equipment is robust, reliable, and easy to transport inside the mine. The test site conditions have been presented in the paper. The pressuremeter test results as obtained and the tailing parameters like the coefficient of lateral stress at rest, Poisson’s ratio, soil modulus like elastic modulus and shear modulus and the angle of shearing resistance as obtained, as computed are found to be reasonable. The studies showed that the method can be extended to determine the in situ properties of other geomaterials.

Steel slag is the granular by-product produced by steel manufacturing processes. In this study, the steel slag is evaluated using geotechnical and geo-environmental parameters to test its suitability for geotechnical applications. The electrical arc furnace (EAF) slag obtained from TATA Steel, Jamshedpur, is characterized by assessing its grain size distribution, relative density, specific gravity, short-term free swelling index, pH, and leaching characteristics. The slag is classified as silty sand (SM) as per USCS. The slag is reported as heavy material due to its high specific gravity. An appreciable amount of calcium concentration and highly alkaline nature of the steel slag submerged water were observed in this study. A small free swell index of steel slag was also observed in the investigation. This study reports high alkalinity, heaviness, and calcium leachability of steel slag as some of the hindrances for its utilization as geo-material.

Cone penetration test (CPT) is a very useful in situ test in offshore soil investigations for design and installation of important structures. The test makes it possible to acquire continuous data of soil below the seafloor. It is, therefore, used in almost all soil investigations for the development of offshore infrastructure related to hydrocarbon. Results from laboratory tests and CPT are complementary to each other and availability of both results increases the confidence of geotechnical engineers for assessment of soil parameters more reliably. CPT, where the pore pressure is also measured, is termed as piezo-cone penetration test (PCPT) or CPTU, where “U” stands for pore pressure measurement. Factors Nkt and N∆u are used for interpretation of undrained shear strength (su) of clayey soil from the test. The paper describes the process of calibration of the Nkt and N∆u factors using CPTU and laboratory data related to a site from Indian offshore. Further, relevant statistical parameters have been presented for both the factors.

Maximum shear modulus, Gmax (also called initial shear modulus), is an important parameter for offshore foundation design which is either interpreted from CPT using established correlations or derived from bender element or resonant column tests on high-quality retrieved samples in the laboratory. Since the reported correlations with CPT are area-specific, there was a need to develop such correlations for eastern Indian offshore also where big oil and gas field developments are being planned. Such correlations can help in optimizing the costly field and laboratory testing programs for future projects. The correlations also act as a check on the field and laboratory investigation results. With an objective to validate the reported correlations or develop new correlations, available CPT and laboratory test data on clays from shallow and deepwater areas of eastern Indian offshore were compiled and evaluated using correlations reported in the literature. This paper, after presenting the data, discusses the results of such evaluation and attempts to develop new correlations between maximum shear modulus derived from laboratory tests and CPT parameters.

Uncertainties in geotechnical engineering are unavoidable. The soil properties may distribute within a significant range over a domain. The soil is often very weak in tension and has less stability under heavy loading. This paper presents stabilization of soil with bottom ash reinforcement of soil with natural or synthetic fibers. Several reinforcing materials are available in the market, but they are costly and not easily accessible. Bottom ash (BA) was used as a stabilizing agent, and areca fiber was used for reinforcement, in this study. Polyvinyl alcohol (PVA), which is a synthetic fiber, was also used to compare the performance of areca fiber. As compared to fly ash, the use of bottom ash is minimal all over the world. This study determines the strength of the soil stabilized with bottom ash and fibers at different proportions. The percentage of bottom ash was varied from 0 to 40%; fiber proportion was varied from 0 to 2%.

Ballasted rail track system is one of the most important land transportation systems. Ballast aggregate is free draining granular material that helps to transmit and distribute an induced cyclic load to the underlying sub-ballast and sub-grade at a reduced and acceptable level of stress. Upon repeated train loading, ballast deteriorates and becomes fouled because of breakage and infiltration of external fine particles. It adversely affects the permanent settlement and strength of track. Geosynthetics are the most suitable method used to stabilize ballast track system. Performance of track is also depending on the strength of sub-grade soil. Main objective of the study is to investigate the load-settlement behaviour of ballasted rail track by using non-synthetic geocell with different pocket sizes placed above sub-ballast and sub-grade materials. The sand is used as sub-grade material. When placing 2D pocket size geocell above sub-ballast and sub-grade material, the settlement of ballast is decreased by 16.67% and 12.5%, respectively, and corresponding percentage reduction in ballast breakage is 50.46% and 44.7%, respectively.

Soil being particulate system encompasses a wide variety of particles, which has made it one of the most complicated natural materials to be modeled. Among soils, soft soil deposits pose challenging problems to geotechnical engineers for the assessment of reliable behavior of these soils to be used either as a foundation medium or construction material. In this study, nano-material additives have been chosen to investigate their influence on strength behavior of clayey soil. Two soil samples are treated with nano-material additives of nano-copper (CuO) and nano-gypsum (CaSO4·2H2O) at varying percentages of 0.5%, 1.0%, 1.5% and 2.0%, respectively. The test results revealed that the soil unconfined compressive strength increased significantly with increasing nano-material additives. However, the optimum value of nano-material additives content was observed around 1.5%. Therefore, the main goal of this study was to stabilize soft soil deposits for its bulk utilization in various geotechnical applications for sustainable environment.

The paper is mainly focused on the strain rate effect on shear strength of sands in direct shear test. Experimental investigations on two sands, one with rounded smooth grains (Ennore standard sand) and another with angular grains (Ganga sand), were carried out with a view to investigate the difference in shear strength of the sands at different shear strain rates. From the test results, it was found out that friction angle depends largely on gradation and particle angularity. Angular well-graded particles give the highest friction angle, and the rounded uniform particles give the least. Angle of shearing resistance increases with increasing the strain rate. For these two sands, relationships have also been established for prediction of peak friction angle as a function of relative density and rate of shearing strain.

Sand is a pervious material in nature, and bentonite has highly swelling and shrinkage property. Compacted layers of bentonite and sand mixes have been used in a variety of geotechnical structures. The objective of this paper is to investigate the strain rate effect on unconfined compressive strength (UCS) of compacted bentonite and sand (B:S) mixes. For this, bentonite of different proportions was mixed with 60, 70, 80 and 90% sand and the UCS of all the mixes with varying strain rate was determined. Three different strain rates—2 mm/min (fastest), 1.75 mm/min (medium) and 1.5 mm/min (slowest) were used in this study. Results indicate that for all the B:S mixes, the UCS increases gradually with increasing strain rate. The highest increase in UCS due to an increase in strain rate was observed for the mix B:S = 40:60. For all the strain rates, the UCS of B:S mixes increases gradually up to a bentonite content of 30% and further increase in bentonite content reduces the UCS of the mixes. Therefore, mix B:S = 30:70 can be considered as the optimum mix. The UCS of the mix B:S = 30:70 was found to be maximum when the highest strain rate of 2.00 mm/min was applied.

The amount of water associated with a given volume or mass of soil is a highly variable property. Determination of moisture content is most common activity in every soil testing laboratory as well as it has significance in field testing also. All index properties are having relationship with soil moisture content. Drying a soil to constant weight at 110 °C is the traditional method of arriving at a dry sample weight. This method required 24 hours of drying and soil containing gypsum and organic matter may require more drying period. Many other methods are also available as per Indian standards like torsion balance, radiation, pycnometer method, calcium carbide method and alcohol method. Some methods are also available such as, Proctor needle for field testing. But many of these methods are giving approximate water content and also having their own limitations regarding range of measurement. This study aims at rapid and accurate determination of soil moisture content of sample by using moisture sensor. It can save time as well as provide required accuracy in laboratory and field testing.

In the present investigation, a series of finite element analysis has been carried out on anchor with tie embedded in sand by using the finite element-based software “ABAQUS.” Bell-shaped anchor with bell diameter 0.125 m has been used in the present paper for analysis purpose. Results are obtained from the numerical analysis, and it is found that with introduction of geotextile tie to the anchor the ultimate uplift capacity increases. From the analysis results, it is also observed that the optimum values of length of geotextile tie-to-anchor bell diameter ratio (Lg/D) is 3.0 within the range of embedment depth-to-bell diameter ratio (H/D) of anchor 1–3. However, for H/D = 0.5, the optimum value of Lg/D is 4.0. The frictional efficiency as well as angle of internal friction does not have much influence on optimum value of Lg/D ratio.

Controlled low strength material (CLSM) is a self-levelling and self-compacting material that is used as a backfill material in place of compacted soils. Flowable fills require no tamping or compaction to achieve the strength. Various CLSM mixtures were prepared by using fly ash, quarry dust, blast furnace slag and cement. For all the mixes, the cement content is kept constant at 5%. The amount of mixing water is chosen in order to provide a flowability value of 250 mm. The mixtures are inspected for series of tests in fresh state and hardened state. Properties like flowability, bleeding, fresh density and compressive strength are studied. Apart from the short-term performance, long-term performance of CLSM samples is studied by conducting durability test. The results indicate that the replacement of fly ash by quarry dust or blast furnace slag showed satisfying performance and developed CLSM are suitable for various applications.

In this paper, 3-D finite element simulations are carried out to investigate the effects of certain geometric parameters of pile on the performance of piled raft under vertical load. Finite element (FE) modelling-based package PLAXIS 3D is incorporated to carry out the analyses of piled raft foundations embedded in sand. A calibrated FE model is used for the parametric study by varying the geometric parameters of pile, i.e. normalized pile spacing (S/d = 2, 4, 6) and normalized pile length (L/d = 20, 40, 60) under the raft. The diameter of the pile ‘d’ is considered 0.5 m. In this study, results are presented in terms of a dimensionless quantity, namely bearing pressure improvement (BPI). It is observed that that the bearing capacity of piled raft increases with increasing pile length and spacing between them. The BPI is found to increase more when pile spacing (S/d) changes from 2 to 4 as compared to the case when it changes from 4 to 6. The overlapping of pressure bulbs of the piles is found to cause higher settlement and hence lower bearing capacity of piled raft system.

In the present study, the interference effects of two closely spaced strip footings on the surface of stiff clay were investigated. The effect of interference on characteristic behaviour like bearing pressure, settlement and tilt is observed using two-dimensional plane strain analysis. Finite element analysis software PLAXIS 2D is used for this. The behaviour of individual footing on stiff clay is first established. Parametric study is done by varying the width of footing and the spacing between the footings. The results are presented in terms of efficiency factors, which are defined as the ratio of settlement or bearing pressure of interfering footing to that of the isolated footing. The effect of interference is particularly noticeable in terms of settlement. Maximum settlement and tilt occur at a spacing 1.5B irrespective of the footing width. Effect of shear keys placed beneath the footings at different locations beneath the footing and the interference of such footings were also studied. It is found that the presence of shear keys has a significant effect on the interference between the footings, compared to without the shear keys.

In this paper, an analytical and numerical study is presented for the slope considering bamboo piles as reinforcing material. The analytical solution was formulated using modified ordinary method of slices. Bamboo piles were considered as vertical reinforcements in the slope along the length of the slope having uniform spacing between two adjacent piles. Based on the equilibrium conditions, three cases of failure were considered. Equations for calculating factor of safety (FOS) were formulated using ordinary method of slices for each case considering the effect of bamboo reinforcements. A case study was also performed to investigate the effect of bamboo reinforcements on stability of the slope. From the result, it is concluded that the factor of safety increased significantly after including the bamboo piles as reinforcements. The number of bamboo piles can be designed based on the requirement using proposed analytical equations. Thus, bamboo pile can be reliable and can perform satisfactorily in stabilizing slopes.

Slope stability analysis is of particular significance to geotechnical engineers for construction of railway embankments, canal, road embankments, earth dams, etc. Slope failures can have devastating social and commercial impacts. To assess the safe design of slopes, factor of safety values acts significant roles. Factor of safety values is used to define how close or far slopes are from failure either occurring naturally or induced by manmade activities. Traditional limit-equilibrium method is the most common technique for analysis of slope. In recent times, finite element method (FEM), a powerful, viable alternative technique is available to the geotechnical engineers. In the present investigation, an attempt has been made to study the analysis of slope based on the numerical simulation using Geo-studio software. The parameters of soil strata constituting the slope are determined from laboratory results. The main objective of the present study is to indicate the correlation between factors of safety of embankment using different approaches, e.g., analytical approach and analysis as per “Guidelines for Earthwork in Indian Railway Projects” with finite element modeling. Finally, the paper presents the correlation between the slope angle and factor of safety for cohesive and cohesionless soil.

The principles of slope stability analysis embrace the mechanics of slope failure to develop methods of stability analysis, to predict factors of safety and corresponding slope movements. By equating the disturbing and resisting forces on potential slip surfaces, limit equilibrium method computes the corresponding factor of safety. These static stability methods can be used to calculate the minimum factor of safety, but they cannot predict pre- and post-failure movements of the system in case of failure. As an advanced numerical method, finite element method and the strength reduction technique take into consideration the stress distribution within the slope. This stress distribution controls the deformations, movements, and development of failure zones for a given slope. Along with the factor of safety, FEM also predicts these expected deformations/movements. These deformations in FEM are dependent heavily on the meshing of the whole system and suffer from mesh distortion and low accuracy in case of run-out/flow analysis where mesh deformations are relatively more significant. Run-out/flow failures (landslides, landfill failures), where the debris flows over a great distance, have been a prominent research topic for many years. Numerical methods have been developed such as the center of the mass method, FEM with updated mesh techniques, DAN/W, and meshless methods (SPH, DEM, and DDM). Smoothed particle hydrodynamics (SPH) is a meshless technique which discretizes continuous material into discrete particles. When combined with yield strength, SPH solves Navier–Stokes equations to predict the slip surfaces as well as run-out/flow of the slope. In this study, a comparison has been made between LEM, FEM, and SPH on slope failures taken from literature. The slip surfaces as obtained from these slope failures have been compared, and the deformations have been studied between FEM and SPH. The advantage of SPH in predicting flow failures has been highlighted.

A 2D finite element analysis was conducted to obtain the factor of safety against deep-seated failure of embankments resting on granular columns. Two methods, namely individual column method and equivalent area method, are used to compute the safety factor (FOS). The results of the parametric analysis with the prime factors that influence FOS say the undrained cohesion of soft deposit, friction angle of the granular column and embankment, the height of embankment, groundwater table variation have been examined. The comparative study shows that the individual column method yields a slightly high safety factor over the equivalent area method. Nevertheless, the equivalent area method is a quick, easy method to obtain a factor of safety which speaks on the overall improvement of the homogenized ground. Additionally, a reduction factor was proposed to account for the difference in FOS when individual column method is converted to equivalent area method.

The use of geosynthetic-filled systems like bags, mattresses and tubes for slope protection/stabilization works has gained popularity in recent times due to its inherent flexibility and durability. This work evaluates the performance of slope strengthened with grout mattress under seepage condition with the aid of centrifuge modelling. For this, centrifuge tests were performed at 50 gravities using a large beam centrifuge available at IIT Bombay on slope models with and without grout mattress, under steady seepage conditions. The tests were carried out on two model sets: (i) GMS1—unstrengthened slope, (ii) GMS2—grout mattress-strengthened slope without toe drainage, while maintaining a constant slope angle of 45°. The test results showed that the grout mattress-strengthened slope (GMS2) performed better than the unstrengthened slope (GMS1), which registered a catastrophic failure. Thus, grout-filled mattress with proper drainage provisions could be considered as a viable slope stabilization method especially for landfill slopes, ash pond dams and river training works.

Rainfall-induced landslides occur on soil slopes due to seepage of water through the interconnecting voids down the soil mass. Vegetation on the slopes is depicted to have hydrological properties that deplete the excessive soil moisture for photosynthesis, translocation, transpiration and structure. Contrarily, these roots present in the soil, forming a preferential flow path, and allow the seeping water to reach greater depths. Different plant species have different root network characteristics which have been studied earlier. The current paper portrays the laboratory study on effect of two different plant species, namely Deodar (Cedrus deodara) and Ritha (Sapindus mukorossi), on the permeability characteristics of soil and their relationship with root network characteristics. The results show that the presence of plant roots increases the permeability of soil mass. This study could be helpful while selecting the plant species and their positions on a slope for the purpose of achieving soil stability.

In ground improvement techniques like micropiles, soil nailing, jet grouting, and reinforced earth structures, the values of skin friction and shearing resistance between geomaterials and construction materials are considered in their design. However, it is very essential to estimate the stresses transferred along with the interface between geomaterials and reinforcement. Also, in the context of the study of debris flow after a landslide, the interaction between the debris and the surface material is crucial parameter to estimate the transportation parameters of debris material. When stress component is important for earlier studies, strain marks its importance in that of the later. Though the vast literature is available on the stress phenomenon, limited scope has been depicted on the strain parameter which is equally important. Hence, the present study aims to investigate the interfacial studies between soil and various textured surfaces and understand the interface behavior. The textures have been mimicked resorting to abrasive papers on a wooden block.

Cantilever sheet pile walls are generally used to retain limited height of excavation (≤5 m) in both cohesive and cohesionless soil as a temporary or permanent structure. In actual practice, sheet pile walls are subjected to surcharge loads in the form of permanent buildings, vehicles and others. Hence, keeping this in view, in the present study, a numerical investigation is carried out for a strip load as a surcharge acting on the backfill of the cantilever sheet pile walls by varying the width of strip load and its distance from the top of the wall. From the results, it is observed that placement of strip load away from the wall changes the bending moment along depth and settlement of backfill significantly. A critical width of strip load b = 3 m at the top of the wall is observed for maximum bending moment along the depth.

The present study focuses on the release of dark-colored leachate from soil-like material (SLM) reclaimed from aged municipal solid waste (MSW) at three dumps of India (located at Delhi, Hyderabad and Kadapa). If the material is to be used in filling low-lying areas or in embankments or subgrade, the leaching of colored liquid can cause coloration of the surrounding water bodies and groundwater. Local soil was used as a base material for comparison of release of color. Mined soil-like material from MSW releases dark and objectionable color of leachate. The intensity of color of leachate from mined SLM is found to range between 380 and 400 Hazen, 460 and 480 Hazen and 900 and 1000 Hazen in the samples from Delhi, Kadapa and Hyderabad landfill, respectively. In contrast, the intensity of color in water released from local soil varies between 25 and 30 Hazen. The study concludes that small amount of mined SLM requires large quantity of water (70–100 times) for washing the material before the intensity of color reduces to acceptable level, thereby demonstrating the potential to significantly impact nearby groundwater wells. Thermal treatment is observed to be reducing the color to acceptable level before reuse.

Chilika Lake is the largest coastal lagoon in India. The geomorphology, water quality and biological productivity of the lake had undergone significant changes over the years under the influence of natural events and anthropogenic interventions with loss of biodiversity due to silting up of the outer channel. The Chilika sand is poorly graded sandy soil with 80.1% of fine sand and 19.7% of medium sand with a specific gravity of 2.64, the optimum moisture content of 10.3% and pH 7.72. Two biopolymers, guar gum, and xanthan gum are used to stabilize the sand imparting shear strength of sand which can be used to make small (dumps) islands for the migratory birds. Better surface penetration force with guar gum solution obtained with 0.5%, 1%, 1.5%, 2% are found as 70.19 N, 72.28 N, 66.99 N, 18.76 N, respectively. The UCS values are found for guar gum with 246 kPa, 334 kPa, 419 kPa, 547 kPa for 0.5%, 1%, 1.5% and 2% guar gum, respectively, after 60 days. Hence, use of biopolymer for stabilization of sand can be used as the barrier in the lake for sustainable development of the fragile ecosystem.

This paper presents the effects of the two commonly employed gripping systems in geosynthetic–geosynthetic interface shear testing using a 300 × 300 mm direct shear device, in accordance with the ASTM D 5321/D 6243 test method. Currently, gripping systems vary widely among laboratories and the preferred surface remains a topic of debate. In this study, the nail plate and sandpaper were used, and their shear stress–displacement curves obtained from the geotextile/geomembrane and geomembrane/geosynthetic clay liner interface are discussed. The results revealed that the nail plate was the most effective gripping surface for geotextile/geomembrane interface testing, whereas the sandpaper was suitable for geomembrane/geosynthetic clay liner interface testing tested at normal confining pressures of 200 kPa and higher.

Bamboo is a natural reinforcement material, manufactured by bamboo strips, and has been accepted as a substitute to geogrid for reinforcement applications, due to its tensile strength properties. An effective use of the bamboo grid depends upon their configuration of mats. This paper presents the results of interface friction parameters between the bamboo grid of different opening sizes and sand. Three bamboo grids of different square opening size 10, 15 and 20 mm with sand were used in this study. Another bamboo grid of the hexagonal opening was used to compare the effect of aperture shape on interface shear strength parameters. Large size shear box of length 300 mm, width 300 mm and height 200 mm is used. The shear strength parameters of sand were tested in large direct shear apparatus with and without bamboo grid. The test results indicate that the tridirectional bamboo grid provides better performance than the bidirectional bamboo grid reinforcement.

There are many parameters, which affect the dynamic response of structures, such as the type of structure, type of foundation, soil characteristics, etc. In this paper, soil-structure interaction in the analysis and design of reinforced concrete framed buildings has been investigated using SAP2000 vs16. Base shear, bending moment, deflection and natural period of multi-storey buildings with raft foundations, having different height to width ratios, resting on different types of soils, and subjected to a seismic ground motion were studied using Gaussian process regression (GPR) and least-square support vector machine (LSSVM). The ground motions were selected from the data of the Bhuj earthquake of 2001. A comparison of the performance of the GPR model and LSSVM model has been done based on Probability Distribution Function (PDF) and Cumulative Distribution Function (CDF).The results showed that the developed bending moment model was found more efficient compared to base shear and deflection models.

Seismic response evaluation of the site of interest subjected to a particular bedrock motion is one of the most important problems in earthquake geotechnical engineering. A stress–strain relationship is needed in a complete nonlinear time-domain site response analysis. Mostly used, Massing rule does not incorporate asymmetric behavior of the soil. Researchers had showed that the hysteresis loops become progressively asymmetric with increasing shear strain. Most of the available stress–strain relationships provide greater hysteresis damping for medium to large strains compared to the damping values obtained in dynamic tests. In the present study, a Bouc–Wen class model is proposed to capture the asymmetric behavior of soil at high cyclic shear strain. The model parameters are calibrated against cyclic triaxial experimental results of saturated sand available in literature. The calibrated model could successfully capture the stiffness decay, loss of strength and asymmetric behavior of saturated sand for higher cyclic shear strain.

The recent studies focus on the sand and rubber tire shred mixtures for their application as seismic base isolation of buildings. The dynamic properties such as shear modulus and damping ratio of these materials are very important for the seismic soil-structure analysis. Cyclic triaxial testing is widely used to determine the large-strain dynamic properties of soils. However, the cyclic triaxial tests do not represent realistic stress conditions during the ground motion. The cyclic simple shear tests which best represent in situ seismic stress conditions are mostly used for liquefaction assessment and seldom used for finding the dynamic soil properties. The size of the specimens used for both types of tests is dissimilar and hence is presumed to have an effect on the shear modulus and the damping ratio. This study highlights the possible effect of specimen size on the dynamic properties of the river sand and rubber tire shreds and an optimum sand–rubber tire shred mixture obtained from the cyclic simple shear tests and cyclic triaxial tests.

The present research focuses on the compressive strength characteristics of colloidal silica-stabilized sand in comparison to that of untreated sand of similar relative density (55%). Specimens were prepared in the laboratory by treating sand with different weight percentages of colloidal silica solution. The research on the soil improvement with the addition of colloidal silica is slowly yet increasing day by day due to its mechanical stability with respect to most other chemical grouts. Colloidal silica is also nontoxic, biologically and chemically inert, and has excellent durability characteristics. The sand specimens stabilized with colloidal silica were cured for seven days. It was observed that stabilized sands showed a significant improvement in strength and static loading. This paper is also an attempt to review the technical benefits and feasibility of applying colloidal silica gel as grout in soil stabilization. A number of laboratory unconfined compressive tests and unconsolidated undrained triaxial tests were performed in order to evaluate the shear strength and compressive strength of sand-grouted colloidal silica gel.

Mapping and identification of soil layers and rock profiles is an essential task in any geotechnical engineering project. Conventionally, these are accomplished by conducting standard penetration test (SPT), which are time consuming, expensive and requires skilled workmanship for execution. On the other hand, development of various geophysical methods like Spectral Analysis of Surface Waves (SASW), Multichannel Analysis of Surface Waves (MASW), etc. is very much helpful to map and identify the soil and rock profiles as well as the in situ dynamic properties. MASW is a seismic method that uses surface waves to estimate shear wave velocities (Vs). The main motivation behind this experimental study is to study the efficacy of MASW survey for delineating the soil layers and rock profiles. In addition to that, measurement of Vs profiles at various depths in a construction site is also conducted. The results of MASW survey are then cross-verified with SPT profiles.

The support pressure offered by means of lining for maintaining the stability of a square tunnel driven in a layered clay medium under undrained condition has been determined. Finite element lower bound limit analysis and linear programming are used for performing the analysis. The support pressure is assumed to be uniform on the periphery of tunnel. The influence of undrained shear strength of upper layer relative to that of lower layer on the magnitude of support pressure has been studied. The magnitude of support pressure required to maintain the stability in the layered clay medium as compared to that of homogeneous clay layer has also been examined. Corresponding to a given cover of the tunnel, the magnitude of required support pressure is found to be decreasing continuously with an increase in the ratio of undrained shear strength of upper clay layer to that of lower clay layer.

Rock mass in nature is generally heterogeneous and anisotropic. Due to this, the variation in engineering properties of the rock mass is quite high. The engineering behaviour of rock mass depends on several factors, and sometimes, the evaluation of these factors is quite complex. Hence, probability-based approaches are used for prediction of engineering properties of the rock mass. Probabilistic analysis is a powerful tool for analysing the inconsistent data and predicts the behaviour of materials. With the help of probabilistic analysis, a solution of varying data can be obtained which may be used in the design and analysis of rock structures. The possibility of failure of structures built in rock mass can also be predicted using probabilistic analysis. Prediction of engineering properties using probabilistic analysis is summarized in the present paper. Borehole data were collected from a project site in the Himalayan region of northern India. The rock mass exposed at the site consisted of genesis with some bands of quartzite and phyllite. The borehole was drilled in vertical direction up to 127 m from ground surface. The average diameter of collected cores was 54.8 mm (NX size). From these cores, RQD and joint characteristics (JCS and JRC) were estimated. Uniaxial compression tests were also conducted on some specimens to increase the accuracy of data. Probabilistic analysis was performed with collected data sets. The results were analysed, and probability-based prediction of RQD, UCS and joint characteristics have been made. The main advantage of this analysis is that for any chosen value of probability, evaluation of these parameters can be easily made which helps in predicting the possibility of failure of rock structures.

Tunnel plays a vital role in our way of life as it eases the method of the transportation. Lining is the necessary permanent ground support system to the periphery of a tunnel or shaft excavation, and/or the material installed in the position with an inner surface suitable for the specific end use of the underground excavation. Lining of tunnel is technically an important component and generally constitutes 30–40% of the total cost of the tunnel. Therefore, lining operation requires considerable study and careful planning. Due to complexity of various problems in engineering field, finite element analysis [FEA] is widely used. It divides the domain of the problem into several sub-domains; thus, it is easier to solve the complex problem. In this paper, cut-and-cover canal tunnel lining subjected to gravity load, horizontal and overburden pressure using FEA-based software “GTS-NX”, the thickness of the tunnel has been designed, and the result is compared with USBR method. Thickness of tunnel lining for lower overburden loading over crest in both the analysis is same, but for higher overburden loading (8 and 11 m), thickness is slightly less in GTS-NX than USBR monogram method.

Open cast mining has grown at phenomenal rate in India because of increasing demand for energy. Open cast mining has raised to 250 million tonnes which represents 70% of overall coal production. This type of mining differs from extractive methods that require tunneling into the earth, such as long wall mining. These mines were used when deposits of commercially useful ore or rocks are found near the surface, i.e., where the overburden soil is relatively thin or the material of interest is structurally unsuitable for tunneling. In this paper, geotechnical properties of overburden soil are determined. Soil samples are obtained from Gouthami open cast mines at depths of 50, 100, 150, and 200 m to assess the depth-dependent behavior of soil. Samples are tested for particle size analysis and compaction properties. Compaction curves indicate that optimum moisture content varied from 10.8 to 13.3% along with depth. The dry density of soil is varying from 1.96 to 2.03 g/cc.

Tunnel design in a weak rock is very difficult for the geotechnical engineers. Rock shows some special characteristics and challenges for the geotechnical engineers due to which wrong estimation in the support design may lead to costly failures. Therefore, it is very much essential to understand the problems involved for designing of tunnel support system in weak rock. It is also necessary to inspect rock mass deformation behavior thoroughly, before the tunneling work progress. In our study, the support system of a tunnel in weak rock is designed by using two methods: (i) empirical method using RMR, RMi, RQD, GSI and (ii) numerical method using Phase2 finite element analysis. As the conventional empirical methods cannot provide an appropriate estimate of the support performance, stress redistribution and deformation around the tunnel and use of numerical method such as finite element method could be a better and appropriate solution. Field data were obtained from the literature and used as input for both analyses. For the simulation purpose, three-types support system was considered in this study for tunnel design. These are (a) unsupported, (b) shotcrete and (c) rock bolt and shotcrete used together. The simulations and analysis were carried out to obtain the stress distributions, displacements and yielded elements, using the Rocscience Phase2 software. The results obtained suggested that the combined application decreased the deformation and yield of the elements throughout the tunnel. The results suggested that the proposed support system analyzed by both empirical and numerical methods could provide safe design of tunnel.

Construction and demolition waste (CDW) consists of debris generated during the renovation or development of structural elements. Rapid urbanization renders it necessary to reduce the consumption of non-renewable natural resources drastically and also to limit the dumping of these materials after the expiration of their service life. In a rapidly progressing country like India, development of infrastructure produces a lot of solid waste. This derives the interest to reuse it by admixing or adding with existing soil to improve its strength properties. The concrete and brick content, which constitutes a major portion of CDW, is called as building derived material (BDM). The shear strength of soil partially replaced with BDM is a significant property that defines its suitability for several applications. However, it is not an intrinsic property and varies with several experimental factors such as relative density of soil and shearing strain at which shear tests are conducted. The present study deals with the behavior of BDM when admixed with locally available red soil tested at different strain rates (1.25 and 2 mm/min). Consolidated undrained triaxial tests are carried out at three different confining pressures (100, 150, and 200 kPa). This study further investigates the effect of the degree of compaction on the shear strength properties of soil–BDM blends. The results obtained from this study show that the addition of BDM to the soil is enhancing the resistance of the soil to deformation under axial load.

Retaining walls, deep foundations, and reinforced soil/nailed structures involve interaction between structural elements and soil. Experimental investigation of interface characteristics such as adhesion, the angle of interface friction, compression/dilation behavior, and normal and shear stiffness forms an essential prerequisite in the design and numerical modeling of these structures. In the present work, direct shear tests are conducted to quantify the shear strength and interface characteristics between two soils, namely red clayey sand and black clay in contact with different continuums such as cement mortar, steel, jute geotextile, woven, and nonwoven geotextile. Direct shear test is conducted with one half of box filled with soil and contact with a structural surface glued to a wooden block placed in the other half. The ratio of interface friction angle to the internal friction angle of soil ranged from 0.73 to 0.95 depending on the roughness of the surface. Volume change of soil depends on the roughness and hardness of the continuum surface. Vertical inclusion of reinforcement in soil increased the shear strength of soil from 11 to 39%, and the improvement in shear strength of soil depends on the extensibility of reinforcement and its resistance to rotation.

In this study, the influence of glass fibre reinforcement on the strength and deformation performance of a cohesive soil is investigated by conducting a series of consolidated undrained triaxial tests. The specimens were reinforced with 10 mm fibres of four different contents. Test result shows that the glass fibres have significantly improved the stress–strain, shear strength, secant modulus and energy absorption capability (EAC) which further increases with increasing confining pressure. With increasing fibre content, the positive pore pressure development increases and bulging of specimen decreases. Contribution of fibres in deviator strength ratio (DSR) is higher at low confining pressure and decreases with increasing confining pressure. However, the fibre contribution on secant modulus and EAC increases with increasing confining pressure. Both cohesion and friction angle have increased with fibre content and the maximum fibre contribution is found with 0.75% fibres. The glass fibre-reinforced cohesive soil has ample scope for various geotechnical applications.

Geopolymer is an inorganic polymer formed by alkaline activation of fly ash. Inertness in excess can neither be digested by nature nor stop itself from being hazardous, and fly ash is one such inert material whose count in the environment is increasing exponentially each day. In the present study, fly ash from Kakatiya Thermal Power Station is deployed in the form of geopolymer for boosting the strength of locally available weak soil. The quantity of polymerization is a function of alkali/ash ratio, sodium silicate to sodium hydroxide ratio and percentage of fly ash. The strength of the soil by the fluctuation of those parameters was studied. The strength and durability of geopolymer-stabilized soil with escalating fly ash percentage are compared with virgin soil sample by using unconfined compression strength test and wetting/drying test. The maximum strength of soil is achieved at 0.6-alkali/ash ratio, an optimum fly ash percentage 30% and liquid ratio 1. In addition, soil survived for 12 cycles of durability test.

In this era of modern time where due to rapid growth in population, expanding industrialization etc., within the same limited resources including the land resources enforces the mankind to use the land resources in an economical manner, leading to demand of use of areas having soft soils, dumping places, wetlands, landfill sites (after closure) and even to go for vertical expansion rather than horizontal in terms of multistory buildings, tall structures etc., leading to imposition of huge loads, which cannot be supported by the existing soil at such places. So as a ground improvement measure, the present paper focuses on introducing stiffening effect in the top region of the granular pile. Stiffening means replacing the conventional material of the granular pile in the top region up to a certain depth that is why calling it partial stiffening, by a material having better mechanical properties and thus not only providing the solution to the problem of bulging but also increasing the load-bearing capacity by reducing the settlements. Analysis of a partially stiffened group of two granular floating and end bearing granular piles has been numerically assessed and presented here. Normalized parameters like shear stress distribution along soil–granular pile interface, axial load distribution along soil–granular pile interface and percentage load transferred to the base are evaluated. The shear stresses are found to reduce at the top of GP in a group of two GPs and are transferred toward the base of the GP.

Flowable fills, also called as Controlled Low Strength Materials (CLSM), are often used as alternative to compacted granular materials in specific situations like bedding layer to buried pipelines and backfill behind retaining walls. The fills are widely used in places where compaction cannot be done due to inaccessibility for moving compaction equipment and are often subjected to cyclic loading. While several studies are available in the literature on the static behaviour of flowable fills, the cyclic behaviour of flowable fills received less attention. This paper focuses on the cyclic behaviour of pond ash-based flowable fills. Comparative studies were carried out on compacted pond ash (CPA) specimens prepared at both standard and modified Proctor unit weight and optimum moisture content for similar testing conditions. The cyclic behaviour was studied by performing cyclic triaxial tests for different cyclic stress ratio (CSR) on both compacted pond ash and flowable fill. The results obtained based on cyclic triaxial tests showed that the flowable fills perform much better compared to the compacted pond ash specimens.

The objective of this study is to determine the result of variation of soaked and un-soaked CBR values, obtained from the silty-clay soil mixed with fly ash as well as sand, with time. Fly ash or sand is mixed to the soil in the percentages of 10, 20, 30, 40, 50 and 60% by dry weight, individually. Modified Proctor compaction is adopted in this study. The samples are compacted at OMC, OMC + 2% and OMC – 2% and kept for 0, 4, 10, 15, 20 and 25 days under both soaked and un-soaked conditions. An addition of fly ash and sand increased the soaked and un-soaked CBR value of the soil even after 25 days, but sand showed better results of CBR. The samples exhibit better results of CBR on the mixes compacted at water content OMC – 0.2% also. Therefore, it can be said that both fly ash and sand are conformable to be used in the improvement of CBR values of the silty-clay soil even after long period of times.

Bottom ash is one of the major industrial wastes coming out of the thermal power plants in huge quantities, while on the other hand, disposed polyethylene terephthalate (PET) bottles which are used for bottling mineral water/soft drinks and discarded after use are also causing huge environmental problems. Use of this non-biodegradable waste as soil reinforcement along with bottom ash may help in solving the problems of their disposal and environmental hazards. Keeping this in view, a series of model footing tests were conducted to investigate the response of square model footing supported on bottom ash reinforced with multilayered geocell mattresses made up of waste PET bottles. The influence of number of geocell layers, width of geocell mattress and aspect ratio of unit cell was studied. The results revealed that insertion of multilayered geocell-reinforced bottom ash in the subgrade results in a considerable improvement in the load bearing capacity.

This paper presents the shear behavior of unreinforced and geogrid-reinforced fresh and soil fouled ballast based on large-scale direct shear tests. Fresh granite ballast with an average particle size (D50) of 42 mm and triaxial geogrid were used in this study. Tests were performed at different normal stresses (σn) and shearing rates (Sr) ranging from 35 to 100 kPa and 2.5 to 10.0 mm/min, respectively. To simulate the effects of mud pumping, a predetermined quantity of soil was added that represents a fouling level, void contamination index (VCI), of 40% in the current study. The experimental test results revealed that the shear strength of ballast was highly influenced by the soil fouling. The friction angle of unreinforced ballast is found to decrease from 64.5° to 53.4° when the ballast is fouled with soil. Moreover, the presence of soil fines also decreases the ballast breakage by reducing the inter-particle attrition. However, the inclusion of geogrid was found to enhance the friction angle and reduce the particle breakage of both fresh and fouled ballast. The current study highlights the shear behavior of soil fouled ballast at different rates of shearing and the beneficial effects of inclusion of geogrid in stabilizing the fresh and fouled ballast.

The conventional construction material scarcity and large amount of unutilized industrial wastes causing serious environmental problems and ecological imbalance are the major problems the construction society is facing today. This study aids in the effective utilization of one such waste, pond ash to reduce the environmental problems and to preserve the valuable top soil. The main objective of this study is to reinforce the pond ash with geogrid and study its behaviour (Stabilization by inclusion and confinement). The varying parameters considered are aperture opening, number of layers and the placement depth of geogrid. From the results, the optimum reinforcement design is found out for its utilization as subgrade. An unreinforced and geogrid-reinforced flexible pavement is modelled in finite element axisymmetric modelling and is analysed while subjected to static loading.

Elastic foundation models offer a computationally efficient way for the qualitative analysis of the railway track system. However, the inertial characteristics of the foundation are neglected while modeling the railway track system using those models. This paper investigates the effect of incorporating the mass of the foundation on the behavior of the elastic foundation models under the dynamic train loading. The railway track system is idealized as an infinite Euler–Bernoulli beam resting on a continuous two-layer system with top and bottom layer denoting the ballast and subgrade, respectively. The ballast layer is modeled using inertial elastic shear elements and the subgrade by inertial viscoelastic elements. A time-domain deflection analysis of the proposed model is carried out for various ranges of train speeds. It is found that the incorporation of the inertial characteristics of the substructural system may lead to significant underestimation in the critical velocity values (by up to 85%). Further, the deflection magnitudes and the critical velocity of the system are found to be highly sensitive to the stiffness of the substructure. Higher deflection and lower critical velocity values are observed in the case of soft subgrade as compared to those in the stiff subgrade. Finally, the incorporation of the shear parameter associated with the ballast significantly decreases the deflection magnitudes.

The settlement of high embankments constructed over soft compressible soil deposits is affected by the self-weight of the embankment material. In such situations, lightweight materials are preferred over the conventional earth materials. This paper delineates the geoengineering properties lightweight foamed geopolymer prepared from a mixture of fly ash and ground granulated blast furnace slag with sodium hydroxide as an activator. Aluminum powder, hydrogen peroxide and Triton X 100 are used as foaming agents. UCS tests are conducted to evaluate the mechanical properties after curing periods of 7 and 28 days. XRD and SEM tests are performed to inspect geopolymerization reactions, composition and microstructure of the products. Lowest density of 0.96 g/cc is obtained by using 0.5% H2O2 as foaming agent with unconfined compressive strength of 1.33 MPa indicating that this can be used in sub-base and subgrade of highway embankments, constructed over soft soil deposits.

Steel industry produces substantial amount of steel slag as a by-product generated during manufacturing of pig iron and steel. The steel slag has huge potential to be used in Indian Railways as a ballast material. Steel slag ballast provides high drainage because of its high percentage of void space and exhibits high resistance to degradation. The rapid development of semi-high-speed railway or upgrading the existing one to a higher speed limit and its maintenance under demanding operational conditions have brought new challenges to the Indian Railways. The study on the behaviour of steel slag as railway ballast under cyclic loading is limited and one of the prerequisites for predicting the performance of railway on account of increasing speed and demanding operational condition. This study investigates the cyclic response of steel slag ballast using the parallel gradation modelling technique. The tests were performed on the ballast compacted at two different initial relative density (60 and 90%) and under two different confining pressures (40 and 60 kPa). Resilient modulus, permanent axial strain, shear modulus and damping ratio are determined for two different loading frequency (1 and 3 Hz) and number of load cycles. The impact of various controlling parameters on the degradation behaviour of the ballast is studied.

A numerical study has been carried out to determine the thickness of the top granular layer for a JGT reinforced low volume rural road system based on 3D static finite element analysis. The behaviour of the granular pavement materials has been simulated as an elasto-plastic material. The behaviour of JGT has been considered as a membrane-type material. The determination of the top granular layer thickness is based on the load carrying capacity of the rural road system under the different magnitude of surface deformation. Improvement in the service life of the JGT reinforced rural road has been determined in terms of traffic benefit ratio (TBR). The TBR values are found in the range of 1.22–5.08. In the present work, an attempt also has been taken to study the strength mobilisation of JGT in low volume rural road structure under deformation.

Railways are a form of regular transport for millions of people in India, which makes it an integral part of transportation sector of our country. The modernization of railways is being carried out extensively in order to meet the ever increasing demands of the population. Geosynthetics are being widely used worldwide as a reinforcement material for various applications. Rail tracks are one of the most important and emerging areas where geosynthetics can be used to fulfill the various requirements of reducing track maintenance costs as well as track degradation due to excessive settlements. This paper attempts to investigate the improvement in geocell-reinforced railway tracks using three-dimensional finite element modeling over unreinforced tracks. The sub-ballast heights and modulus of geocell were varied using MIDAS GTS-NX, 2016 which is a commercially available finite element analysis software, to observe the effect of these parameters on the improvement in track-beds using geocell. The results of the FEM analyses indicate that the performance of rail tracks can be improved using geocell as a track reinforcement material.

Railways is a very old form of transportation in India with a vast network of railway track. A large majority of the railway network is old and built according to the codes and demands of the times when they were constructed. There is a need to improve the existing set of railway tracks to run heavier trains for present and future demands. This paper proposes to study the effect of micropile to reinforce the railway subgrades for increased load conditions. Micropiles can be used to enhance the load bearing capacity as well reduce settlements in subgrades. In view of this, the present study explores a finite element method (FEM) model for the simulation of unreinforced and reinforced subgrades with micropiles. Different arrangements of micropiles is considered and optimum configuration for maximum performance is found out. The efficiency of micropiles in improving the railway subgrade is evaluated by comparing the unreinforced and reinforced subgrades. The developed study is helpful in analyzing the mechanism of subgrade improvement using micropile and provides valuable inputs for the design and application of micropiles.

Most of the rural roads in India are over soft subgrade which requires improvement. Structural performance of pavement can be evaluated by Benkelman beam deflection test as well as field CBR test. Improving the soil with coir geotextiles is a good option, as coir geotextiles are natural and indigenous materials with higher durability compared to other natural geotextiles. This paper is focusing on the simulation of a numerical model which could predict the modified CBR value of coir geotextile-reinforced soil and variation in deflection with different coir geotextiles using ABAQUS. Such a model could be effectively used to choose the type of coir geotextile suitable for a particular type of soil. Numerical simulation for predicting the variation in deflection of pavement could be effectively used to evaluate the reduction in pavement deflection with the inclusion of coir geotextiles.

An image analyser (IMAGEJ) has been successfully employed for a comparative study of morphological characteristics of actual and reduced scale ballast particles. In this paper, a detailed procedure has been outlined. The results of analysis of actual and reduced scale ballast particles have been shown graphically using plots between different morphological characteristics (sphericity, aspect ratio, elongation, form factor, flatness) versus roundness and a Zingg diagram (plot between elongation and flatness). Using these graphs, comparative results were tabulated for actual and reduced scale ballast.

A mechanical model has been proposed to study the flexural response of a square plate resting on the viscoelastic foundation. A Burgers model is the series combination of Maxwell and Kelvin model, representing viscoelastic behaviour of soil very efficiently, and therefore, the same has been employed to idealize the foundation soil. The foundation has been modelled as a plate, and its time-dependent behaviour has been studied. Classical Kirchhoff’s theory of thin plates has been employed to undertake the flexural analysis of the plate. Governing differential equations have been derived and solved using the finite difference method with the help of appropriate boundary conditions. The results of a particular case of present work have been compared with those available in the literature in order to validate the proposed model. After validation, first the retardation time of the viscoelastic model, representing degree of rigidity of viscoelastic material, has been determined. Detailed parametric study has then been carried out to study the influence of various input parameters like magnitude of applied load, relative magnitude of elastic and viscous coefficients of Burgers model, tension in elastic membrane and the degree of consolidation, on response of plate in terms of its deflection and the bending moment. This work finds direct application in the analysis of raft foundations and rigid pavements.

Tunnels are proven to be the most important mode of transportation, these days. Due to rapid development of underground space in big cities, it is important to study and analyze huge stresses that are coming to the u/g tunnels due to different loading conditions. Mostly, urban tunnels are highly susceptible to deformation even with the small change in stress distribution of surrounding rock mass. Due to moving traffic and construction and demolition of new and existing structure, u/g structures are always subjected to huge stresses which need to be distributed uniformly for the safety of lining and lives of people. In this paper, finite element method is used to study the behavior of lined and unlined tunnels under the weight of overlying strata or litho-static pressure. In the analysis, vertical stresses on tunnel and lining are being applied in terms of unconfined compressive strength of rocks and geo-material (sm1) for better understanding. Authors have also simulated the effect of weathering on the deformation and stresses of different rock masses. The finite element software ABAQUS is used for simulation work. Mohr–Coulomb plasticity model is used for the different rocks. 3D finite element model is considered of size 0.3 × 0.3 × 0.35 m for 0.05 m overburden. UCS of different weathered basalt and a geo-material prepared in the laboratory applied as a load for both lined and unlined tunnel element. The results conclude that with the increase in the weathering indices of surrounding rock mass, massive deformation was encountered even with very less magnitude of applied vertical and horizontal stress.

The propagation of waves across parallel joints in rock mass involves multiple reflections of waves between joints. Propagation of waves across multiple parallel joints is numerically modeled and presented in this paper using distinct element simulations. The validation of numerical model was performed by comparing wave velocities obtained in laboratory and numerical simulations. For the study on wave propagation across parallel joints, DEM numerical models with varying number of joints were generated. The wave velocities, wave amplitudes and energy flux of waves were monitored. It has been found that as the number of joints in rock mass increases, there is a transition from intermediate wavelength condition to long wavelength condition. The stress waves monitored indicated that there are considerable reflections of waves between joints and waves propagating under intermediate wavelength condition sense the presence of joints. Due to the superposition of waves between joints, the waves may get amplified also.

In this study, an attempt is made to analyze the ballastless track by modeling it in 3D and the solution is obtained using ABAQUS. Design similar to RHEDA® slab track (Germany) has been modeled, which consists of three layers—concrete bearing layer (CBL), hydraulically bonded layer (HBL) and frost protection layer (FPL, for large temperature variation) over subsoil base. In this study, FPL is replaced, and its thickness is distributed in combination of HBL and CBL. Solid deformable parts are used for rail track substructure and superstructure, but wheel–axle part is rigid as it is not to be analyzed for deflections. Mesh convergence study is done by analyzing results for different mesh sizes. Loading is done in static/linear step, and motion is performed in dynamic/implicit step. Indian broad gauge and UIC60 rails are used. Moving load is applied by a wheel–axle assembly sliding motion over rails. Speed variation is achieved by changing time of motion over same distance. The results will improve our understanding of the behavior of ballastless tracks.

This paper provides insights into a series of two-dimensional numerical simulations of the direct shear test using the distinct element method (DEM). The DEM simulations were performed with different inter-particle friction coefficients maintaining the constant normal stress conditions to explore the stress-strain relationships. The microscopic characteristics of the DEM samples and the steady-state properties within the shear band were analysed. From the analysis of results, it can be concluded that the peak stress ratio occurs at a very small global shear strain of approximately 1.5% and it reaches steady state with a relatively larger strain of about 15%. The steady-state and peak friction angles increased with an increase in inter-particle friction coefficient. In addition, all the simulations reported in this paper yielded coordination numbers over 3, indicating structurally stable granular assemblies during any stage.

The mechanical behaviour of granular soils is highly complicated due to the highly heterogeneous behaviour of soils. The discrete nature of these particles calls for the use of plastic theories for the understanding of mechanical behaviour of soils. Constitutive relationships for granular soils can be formulated based on micro-mechanical approach or macro-mechanical approach. The various behaviours like hardening, densification and dilation associated with soils as loading progresses control the overall response of the material. Dilation which is related to the increase in volume of soil mass during shearing is an important parameter which controls the response of a deposit. There are different plasticity models which are in use for predicting the behaviour of granular materials. In this paper, a comparative study of the mechanical behaviour of granular materials when different plasticity models are adopted is presented. Finite element software ANSYS is used for the modelling of the drained and undrained stress strain behaviour of the granular soil mass subjected to static loading.

Expansive soil is unreliable for geotechnical purposes due to excessive compression, dispersion, collapse, low shear strength, low bearing capacity and high swell potential. Multivariate regression modeling has been adopted in this chapter to establish relationships between soil parameters. The aim being better understanding of complex uncertainties and predicting results, for which linear, parabolic and exponent models were designed. Deep excavation was simulated in expansive soil above sand layer using Diaphragm wall, soil anchors and geogrids in PLAXIS 2D, and numerical analysis was performed to predict the soil behavior during excavation with the aim of better visualization of discretized elements, calculation of stress, deformation in soil and more stable computing process. The primary objective of this chapter is to establish relationships between soil parameters by mathematical modeling and analyze practical situation by simulating staged deep excavation in expansive soil through numerical modeling.

Numerical analysis was carried out to investigate the response and failure mechanism of monopod bucket foundation embedded in sand and subjected to eccentric lateral loading. With increasing loading height, the ultimate lateral capacity of the bucket foundation is noted to decrease, whereas the overturning moment resistance and lid centre angular rotation at failure are observed to increase. Under pure lateral load, the bucket foundation fails by dominant lateral translation, and the soil plug yields plastically resembling a shape similar to an inverted scoop above the base of the soil plug. With increasing loading height, rotational translation progressively dominates the failure of the bucket foundation, and the nature of plastic deformation gradually changes to an external upright scoop shape below the base of the soil plug. Based on the results, expressions are proposed to predict the ultimate and allowable lateral capacities of the monopod bucket foundation.

This paper aims to investigate the bearing capacity factors (Nc, Nq, and Nγ) of a strip footing, resting on the surface of a cohesion–frictional soil medium, using the displacement-based finite element method. The analysis is carried out by considering both associated and non-associated flow rules. Both smooth and rough footings are considered for the analysis, and the bearing capacity factors are estimated for a wide range of friction angle and dilation angle of the soil. Results reveal that as the dilation angle of the soil increases, bearing capacity factors also increase and this increasing trend intensifies as soil friction angle increases. Nγ values are highly dependent on both the roughness and width of the footing. It is observed that Nγ values are higher for the rough footing surface than the smooth one, and the values decrease as the footing width increases. A comparative study between the present analysis and the previous investigations is carried out, and it is found that the present results are in a good agreement with the results obtained by the previous researchers. Finally, the fuzzy reliability analysis is performed to identify the effect of the coefficient of variation of soil friction angle and the spatial correlation length on the probability of failure of footing considering spatial variability of the soil parameters.

Coefficient of compression or compression index is a vital parameter to calculate the settlement of soil. A conventional Oedometer test, which is cumbersome and time taking, is performed to calculate this parameter. In this paper, artificial neural network (ANN) has been adopted to predict the coefficient of compression from more simply determined basic properties of soil. In order to develop the ANN model, 266 consolidation test data for soils sampled at 72 boreholes at 18 construction sites in Allahabad, India, were collected from reputed laboratories. Two hundred and thirty-six of these data were used to train the prediction model and the remaining 30 were used to examine the developed ANN models. The ANN model consisted of SPT-N value, liquid limit, plasticity index, specific gravity and dry unit weight as input parameters followed by the target as coefficient of compression. The correlation of the predicted values with the actual values was determined, and it was found that mean absolute error (MAE) varies from 3.53 to 5.45%, root mean square error (RMSE) ranges from 4.34 to 7.42% and coefficient of correlation (R2) value lies between 0.8615 and 0.9706. Hence, artificial neural network can be used with a high degree of accuracy in the prediction of coefficient of compression for new cases.

The present study pertains to the probabilistic analysis of conically shaped excavation in purely cohesive soil with the incorporation of the randomness of undrained shear strength of cohesive soil (Cu). Axisymmetric lower bound finite elements limit analysis technique is employed to compute the stability number (Ns = γH/Cu) of conical excavation which is a function of slope angle (β) and ratio of excavation height to bottom radius of the excavation (H/b). Failure probability (pF) of the conical excavation is computed by using random field theory in conjugation with Monte Carlo simulation. Probabilistic design charts are presented for various combinations of coefficient of variation of Cu (CoVcu), correlation distance (δ), β and H/b. Design charts indicate that the value of Ns increases with the increment in the value of H/b but reduces with the increase in slope inclination. The magnitude of pF is found to be increasing with an increase in CoVcu value for a particular value of δ.

It is well known that the soil exhibits nonlinear behavior when stressed under different condition. Therefore, it is a topic of interest for many researchers to study the failure mechanism of the soil considering its plastic nature. This led to the development of different constitutive modeling techniques. Analysis of geotechnical problems using finite element method (FEM) combined with constitutive laws ensures precise prediction of the behavior of complex problems. Shear strength parameters of soil also depend on amount of strain applied to the soil mass. This paper presents the effects of variation of plastic strain on shear strength parameters of soil. The nonlinear behavior of soil with two types of laboratory tests attributing to variation in plastic strain is simulated numerically using a FORTRAN subroutine linked with ABAQUS. The results are compared which shows how important it is to consider the variation of plastic strain when the numerical analysis is done.

Offshore pipelines undergo deformations when they are subjected to the hydrodynamic loads due to the combined action of waves and currents. The stability of these pipelines in terms of vertical as well as lateral direction is of important concern. Most of the studies in the literature focused on the pipeline laid on the clayey soil considering the pipe as a rigid material. This study presents the behaviour of the pipeline laid on the sandy soils considering the pipe as a rigid material. Finite element analysis using PLAXIS 3D has been carried when the pipe is subjected to vertical, horizontal, and combined vertical–horizontal loading. The length of the pipe is considered to be sufficiently long and taken to be 40 m. The seabed is modelled as a Mohr–Coulomb material with uniform strength throughout the depth. The V-H yield surfaces are presented for different pipe embedment and for different relative densities of the soil. The depth of embedment (w/D) considered is 0.5 and 1. The yield envelopes developed are useful in assessing the ultimate resistance of the pipelines.

The use of continuous geosynthetic inclusions is involved in traditional soil reinforcing techniques such as geotextiles or geogrids, which are strong in tensile resistance. They protect the environment and promote a stronger planet by conserving energy and the earth’s resources through the production of durable and sustainable structures. In the present investigation, a numerical analysis is performed to understand the behavior of a square footing resting on geogrid reinforced soil. The numerical simulations were carried out using a three-dimensional FEM software, PLAXIS 3D. The numerical model was systematically validated with the results obtained from experimental studies. The effect of various factors such as embedment depth of first layer, spacing between consecutive layers and the multi-layers of the reinforcing elements are studied. It is observed that, four numbers of geogrid elements give the maximum bearing capacity ratio of 3.51 for an optimum depth of first layer and the spacing of 0.25B.

When a portion of the soil mass yields, redistribution of stresses takes place between the yielding mass and the adjoining non-yielding soil. This phenomenon is known as soil arching. Several trapdoor experiments were performed with different improvements and extensions over the past few decades to study soil arching. Numerical modelling of a trapdoor mechanism is performed in this study, and the suitability of the Mohr–Coulomb model and Hardening Soil model have been studied and compared. The Mohr–Coulomb model is generally being used for the numerical analysis considering its simplicity. An advanced soil model can be used to create more realistic soil response. The Hardening Soil model is an effective and better model to simulate the real soil behaviour in terms of stress dependency, nonlinearity and inelasticity. The present study highlights salient advantages of Hardening Soil model over Mohr–Coulomb model for the numerical modelling of trapdoor mechanism.

Shear modulus (G) of soil is an important parameter in considering the effect of soil–structure interaction while analyzing the response of structure against earthquake motions. Cyclic tri-axial test gives best laboratory results for shear modulus. However, this test is expensive and has to be conducted for many days continuously. In general, shear modulus is related to mass density of soil and shear wave velocity of the soil strata. In the present study, adaptive neuro-fuzzy inference system (ANFIS) is developed for the prediction of shear modulus of the soil. For this system, input parameters are Dry Density, Moisture Content and SPT-N value of soil. ANFIS model is used for automated rule generation and parameter optimization. For this research, vast data of shear modulus from different site locations were used and trained for three models. The results have shown that the ANFIS model is the best choice for the prediction of the shear modulus and represent the relationship between soil properties and shear modulus.

Geometrically, systematic arrangements of grain particles (idealized as spheres of varying radii) and the relationships with particular petrophysical properties of sedimentary rocks provide a basis for understanding the principles behind the concept of porosity and permeability, which is quite useful for studies related to petroleum exploration and extraction. Porosity, being the main storage parameter, is mainly controlled by primary syn-depositional sedimentary parameters such as the grain size, grain shape, sorting, packing, and orientation. The present paper deals with the geometry of various ideal and near-ideal assemblage of discrete grain particles (spheres) for a sandstone rock core sample obtained from Disang, Mizoram region which is known for undertaking hydrocarbon activities. Several cases of packing (cubic, orthorhombic, and rhombohedral) are studied including the theoretical model along with the obtained model from digitally analyzed image through FESEM with the help of ImageJ software. Thus, it is concluded that such a method potentially provides quantitative data on porosity at the micro-meter to millimeter scale by generating realistic numerical data on porosity so as to characterize the nature of pore systems at this minute level, thereby providing useful information suitable for modeling flow through porous media such as porous reservoir rocks. Comparative tabulation of these different models discloses the wide variation in porosity values obtained by the difference in packing of grain sizes.

Dissipation of pore water pressure during vacuum consolidation is a complex phenomenon and is not uniform about the soil stratum. It is rapid near the drainage boundaries and becomes gradual with the distance away from the drainage boundary. However, it is observed from coupled deformation studies that pore water pressure undergoes an initial rise between the two drainage boundaries before they finally decrease. This excess rise in pore water pressure due to the application of external load is called as Mandel–Cryer effect. Because of possible experimental errors and ramp nature of loading in the field, this effect is difficult to be captured in situ. Besides, the dependency of this effect on Poisson’s ratio (v) of soil mass has been cited in the literature. To have a better understanding of this behaviour under vacuum pressure, a 2D numerical study has been conducted and the influence of Poisson’s ratio on the change in pore water pressure and horizontal displacements under vacuum pressure is discussed in this paper.

For accurate prediction of mechanical behaviour of cemented clay, a realistic description of its constitutive relation is important. In this study, within the framework of critical state soil mechanics, the bounding surface concept is employed to model the behaviour of cement stabilized soil. The plastic modulus proposed is load path-dependent where radial mapping rule is used for the imaginary points on the bounding surface. This bounding surface model, which includes tensile strength due to cementation effect, is extended to general stress space for implementing it in ABAQUS. The parameters for the model can be easily obtained from conventional triaxial drained and undrained tests and 1D consolidation test. With different boundary conditions, simulations are carried out for drained and undrained triaxial tests for a wide variety clay with different cement contents. In simulation, key attention is given to stress–strain behaviour and ultimate strength of cement stabilized clay.

Pile foundations are frequently subjected to a significant cyclic lateral load from wave and wind action, in case of offshore structure. In the present study, the behaviour of pile subjected to two-way cyclic loading is investigated through the numerical analysis. The numerical analysis is the simulation of laterally loaded pile under two-way cyclic loading in soft clay. The cyclic loading consists of five continuous episodes of cycling with the amplitude of cyclic loading increases from 0.25 to 0.75 times of the ultimate capacity of single pile. The analysis is carried out using two-dimensional finite element software PLAXIS. The effect of two-way cyclic loading on the load–displacement and dynamic time is studied in this paper. From the result, it is observed that the increases in loading and dynamic time there is an increase in displacement.

Ground-penetrating radar (GPR) is an instrument that works by the principle of electromagnetic wave propagation and is of great use for in situ ground analysis. Its potential uses in the field of geotechnical engineering are not fully explored with sufficient vigour though, due to economic reasons and the highly heterogeneous nature of soil. Taking this into account, if the instrument can be calibrated specifically for geotechnical purposes, it can reduce the number of experimental analyses that need to be carried on soil and can also reduce the necessity of undisturbed samples of soil to a good extent. The present study discusses the calibration of GPR, through clay content of soil with some of its properties like particle density, bulk density, porosity, void ratio with the dielectric permittivity and peak wave frequency which are obtained from GPR data. Based on the database available in literature, the detection of clay content in three different grades of soil A1, A2 and A3, classified as per American Association of State Highway and Transportation Officials (AASHTO), is done using some recently developed AI techniques, multigene genetic programming (MGGP) and feature selection using NSGA-II, multivariate adaptive regression splines (MARS), Gaussian process regression (GPR), support vector machine (SVM). The predictive capabilities of these methods are discussed through coefficient of correlation (R2), root mean square error (RMSE), average absolute error (AAE) and overfitting ratio. Based on above statistical parameters, it was observed that NSGA-II algorithm trained using ANN is showing better capability for predicting the clay content, with R2 value of 0.99 for both test and train data the least RMSE of 0.58 and 0.65 for test and train data, respectively. Though the number of data points is limited, the AI methods used could predict the values with very good accuracy.

By using the lower bound finite elements limit analysis, this paper presents a methodology to evaluate the bearing capacity of piles in cohesive soils. The non-homogeneous nature of soil has been assumed for which the cohesion increases linearly with depth. An axisymmetric formulation, comprising of a planar domain with a mesh of three noded triangular elements has been adopted. Here, Mohr–Coulomb (MC) yield criterion has been employed. The yield criterion is expressed in terms of three quadratic constraints so that the problem can be solved using second-order cone programming (SOCP). Bearing capacity factors have been generated as a function of (i) height to radius ratio of the pile, (ii) rate of increase of cohesion and (ii) roughness of base and shaft of pile. The results computed from the analysis have been compared thoroughly with that reported in literatures.

Finite element-based upper bound and lower bound limit analysis are found to be an excellent tool for solving various stability structural problems with less computational cost. The accuracy and efficiency of the obtained solution is highly dependent on the intensity of elements in the high stress or stain gradient region. Therefore, an adaptive meshing procedure is required to reduce the gap between upper and lower bound solutions. The adaptive meshing procedure presented in this paper is based on two basic concepts (a) a posterior error indicator and (b) an unstructured mesh generator. The posterior error estimator is based on intensity of maximum shear strain rate ( $$\gamma_{ \max }$$ γ max ) has been used. Open-source software TRIANGLE and TETGEN have been used to generate unstructured meshes for 2D and 3D problems, respectively. A plane strain and a 3D foundation problem have been analyzed and steps involve in calculation have been clearly mentioned in the paper. The present analysis method is found to be efficient and accurate.

The soil liquefaction is a major earthquake disaster which causes tremendous damages to all infrastructure facilities. The examples during past earthquakes have shown the evidence of liquefaction-induced ground failures in fine-grained soils. Until recently, liquefaction-related studies concentrated on clean sands believing that only sands are susceptible to liquefaction. However, the earthquakes like 1976 Tangshan earthquake, the 1989 Loma Prieta earthquake, the 1999 Kocaeli earthquake, the 2010 Chile earthquake, and the 2011 Christchurch earthquake, etc., showed that sand with fines could also liquefy. The present study deals with the numerical simulations on cycling loading effects on the undrained response of silty sand. The material parameters for the numerical model are found after conducting basic experimental tests. The response of silt sand under the undrained condition of cyclic triaxial loading is analyzed using the hypoplastic constitutive model. The influence of soil parameters, i.e., void ratio/relative density and consolidation pressure level on undrained response of soil is examined from model simulations.

The preliminary geotechnical investigations for large infrastructure sites are performed on a coarse grid. However, in most cases, the requirements of the estimation of foundation parameters at the building location would not be satisfied with such coarse grid data. This calls for suitable technique to estimate data at fine grid resolution from the coarse grid data available from the preliminary soil investigation. This paper deals with the estimation of SPT values or N-values or SPT-N-values at desired location from an available coarse grid data using various spatial interpolation techniques. Geo-statistical methods selected for the present study are inverse distance weighting (IDW) method, trend surface analysis (TSA) and k-nearest neighbour (KNN) mean method. IDW method estimated the SPT values at 1.5 m depth with good accuracy followed by KNN averaging method, whereas TSA was pretty poor. The predicted SPT-N-values can be used to estimate the subsurface information, allowable bearing pressure of soils and elastic modulus of soils. This would be extremely useful for executing the activities of design and additional geotechnical investigations on parallel mode and thereby saving on the overall project time.

In this world, different types of soils are present. These soils are consisting of different types of soil particles. The engineering properties of soil are defined on the basis of particles size and consistency limits. Soil was classified into different divisions and subdivisions by different organizations. International classification, highway research board, MIT, AASHTO and many other classifications are available, but these classifications are having limitations in describing or defining the soil and soil mass. Due to this reason, a new classification of soil is proposed with the name modified textural soil classification. The modified textural classification is developed using the concept of two existing soil classifications, namely the international classification system of soil and textural classification system of soil. The original textural classification systems of soil used triangle for soil classification based on particle size distribution considering sand, silt and clay as the type of particles. Modified textural soil classification has introduced two overlapping triangles, coarse and fine triangle based on particle size considering gravel, sand, majla, silt, clay and ultra-clay as the type of particles. In this way, another triangle is formed, namely middle triangle which is more helpful in classifying soil. In modified textural classification, the two triangles are overlapped at the 50%.

Coefficient of secondary compression is one of the important consolidation properties of fine-grained soils exhibiting high secondary compression. Generally, soils containing significant amount of organic matter exhibit high secondary compression. It is generally determined by performing laboratory one-dimensional incremental loading (IL) consolidation test, in which each increment is allowed for 24 h or more. Typically, conventional one-dimensional IL consolidation test takes about 10–14 days to complete. Therefore, end-of-primary consolidation (EOP) test and rapid one-dimensional consolidation tests were developed in the literature to reduce the duration of conventional IL tests. The limitation of these methods is that coefficient of secondary compression cannot be determined as the specimen is not allowed to reach the secondary compression phase. This paper describes a method of determining coefficient of secondary compression from accelerated incremental load consolidation testing procedure using $$\sqrt{t}$$ t method. In the proposed method, one of the pressure increments is left for sufficiently long time to obtain the linear secondary compression phase in the log t plots. The suggested procedure is validated by comparing the results obtained from the conventional IL consolidation test on four soil samples with varying range of secondary compressibility and plasticity characteristics.