Advances in Computer Methods and Geomechanics

Nanoclay is a fine-grained crystalline material, which contains a mineral of alumina and silica with high aspect ratio and at least one dimension of a particle in the nanometer (1 nm = 10−9 m) range. Nanoclays have various applications in many fields, including problematic soil treatment, pharmacy, medicine, catalysis, cosmetics, food packaging, and textile industry. The raw cost of Nanoclay is high due to its costly manufacturing process that involves heavy chemicals and machinery. Therefore, the aim of the current research is to extract Nanoclay from the montmorillonite-rich commercially available Bentonite soil using a cost-effective method. The process involves the exfoliation of the nanosized lamina from the stacked 2:1 tetrahedral–octahedral laminae of montmorillonite minerals with the help of surfactant. Three different types of surfactants (cationic, nonionic, and anionic) were chosen in the current study to evaluate their effect on the exfoliation process of highly expansive Bentonite soil. A series of chemical processes including solution preparation, sonication, centrifugation, and drying were performed using selected proportion of surfactant and Bentonite soil mixture. Physical and chemical properties of the end product were investigated by performing X-ray diffraction (XRD) technique and scanning electron microscope (SEM) image analysis. Nanoclay of the particle size range of 10–15 nm is successfully exfoliated from montmorillonite sheet structure by the chemical interaction between cationic surfactant and Bentonite soil. Nonionic surfactant was observed to be just intercalated between the sheets of montmorillonite mineral with additional growth of small needle-like structures. Anionic surfactant has no prominent effect on Bentonite soil.

Bentonites are increasingly used for various geoenvironmental applications (e.g. hydraulic barriers and waste containment) owing to its low hydraulic conductivity and high water retention capacity. Investigating the aforementioned problems necessitates the knowledge of the water retention curve (WRC) of bentonite, which maps the variation of the degree of saturation (S) with suction ($$\psi$$). It is now well established that there are various uncertainties associated with WRC. In this study, a database exclusively for the WRC of bentonite is presented. The uncertainties in the WRC parameters of the database are quantified using the copula approach and thereafter confidence intervals are created. Finally, as an application example, the confidence intervals are used to calculate uncertainty bounds in an unsaturated transient seepage problem.

The study is focused on analyzing and designing backfill retaining systems for a berth with respect to permissible deflection and overall consumption of concrete and steel. It includes analyzing and designing of RCC piled jetty with three types of earth retaining systems, namely slope fill (Type 1), diaphragm wall separate from the jetty (Type 2), cantilever wall attached to the jetty (Type 3), and with two different vessels of 5000 DWT (V1) and 3000 DWT (V2) under different site conditions. The different conditions consist of different water depth, different soil conditions (loose, medium, and hard), different seismic zone (II, III, IV, and V), and earth pressure for different backfill soil parameters and slope fill. The Axial force, Moments (My and Mz), and Concrete and Steel consumption are compared with respect to different water depths for all the zones and type of soils. The three systems are then compared against one another to find the most economical section. Also, the material consumption factor is found. It was observed that the slope fill (Type 1) and 9 m system are most suitable in terms of economy as a backfill retaining system for onshore RCC pile berth. With the change in soil from hard to loose, the pile diameter increases. Also as the width of jetty increases, in case of Type 1 system, the structure becomes less economical due to increased forces.

The effect of pore fluid concentration on the hydraulic conductivity of barrier material is one of the key factors which are considered in the long-term performance of a geological repository. The current study presents the effect of various NaCl concentrations on Atterberg limits and hydraulic properties of two bentonites and one kaolin clay. The results indicated that the liquid limit, shrinkage limit, and consolidation characteristics of bentonites such as compression index (CC) and the time required for 90% of consolidation (t90) were decreased significantly with an increase in salt concentrations. Similarly, the hydraulic conductivity and coefficient of consolidation (Cv) increased drastically with increase in salt concentrations; however, the significant impact was found for the high smectite bentonite. The experimental results showed that the hydraulic conductivity of the clays mainly depends on the particle arrangement rather than percentage of clay fraction and consolidation stress. For kaolin soil, both the liquid limit and shrinkage limit were found to be slightly increased up to 0.5 M NaCl, however, the effect was found to be decreased at further increase in concentrations, whereas hydraulic conductivity was found to be increased with increase in NaCl concentration. Further, the effect of molding water content on the consolidation characteristics of the clays was also investigated. The parameter compression ratio was used to evaluate the impact of initial moisture content on the compression index of the soil specimens. The hydraulic conductivity of the clays was noted to be increased at higher pore fluid concentration, due to the diminishing of the diffused double-layer thickness of clay minerals.

The bearing capacity of footings has been extensively studied, both theoretically and experimentally over the past decades. In all the type of footings except shell foundations, the shape of the cross section adopted is rectangular and the base has been considered as a plane surface. The pattern of soil movement beneath the footing during loading is a significant factor contributing to the load–settlement behaviour. By altering the shape of the cross section of the footing, it would be possible to provide better confinement of underlying soil thereby improving the load–settlement behaviour. This paper investigates the influence of the shape of the cross section of the footing on its behaviour. The different shapes of the cross section of footing adopted for the study are sloped cross section, curved cross section and rectangular cross section with vertical flanges. A series of non-linear finite element analyses are carried out with the FE software PLAXIS 2D and the results are validated by carrying out laboratory scale load tests and comparing the results. It is observed from the results that the load–settlement behaviour of the footings can be significantly improved by altering the shape of the cross section. The improvement is significant when the shape of the cross section is Curved or Rectangular with flanges. The optimum length of flanges is observed to be 20% of the width of the footing.

Kuttanad region is the largest agricultural area in the state of Kerala. Kuttanad clay is an important soil group, well-known for its low shear strength and high compressibility. The typical Kuttanad soil consists primarily of silt and clay fractions. The natural water content of the soil here is very high and close to the liquid limit. Since Kuttanad is the rice bowl of Kerala, any technique adopted in this region should be eco-friendly and should never cause any harm to the soil and water. This paper discusses the stabilization of Kuttanad clay using biopolymers. Two types of biopolymers were (Xanthan gum and Guar gum) used in this study due to their availability with reasonable prices and their stable behavior. A laboratory study was conducted on Kuttanad clay treated with Xanthan gum and Guar gum, and variation in soil properties was analyzed. The biopolymer was added in different concentrations so as to identify an optimum dosage. From various tests, it was observed that with the addition of Xanthan gum the optimum moisture content has decreased by about 7.4% and the Unconfined Compressive Strength has increased by 51.5% and with the addition of Guar gum, the optimum moisture content has decreased by 17.6% and the Unconfined Compressive Strength has increased by 59.5%.

In the area of geotechnical earthquake engineering, liquefaction is most imperative, difficult, and notorious matter. It is a major contributor to urban risk. Liquefaction is the process whereby soil loses its strength and stiffness under the application of stress, where stresses get developed due to ground vibrations during earthquakes. The subsoil strata of Ahmedabad region consist of silty sand, which is one of the responsible factors for the liquefaction susceptibility. In the present study, Idriss and Boulanger [1] method is used which is based on SPT-N value. Before attempting the rigorous investigation of the liquefaction potential for Ahmedabad region, first qualitative assessment of liquefiable soils was carried out based on the geotechnical characteristics such as SPT-N value, depth of water table, grain size analysis, liquid limit, plasticity index, etc. The qualitative assessment of liquefaction potential was done by SPT method using subsurface data and PGA values were generated The different hazard maps were generated using SPT values of different depths for the quantitative assessment of liquefaction potential. Analysis reveals that Madhupura, Shyamal, and Vatva area are likely to be liquefied. If groundwater table is assumed to be at ground level in Ahmedabad region, the results show that the severity of liquefaction would be moderate to high due to the thick shallow liquefied deposits.

Biological phenomena standout as a key towards green method for improving the properties of engineering construction material. The present study investigates the effect of Microbial Induced Calcite Precipitation (MICP) and Extracellular Polymeric Substance (EPS) produced by Bacillus cereus (B. cereus) SG4 on “shrinkage-swelling” behavior of expansive soil. The soil used for the study was commercially available Bentonite cohesive soil. The critical soil parameters such as Liquid Limit (LL), Plastic Limit (PL), and Differential Free Swell Index (DFSI) were found to be very high (LL = 608%, PL = 50%, and DFSI = 661%) due to the presence of Montmorillonite mineral. The results showed that treatment of Bentonite expansive soil with bio-calcite and EPS containing B. cereus SG4 culture media worked effectively. Bentonite soil was treated with bacteria along with culture medium for 5 and 10 days. It was observed that there was no significant reduction in geotechnical properties after 10th day of treatment. Maximum effect was observed at the end of 5th day exhibiting the efficiency and strong capability of proposed soil treatment method. After 5th day, LL, PL, and DFSI values were observed to be decreased; 177%, 39%, and 371% for EPS, respectively. The similar response was observed for Bio-calcite technique, which exhibited a significant reduction in LL, PL, and DFSI values (158%, 39%, and 271%), respectively. Both the treatment techniques worked successfully in improving the shrinkage-swelling response of Bentonite soil, but bio-calcite treatment was observed to be more effective than EPS treatment to control the shrinkage-swelling response.

Simple procedures are available to capture the characteristic response of loose sand under cyclic loading in free field conditions. However, the applicability of these procedures to evaluate the performance of the geotechnical structures overlying the saturated granular soil remains as a concern since the responses exhibited by the soil are very complex in these cases. One such case involving the strip foundation on top of liquefiable sand is numerically studied. The constitutive behavior of the sand is modeled using PM4Sand. In addition to the basic case, soil densification which has been a traditional remediation measure against liquefaction of saturated loose sand deposits is considered to mitigate the deformations of the strip footing. The depth of densified column below the footing is varied in order to assess its influence on the performance of the footing during seismic shaking. The settlement and excess pore water pressure corresponding to the five different cases of numerical model including an untreated model and four other models with different vertical extent are presented and its implications on the response of the footing are discussed.

The objective of this article is to present, qualitatively, the impact of strain rate on the strength behaviour of dry cohesionless sands. The strength behaviour was studied from the aspect of friction angle and dilation angle. A significant number of tests were performed in the direct shear test apparatus for different combinations of normal stresses and shearing strain rates. Shearing strain seems to have a noticeable impact on both the measured strength parameters. For a constant normal load, it is observed that as the shearing rate increases, shear strength increases up to a certain level and then it decreases. The rate of this decrement with respect to the strain level is also a function of the applied normal load. Insightful observations were made for the dilation angle as well. These laboratory observations and interpretations would be further helpful in designing the geotechnical structures in practice.

The paper investigates the compaction and unconfined compressive strength (UCS) of bentonite-rock quarry dust (B-Q) mixtures for assessing the suitability of a cost-effective material for landfill liner. There is a criterion that the UCS of greater than 200 kPa is desirable for liner material for landfill applications to account for the load placed above (Younus and Sreedeep in J Test Eval 40:357–362). The bentonite–sand mixtures are commonly used as a liner material in landfills. As the sand is a scarce material, it is important to find suitable substitutes against the sand. The rock quarry dust is a waste material which can substitute sand to improve the geotechnical properties of soil. In this study, four different B-Q mixtures have been used to determine their compaction and UCS characteristics. The rock quarry dust content varied from 60 to 90%. The UCS values of the mixtures were obtained using the unconfined compression testing machine under two different deformation rates. The results indicated that the maximum dry density (MDD) and UCS value increased significantly when the rock quarry dust content was increased from 60 to 70%. But, the MDD value remained almost constant and the UCS value decreased significantly when the rock quarry dust content was increased from 70 to 90%. The results further revealed that the deformation rate considered has minimum influence on the UCS of the mixtures. Based on the MDD and UCS values obtained, the study recommends an optimum rock quarry dust content of 70% to be added with bentonite to create a cost-effective liner material, especially for landfill applications.

Geopolymer technology is gaining a lot of interests in research and development because they act as a ‘versatile admixture’ for different purposes. The focus of the present work was: (1) To investigate the suitability of Bentonite soil for the synthesis of Geopolymer (2) To investigate the effect of Bentonite soil-based Geopolymer for potential improvement in swelling–shrinkage behaviour of expansive soil. The source material for Geopolymer synthesis was commercially available Bentonite cohesive soil. The presence of montmorillonite mineral causes high water absorption response and swelling–shrinkage behaviour, which makes it extremely difficult to use for civil engineering construction purposes. The critical soil parameters of Bentonite soil such as Liquid Limit (LL), Plastic Limit (PL), Differential Free Swell Index (DFSI), Plasticity index (PI) and Flow index (If) were found to be very high (LL = 609%, PL = 51%, DFSI = 662%, PI = 558% and If = 0.55) due to the presence of Montmorillonite mineral. Remarkable improvement in the properties was observed after treating Bentonite soil with 4% of synthesized Geopolymer. The sample was prepared on weight basis and were cured for a period of seven days, after the end of curing period the test was conducted. A drastic reduction in the studied parameter was observed, after the seventh day, the LL, PL, DFSI, PI and If values were observed to be decreased; 509%, 40%, 329%, 469% and 0.28, respectively. Thus, the study revealed that Geopolymer can be effectively used for treating expansive soil.

The cyclic shearing response of granular materials is highly influenced by various parameters such as void ratio (e), confining stress (p′), initial static shear stress (qs), cyclic deviatoric stress (qcyc), stress reversal and non-stress reversal conditions. Traditionally, most liquefaction studies evaluated the influence of e, p′, qcyc and reversals on isotropically consolidated specimens where qs is zero. However, a soil element in a level ground is normally or K0 consolidated and hence subjected to a qs. Extensive studies have suggested that qs may dramatically alter the pore water pressure generation (Δu), deviatoric strain (εd) and soil fabric for same e, p′ and qcyc. In order to evaluate the effect of qs alone, it is required to produce replicated specimens through different consolidation paths to achieve different qs. Since, it is hard to replicate specimens and assess soil fabric in laboratory, this study used an alternative approach, discrete element method (DEM), which has reproducibility and trace micromechanical parameters such as coordination number, CN and fabric. It is found that Δu, CN and fabric were significantly affected by consolidation path and corresponding qs conditions. This study provides a good understanding on the effect of qs on cyclic response of soils.

Tunnelling in mountainous terrain using sequential excavation activities like New Austrian Tunnelling Methods (NATM) methods has been on the rise due to increased haulage and transportation demands. These structures are normally constructed in stages, where exposed tunnel face will be supported by some additional measures. However, in tectonically active places, like in the Himalayas, it is highly possible to have failure at the tunnel face due to seismic activities. In this study, such an excavation is considered using three-dimensional finite element methods. Face stability of such a system is ensured using certain face deformation criteria. Further efficacy of such measures during seismic activities is monitored using pseudo-static methods. For such an analysis, Peak Ground Acceleration (PGA) of a typical earthquake of Himalayan origin is considered. It was observed that proposed face support systems should be enhanced for such excavations in seismically active zones.

Earth retaining walls are the alleviating structures used to avert downward slope movement of earth masses and provide sustenance for vertical or near vertical grade changes. For designing these structures, it is necessary to regulate the earth pressure exerted by the soil behind the wall. But in seismic prone areas, retaining structures experience maximum devastation as dynamic loads are repetitive in nature. Mononobe–Okabe method based on pseudo-static approach gives an approximate value for the linear distribution of seismic earth pressure by considering the parameters like wall friction angle, soil friction angle, horizontal, and vertical seismic coefficients. The present work includes the determination of dynamic earth pressure coefficients by using Particle Swarm Optimization (PSO) technique. The effects of wide range of parameters like shear wave velocity, primary wave velocity, time effects, and phase difference on earth pressure coefficients have been studied. A comparison has been made between the pseudo-static and pseudo-dynamic earth pressure coefficients to highlight the realistic and nonlinearity nature of seismic active earth pressures. It is found that the horizontal and vertical seismic accelerations are more significant for the computation of dynamic earth pressure, which is highly sensitive to soil friction angle and less sensitive to wall friction angle. The results obtained in the proposed method are also compared with reported results, which show a good agreement.

Shallow foundations are commonly used for supporting structures unless soil, loading and serviceability requirements necessitate deep foundations. Shallow foundations may be designed as rigid or flexible foundations depending on loading conditions as well as relative stiffness of foundation and supporting soil subgrade. For design of flexible foundations, soil is modelled as per Winkler approach or as a continuum. For analysis of most foundations, Winkler approach is found acceptable, wherein modulus of subgrade reaction is evaluated and applied as soil springs. The different factors which affect design of foundation include superstructure geometry and stiffness; type, magnitude and location of loading; rigidity of foundation and modulus of subgrade reaction. The current study attempts to understand the influence of rigidity of foundation and modulus of subgrade reaction on behaviour of raft foundation. A multistoreyed structure is analysed in Staad Pro V8i software for different combinations of foundation rigidity and modulus of subgrade reaction; and parameters such as base pressure, settlement, shear stress and bending moment have been compared. It is concluded from the study that modulus of subgrade reaction has higher influence on variation in foundation base pressure as compared to rigidity of foundation. It is also noted that impact of variation in modulus of subgrade reaction on structural design of foundation is negligible. However, the rigidity of foundation influences the shear stress and bending moment in foundation. It is opined that such studies would help in developing decision matrix to account for various parameters in optimization of foundation design.

The silty soils are more susceptible to liquefaction, even under static loading, than the coarse sands. Pore pressure developed during dynamic events may not dissipate easily due to the presence of more number of small voids. Hence, the rate of pore pressure build-up under static/dynamic loading conditions is much faster in silty sands, which lead to a reduction in the soil strength. This phenomenon may be assessed in terms of either contraction or dilation behaviour under triaxial loading. Therefore, it is necessary to analyse the undrained response of silty sands under triaxial loading so that the damages occurring during future dynamic events may be predicted. The present study involves both the experimental and numerical simulations on various silty sands, which contain 0, 10, 20, 30 and 40% silt fines. Initially, experimental static triaxial testing was performed to determine the undrained response of silty sands moulded to cylindrical specimens at medium relative density. The saturated samples are isotropically consolidated at 100 kPa pressure before shearing. Further, numerical simulations were performed on silty sands by inputting the material parameters into the hypoplastic model. This model requires eight material constants as input including critical friction angle, hardness coefficients, limited void ratios, peak state and stiffness coefficients. These constants were determined for each silty sand combination after conducting basic laboratory tests according to the formulations build in the hypoplastic model program. The experimental trends were compared with numerical model simulations under triaxial testing. The effect of the initial state of soil and the amount of silt fines on the undrained response of fine sands is discussed in detail. The liquefaction susceptibility of silty sand is described based on steady state line concept. The results indicate that the silt sands behave as highly contractive, i.e. more liquefiable when compared with sands.

The objective of the study is to understand the seismicity of the Western coast and its adjoining regions whose seismic potential has not been evaluated so far. The study area encompasses a major portion of Karnataka and Northern part of Kerala and Goa. The approach incorporated in the study is probabilistic in nature and attempts to capture the uncertainty involved in various phases of hazard estimation. The seismic sources in the study region are mostly diffused in nature and are modeled as areal sources with uniform seismicity within a source zone. Regionally, adaptable ground motion prediction equation constitutes the ground motion modeling. The epistemic uncertainty involved in the selection of ground motion models is addressed by adopting a logic tree approach. The seismic source model and the ground motion model are combined together to produce hazard curves for the study region. Most of the ground motion prediction equations are developed for hard rock conditions (Vs > 800 ms−1). However, most of the built environment rests on the soil and there is a necessity to estimate the hazard values at the surface level. Based on the site topography, it was observed that majority of the study area belongs to NEHRP site class C and D. The hazard values were estimated for the boundary site condition CD (310 < VS (30) < 520 ms−1) using a nonlinear site amplification model. Seismic hazard maps produced from this study are believed to be of immense use for building planners and designers.

Reflective cracking is the major issue in hot mix asphalt overlays. Many methods are developed to retard these reflective cracking; among them, the most suitable method is the usage of interlayers. Geosynthetics has good tensile strength and can act as a stress reliever thus making these suitable as an interlayer for reducing the propagation of reflective cracking in hot mix asphalt overlay. The inclusion of geosynthetics in HMA overlays affect the bond between the overlay and existing pavement. The reduction in bond strength between the overlay and existing pavement will lead to delamination of the overlay. This study is going to explain how the bond strength is going to vary for different geosynthetics namely, coir, jute and synthetic interlayered asphalt overlays using finite element analysis. Prony parameters are going to be used to define HMA Property. The cohesive zone model is adopted to define the interface properties in the numerical model. The bond strength of geosynthetic interlayered asphalt overlays at three different temperatures as 10, 20 and 30 °C are going to be evaluated using finite element analysis.

The seismic waves originating from an earthquake source undergoes significant amplification on its way toward the surface. The dynamic properties of the soil such as shear modulus/stiffness degradation and damping play a major role in amplifying the seismic waves. In the present study, two sample bore logs from Calicut have been taken for one-dimensional equivalent linear ground response studies. The bore logs represent clayey and sandy deposits and the shear wave velocity (Vs (30)) of these sites are in the range of 300–360 ms−1(NEHRP C). The uncertainty in the soil properties has been addressed by randomizing the soil profile using Monte Carlo simulation on STRATA. Similarly, the influence of the number of ground motions on the site response has been analyzed by considering different ground motion suites. The regional seismic hazard consistent ground motions have been considered for the analysis. The variation of Peak Ground Acceleration (PGA) along the depth of the soil profile is studied to understand the influence of local soil profile in modifying the wave properties. The influence of variability associated with the input parameters has been assessed through numerical experiments considering multiple numbers of realizations (Vs profile) and ground motions. The study reveals the variability associated with the ground motions to be high when compared to soil property. It can be concluded that the uncertainty in the input motion has a significant impact on the overall outcome of site response analysis.

This paper presents the results from three-dimensional analysis of offshore driven pipe piles using FLAC3D (Fast Lagrangian Analysis of Continua in three Dimensions) program. The numerical model was developed with solid elements for both the pile and the surrounding soil. Interfaces are created both on the inside and outside surfaces of the pipe pile along the length as well as at the bottom of the annular area of the pile. The pile driving was simulated by giving hammer impact force of one blow which was measured during offshore pile installation. Parametric studies were performed with different soil properties until the signals from the numerical analyses matched with the measured force–velocity data of the pile installed in offshore South East Asia region. The results include the soil plug behaviour under continuous driving and with a delay time of 12 h.

For constructing the roads on soft grounds, basal geogrid-reinforced pile-supported embankments are a suitable solution over other conventional ground improvement techniques like preloading, embankment slope flattening, removing and replacing the soft soil, etc. Many studies are available on these basal geogrid-reinforced piled embankments to understand their behaviour under static loading conditions. But it is necessary to understand the behaviour of these geogrid-reinforced piled embankments under seismic excitations. Hence, finite element analysis of three-dimensional models of embankment having crest width of 20 m, height above ground of 6 m, with side slopes of 1V:1.5H consisting of pulverized fuel ash, overlying soft marine clay of 28 m thickness is carried out under seismic excitations corresponding to Zone III (IS:1893). Soft marine clay layer is improved by the addition of piles arranged in square grid pattern with 5.75% area replacement ratio. Geogrid with a tensile modulus of 4600 kN/m is used as the basal reinforcement. Initially, the embankment is analyzed without geogrid reinforcement and pile supports. Then, it is analyzed with (i) Basal geogrid (ii) With pile supports (iii) With basal geogrid and pile supports. The influence of various parameters of the embankment on maximum crest displacements, differential settlements at crest, toe horizontal displacements, stresses at pile head and foundation soil between piles and pile bending moment along the depth at peak acceleration are studied. Analysis of results shows that the embankment supported over piles with basal geogrid reinforcement will experience less crest settlements, differential settlements at crest and toe horizontal displacements due to earthquake load.

Bridge piers are one of the most vulnerable structural elements in a bridge system. The past earthquake reconnaissance report showed that the bridge structures with high residual displacements were unserviceable for the future use after a seismic event. Subsequently, post-disaster rescue and relief operations were rigorously affected. Generally, it is presumed that the utmost seismic demand in a bridge will focus in a small zone, which has a maximum inelastic curvature called as its plastic hinge length. As the bridge pier’s plastic hinge zone governs the load carrying and deformation capabilities of the entire pier, hence it has achieved remarkable focus to structural designers for the last decades to improve the ductility of a pier. Shape memory alloy (SMA) is distinctive class of smart materials, which can sustain the enormous amount of inelastic deformations and reappear to its parental shape after removal of stress or loading. Substituting the typical steel reinforcement in the plastic hinge region of a bridge pier with super-elastic SMA could diminish the damages of a pier. The present research is focused on the numerical investigation on circular concrete bridge piers reinforced with SMA rebars in plastic hinge region and rest part of a pier reinforced with conventional steel under the effect of monotonic static loads. The parameters considered in this study are plastic hinge length and material properties of SMA. Nonlinear static pushover analysis is performed to compare the behavior of steel-RC and SMA-RC bridge piers under the effect of monotonic load. The results are presented in terms of base shear, displacement, ductility and limit state performance criteria of bridge piers.

Model tests and the corresponding three dimensional FE analyses using PLAXIS 3D have been carried out to study the behavior of a single pile under combined action of lateral loading and uplift. Cast-iron model piles of 25 mm diameter and slenderness ratios (L/d) of 20, 25, and 30 have been chosen for the study. The variation of ultimate lateral load with pile head deflection with and without different values of uplift load has been obtained to examine the effect of relative density (R.D) of sand, and L/d ratio of pile on the ultimate pile capacity in both homogeneous and layered deposits of sand. Results indicate that the load–deflection behavior is nonlinear for independent lateral and uplift load, as well as in case of combined loading. It has been also found that independent lateral and uplift capacities of piles obtained from numerical analysis agree well with available theoretical and experimental results for the respective cases. Also, under combined action of lateral load and uplift, increase in lateral load capacity has been found to occur with increase in uplift load for a given L/d ratio, both in homogeneous and layered soil. It has also been observed that for any given L/d ratio, the ultimate lateral capacity decreases for a particular uplift in case of layered deposits when the thickness of topsoil layer (of lower R.D) increases.

Undrained shear strength of saturated clays is a vital property in geotechnical engineering practice. If any relationship between shear strength of soil and index properties of soil is developed, it would be exceptionally alluring. A few endeavors have been made in the past to associate shear strength with Liquidity Index. The Liquidity Index requires the estimation of plastic limit calculated by Casagrande [1] thread rolling method which does not provide the correct assurance of plastic limit of the soil particularly in less plastic soils. Shear strength variation with water content does not follow a regular trend, which makes the analysis difficult. It has been observed in the past researches that shear strength of soil correlates very well with the consistency limits of soils. The present paper develops the correlation between shear strength and Water Content Ratio (wX) and between shear strength and Liquidity Index, to find out the better parameter to evaluate shear strength between Water Content Ratio (wX) and Liquidity Index. The experimental results on three different highly compressible soils having water content ranging from 5% to 25% showed that the regression coefficient value of relation between undrained shear strength with Water Content Ratio came out to be closer to one compared with Regression coefficient value of relation between undrained shear strength with Liquidity Index, for the soils of same geological origin. Liquidity Index variation with Water Content Ratio suggests that there is a definite relation between Liquidity Index and Water Content Ratio and Liquidity Index can be substituted by Water Content Ratio. However, the results obtained from both are more or less same for the soils irrespective of their origin.

Highway and railway embankments form a major part of infrastructure in the transportation sector, but often these embankments rest on weak and problematic deposits with low load-bearing capacities and are prone to high settlements. An attempt has been made to study the performance of an embankment constructed over a weak organic deposit, namely, peat with granular columns as foundation elements. Granular columns have provided effective and promising solutions for flexible loading conditions, especially with soft soils. This ground improvement technique along with geosynthetic encasement is used in the numerical study in assessing and comparing the performance of the embankment in relation to stability. Some parametric studies are also conducted by varying the soil properties say cohesion of the in situ deposit, friction angle of granular column, spacing of granular column, etc., to understand the failure mechanism due to slope instability. The findings from the numerical study revealed the improved performance of embankments founded on geosynthetic encased granular columns.

In recent years, there is a continuous rise in construction activities in the field of civil engineering. The life of a structure depends on the initial strength and the maintenance of construction. The effects on infrastructure due to aging, deterioration, and extreme events are associated with the realization of the need for advanced structural health monitoring (SHM) and damage detection tools. Civil engineering structures such as bridges have a long design life and, therefore, unavoidably come across physical aging and deterioration. Through this SHM technology, early detection of structural damage and examination of the structural integrity is possible with a resultant optimization of maintenance of bridges. The electro-mechanical impedance (EMI) technique is a recent method that is comfortable to implement complex structures with simple instrumentation and direct results. In this research work, a case study of bridge model is considered for SHM in determining damage severity and its location for moderate to severe damage. Also, the same technique applied to the existing bridge for structural health monitoring. From results, it was concluded that the presented methodology was capable of monitoring the existing bridges and also shows good efficiency in determining damage severity and its location. There are noticeable changes in frequencies for moderate to severe damage. Hence, this technique is suitable for the prediction of the presence of damage and its location.

Enzyme-induced carbonate precipitation (EICP) is a novel, bioinspired soil stabilization technique in which calcium carbonate ($${\text{CaCO}}_{3}$$) crystals are enzymatically precipitated to cement and link the soil grains, thereby improving the shear strength of the soil. This work aims to analyze the effect of incorporating $${\text{Mg}}^{{2+}}$$ ions on crystal morphology and their direct influence on the mechanical properties of the soil. A beaker experiment conducted by mixing urea, urease enzyme and $${\text{MgCl}}_{2}$$/$${\text{CaCl}}_{2}$$ in different molar ratios revealed that the increase in the $${{{\text{Mg}}^{{2+}}} \mathord{\left/{\vphantom {{{\text{Mg}}^{{2+}}} {{\text{Ca}}^{{2+}}}}} \right. \kern-0pt} {{\text{Ca}}^{2 + } }}$$ molar ratio decreases the amount of precipitated mass. The soil specimens for unconfined compressive strength (UCS) test were prepared as per its maximum dry unit weight ($$\gamma_{\text{dmax}}$$), and an optimum solution content ($${\text{w}}_{\text{opt}}$$) consisting of urea, urease enzyme and $${\text{MgCl}}_{2}$$/$${\text{CaCl}}_{2}$$ at various $${{{\text{Mg}}^{{2+}} }\mathord{\left/{\vphantom {{{\text{Mg}}^{2+}} {{\text{Ca}}^{2 + } }}} \right. \kern-0pt} {{\text{Ca}}^{2 + } }}$$ molar ratio. Field-emission scanning electron microscopy (FESEM) and X-ray powder diffraction (XRD) tests performed on precipitated mass verify the influence of $${\text{Mg}}^{{2+}}$$ ions on crystal morphology and the occurrence of other carbonates (dolomite) and polymorphs of $${\text{CaCO}}_{3}$$. The results of the UCS tests show that the lower molar ratio of $${\text{Mg}}^{{2+}}$$/$${\text{Ca}}^{2 + }$$ can significantly improve the undrained shear strength of the soil.

Nowadays due to rapid industrialization and urbanization the world facing massive problems such as shortage of natural construction material and increase in the plastic waste. It is essential to manage both problems as early as possible. The purpose of this investigation is to examine the custom of waste plastic as a coarse aggregate in the concrete mix of M20 grade concrete in a fractional way. In this investigation, the seven mixes are prepared by using plastic waste as a coarse aggregate. In the present study, the natural coarse aggregate is exchanged by plastic coarse aggregates’ in various percentages such as 0, 2, 3, 4, 5, 6, and 7%. Various concrete specimens are casted and tested by considering this percentage to find out the interpretation of recycled plastic as a replacement of coarse aggregate that would affect the development of strength in the concrete. It’s observed that up to 5% replacement of ordinary coarse aggregate by plastic coarse aggregate the compressive strength of concrete will increases, after 5% it starts decreasing. Also, the tensile strength of concrete increases up to 4% and after that it starts decreasing. The additional tests are conducted to check the density of concrete and it is was observed that an increase in the percentage of plastic will decrease the density of concrete.

Analysis of stability of a slope becomes important to predict the failure of a natural or manmade slope. Among several factors which trigger failure of a slope, earthquake in presence of groundwater may be quite significant. This paper studies the failure of embankment slopes under different seismic conditions with variable groundwater levels. Three embankments of different heights have been considered and their analyses have been performed by varying slope angle, embankment soil properties, and groundwater levels. The current study contains probabilistic approach of slope stability by assigning an uncertainty range of density and shear strength parameters of embankment soil. Thus the current study considers input variables like height and angle of slope along with three soil properties: bulk density, cohesion, and angle of internal friction of embankment soil. In each case three groundwater levels have been considered. Out of all these variables 50 numbers of random variables for each of bulk density, cohesion, and angle of internal friction of embankment soil have been generated within some specified uncertainty bound with the help of Monte Carlo simulation. Finally, results have been presented in the form of variation of factor of safety with slope geometry and seismic intensity levels for different positions of groundwater levels. The study finds different slope geometry and seismic conditions along with variable groundwater levels affecting the outcome of slope stability analysis quite substantially.

Rainfall is one of the major causes of slope failures occurring in residual soils, which are of concern to geotechnical engineers. Naturally, soil is non-homogeneous in nature with different mechanical and hydraulic properties such as shear strength, soil–water characteristic curve, saturated permeability and unsaturated permeability functions. Negative pore-water pressure or matric suction plays an important role in the evaluation of stability of earth slopes. With rainfall infiltration, the pore-water pressure changes and hence affects its stability. A numerical model of a two-layered non-homogeneous slope is prepared with different hydraulic properties. An unsaturated seepage analysis with infiltration is performed in the finite element framework. With the pore pressures obtained from the seepage analysis, a finite slope stability analysis is performed in the limit equilibrium framework. The pore-water pressure profiles of the two-layered slope are studied with different rainfall intensities. The negative pore-water pressures are reduced to zero at a much shallow depth for higher rainfall intensity, thus reducing its safety factor rapidly. It is also observed that at high rainfall intensity, the two-layered slope suffers a shallow slope failure.

This paper investigates the behavior of an embankment resting on soft clay reinforced with prestressed geogrid encapsulated in thin layer of granular soil. Over-excavation and replacement by geosynthetic reinforced granular soil is an effective technique to improve the load-settlement behavior of embankments resting on soft soil. The effectiveness of geosynthetic reinforcement embedded in clayey soil is very less due to poor interfacial strength and buildup of pore water pressure. But now the availability of granular soil is very less and it makes the reinforced soil technique uneconomical. It is also well established that geosynthetics demonstrate their beneficial effects only after considerable settlements. Thus, there is a need for a technique which will improve the bearing capacity without excessive settlement of reinforced granular soil. One technique yet to be comprehensively studied is prestressing the geosynthetic and encapsulating it in a thin layer of sand when used as reinforcement in clays. A series of finite element analyses are carried out using the FE software PLAXIS 2D to investigate the influence of prestressing the geogrid and encapsulating it in thin layer of sand on the load-settlement behavior of embankment foundations. The influence of prestress on the interaction between geogrid and granular soil is investigated by carrying out large-scale direct shear tests. It is observed that the load-settlement behavior and the interaction between geosynthetic and granular soil can be significantly improved by prestressing the geosynthetic reinforcement.

Rapid development in infrastructure facilities in urban areas requires engineered slopes for various applications. Geotextile-reinforced slope is one of the engineered slopes that is being used more than three decades. Generally, geotextile-reinforced slopes are designed high and steep due to limited space available for the construction of slope in urban areas. Increase in height as well as slope inclination and other parameters influence the stability behavior of geotextile-reinforced slopes. In the present study, the stability of geotextile-reinforced slope (β = 80°) was carried out to understand the influence of various parameters such as: cohesion (c), angle of internal friction (ϕ), vertical spacing of geotextiles (Sv), length of geotextiles (Lg), ultimate tensile capacity of geotextile materials (Tu) and loading conditions (F). In addition, three reinforcement patterns were studied. They are: (i) gradual increase in length of geotextile from top to bottom of the slope (Pi); (ii) gradual decrease in length of geotextile from top to bottom of the slope (Pd); and (iii) uniform length of geotextile from top to bottom of the slope (Pu). In all these three cases, the total length of geotextile layers was maintained the same. The stability analysis of geotextile-reinforced slopes was performed by limit equilibrium method using OASYS SLOPE software, and Bishop slip circle method was adopted for the same. It was observed that for various reinforcement patterns (Pd, Pi and Pu), identical factor of safety can be achieved by reducing total length of geotextile up to 14%. Moreover, to achieve alike factor of safety, angle of internal friction needs to be increased less as compared to cohesion of soil.

Rapidly increasing infrastructure demands more ground availability to transfer the stresses safely. Scarcity of good bearing soil at infrastructure site requires improvement/modification in the soil properties to allow further construction activity mainly in fine-grained soils. This paper presents application of polypropylene fibres (PPF) for stabilization of expansive soil procured from Bhestan near Surat, South Gujarat. During the study, PPF in proportion of 0.75, 1.5, 2.0, 2.25 and 2.5% have been mixed randomly with soil. Various tests were performed to study compaction characteristics, soaked California bearing ratio (CBR) and unconfined compression of virgin soil samples and soil samples with above-mentioned PPF contents. Results showed that addition of PPF reduced maximum dry density in the range of 3–6.5% and increased optimum moisture content in the range of 2.3–5.25%. Also, mixing of PPF (10 mm fibre length) up to 2.25% increased soil CBR from 1.54 to 5.75%, which decreased on further addition of PPF. Increase in PPF fibre length from 10 to 30 mm further increased CBR from 5.75 to 7.06% for same PPF content. In addition, the unconfined compressive strength of the soil was observed to increase by 56.9% at 2.25% PPF. Results highlighted that soil stabilization using PPF is quite useful for modifying properties of cohesive soil.

Industrial steel structures supporting thermal Zero Liquid Discharge (ZLD) are subjected to great lateral forces due to wind and an earthquake. Industrial steel structures are made out of number of joints and structural members, this complicated structural system has to be designed carefully. Strength and performance of these structures for the various combinations of load, geometry, and boundary conditions have to be ascertained before erection. In the present investigation, analytical procedure has been carried out to know the response of various lateral force resisting systems such as “X”, “Inverted V”, “K”, and “Knee” bracings and “Moment Resisting Frame” under high (Zone 5) and low (Zone 2) seismic zones. Response spectrum method of seismic analysis has been used for the study using STAAD Pro V8i software. The various parameters such as fundamental time period, lateral displacement, and storey shear among various structural systems are compared. From the results, it was found that Inverted V bracings show better performance under both high (Zone 5) and low (Zone 2) seismic zone. Further Inverted V bracing is found to be the most efficient structural system for ZLD structure compared to other lateral force resisting systems.

To assess the durability of a liner material, it is important to study its chemical compatibility. In an attempt to define the hydraulic conductivity characteristics of clay liners, use of normal water is far from being representative of the in situ conditions. Therefore, the influence of chemical solutions (inorganic) of different concentrations on hydraulic conductivity of fly ash–bentonite mixtures used as hydraulic barriers was examined. The bentonite content in the fly ash–bentonite mixture was taken up to 15% @ 5% increment starting from 5%. The permeant solutions used include NaCl, NaOH and HCl, at different concentrations, i.e. 0, 0.01, 0.1, 0.5 and 1 M (where ‘M’ represents Molarity), which were chosen to best represent the acidic, basic and neutral nature of the landfill leachate as well as to better portray the effect of monovalent cations present in the in situ landfill leachate. Based on the test results, NaCl proved to have more effect on hydraulic conductivity than NaOH and HCl, considering an overall increase in hydraulic conductivity. Irrespective of the nature of the permeant solution (acidic/basic/neutral), the hydraulic conductivity of all the fly ash–bentonite mixtures increased with the increase in chemical concentrations. Thus, hydraulic conductivity of fly ash–bentonite liner material proved to be more sensitive to the permeant solution.

The objective of this paper is to compare the experimental and analytical behavior of exterior beam–column joint sub-assemblages with transverse reinforcements detailed as per IS 456. Eight-storied reinforced concrete building located in Chennai (Zone III) has been modeled and analyzed in STADD Pro software. The earthquake analysis and design has been carried out as per IS 1893 and critical exterior beam–column joints were taken for study. A one-third scaled model, detailed as per IS 456 and SP 34 was taken for analyzing the effect of lateral force and axial load on the behavior of beam–column joints. A numerical study was carried for scaled model using the finite element software ABAQUS to study the real physical behavior of beam–column joint structure. A concrete damage plastic model is assigned for the finite element model in ABAQUS. Seismic type loading is applied at the end of the beam in order to develop moments at the beam–column joint region. The specimens are retrofitted with the addition of new concrete at the joint region and tested for its load-carrying capacity.

The mechanical response of a granular system depends on various factors at macroscopic (continuum scale) and microscopic (grain scale) levels. Interlocking between the aggregates is one of the microscopic features that affect the response of granular assembly. The present study deals with the study of the effect of aggregate shape on interlocking. Aluminum rods of circular cross-section are used as the basic elements idealizing the aggregates under plane strain conditions. A biaxial compression setup is fabricated. The load is applied vertically at a constant displacement rate and the lateral displacements of the vertical walls are measured. These vertical walls are partially restrained by horizontal springs. The stiffness of the rod assembly and the translation and rotation of some selected rods are considered as the surrogate parameters indicative of the degree of interlocking. Rods with square or triangular cross-sections are used as intrusions, at various area percentages. The present study suggests that, in general, the stiffness of assembly increases, and translation and rotation decreases as more angular particles are used in the assembly. However, no appreciable difference in the response is observed between the two types of angular particles (that is, rods with triangular and square cross-sections) used in the present study.

Shear wave velocity is the most widely used parameter for microzonation studies, site characterization, groundwater engineering, and environmental studies. Field techniques for the measurement of shear wave velocity are generally not economically viable due to deficiency of skillful personnel or unavailability of equipment. The importance of this study is to develop the empirical correlation between standard penetration resistance value (SPT-N) and shear wave velocity (Vs), for Allahabad, U.P, from the existing correlation developed for other cities of India for all soil condition using regression analysis. In this study 83 borehole data is used to calculate the average shear wave velocity (Vs) for Allahabad city at depths of 1.5, 3, 4.5, 15, and 30 for all soil condition. Also average shear wave velocity map for 30 m depth has been plotted and is used to classify the study area as per IBC-2009 (International Building Code). Results show most of the sites fall under C and D category representing soil conditions.

In developing countries like India, due to fast urbanization and rapid development of infrastructure resulted in the use of soft and weak soils around for various Civil Engineering applications. The mechanical behavior of such nature of the soil has to be improved by employing stabilization and reinforcement techniques to make it reliable for construction activities. The black cotton soil is one of the major issues in India. BC soils when exposed to variation in moisture content they undergo high swelling and shrinkage making it more complicated for engineering point of view. The present study investigates the feasibility of controlled low strength material for stabilizing BC soils. The ACI-229R report describes controlled low-strength material (CLSM) as a cementitious material having compressive strength less than 8.3 Mpa (28 days). For the present study, a new greener CLSM comprising Class F fly ash, Cement, Common effluent treatment plant (CETP) Sludge, and Water was developed. The flowability and unconfined compressive strength test was carried out. It was observed from the experimental result that the maximum flowability was 19.8 cm for GF6 and maximum UCS value 0.259 MPa for GF7 mix. After finding the optimum mix, experimental work was carried out by mixing controlled low strength material with black cotton in different proportions. The CBR test was conducted to assess the strength gain of BC soil with different proportions of controlled low strength material and it was observed that there was a reduction in overall flexible pavement thickness of 11% by Controlled low strength material as subgrade stabilization In addition to that, Prediction model was generated using Taguchi’s method of design to avoid the conventional trial and error process. The results indicate that there was an increase in the nconfined compressive strength by increasing the (B/W) ratio.

In the present study laboratory experiments were conducted for the strengthening of locally available river sand of Bhima river (Maharashtra, India) using sword bean extracted as a urea catalyst in place of microorganisms like Sporosarcina pasteurii, which leads to decomposition of urea into ammonia and carbonates. As a calcium source, calcium hydroxide and calcium chloride were considered and mixed separately with sand to observe precipitation of calcite within the matrix of sand. At room temperature, sand matrix with the extract of Sword bean was compacted into a cylindrical specimen and cured for four days and similar specimen without plant extract (virgin sample) was prepared for comparison. With different calcium sources and amounts of urea, unconfined compression tests (UCS) were conducted on treated and untreated sand. It is observed that, with increasing amounts of urea, increase in the UCS for the specimens having calcium chloride has enhanced considerably compared to calcium hydroxide. Sand treated with extract of sword beans has shown higher increase in UCS (324 kPa) as compared to that of without plant extract. It was observed that, calcium chloride is a more effective calcium source when compared with calcium hydroxide.

Fly ash, a waste product from coal combustion, is posing disposal problem all over the world. It is being used in various civil engineering works such as in embankment works and fill materials, etc. The strength of fly ash is very much less compared to the natural soils and hence needs to be improved. A relatively new method of injecting bacteria to bind the soil particles known as Microbial Induced Calcite Precipitation (MICP) was proven to be very effective in the stabilization of poorly graded sands. In the present study, an attempt is made to study the effects of bio-treatment of fly ash using the Sporosarcina Pasteurii to promote calcite precipitation from urea hydrolysis. Single staged injection was adopted for introducing bacteria into the fly ash. A standard bacterial cell concentration and varied urea-calcium chloride were adopted for treating fly ash specimens. Unconfined Compression Strength tests (UCS) revealed an increase in strength ranged from 41.19 to 183.31 kPa. Approximately one order of magnitude reduction in the coefficient of permeability values was observed.

The swelling and shrinkage phenomenon in expansive soil is one of the major causes of infrastructure distress for decades. The soils with montmorillonite as primary mineral composition possess property of excessive volumetric variation during drying and wetting of soil. The volumetric changes depend on proportion of clay mineral available, their exchangeable ions, and internal microstructure. The construction of structures on expansive soils experiences tilting, total and differential settlements resulting in cracking of building and basement walls, upheaving of rigid and flexible pavements, cracking and failure of utility lines, and damage to doors and windows. In order to understand the behavior of expansive soil and to determine the extent of damage that may occur many studies have been conducted in the past. Further, to categorize the extent of damage and type of distress that can occur due to expansive soil and probable remedial measures that can be helpful to mitigate swelling pressure, large amount of literature is available. This paper reviews the state of the art research related to different types of distress caused due to expansive soil, severity of cracking damage, remedial measures, and points to be considered while selecting remedial measures for expansive soils.

Infrastructure and facilities built on structures retaining backfill cause significant damage due to large displacement of retaining walls during excessive vibration. The smart materials can be provided to compensate for the deleterious effects of vibration. Smart materials, namely Lead Zirconate Titanate also known as piezoelectric ceramic (PZT) material, are used to minimize the displacement due to the induced vibration and to control the flexible retention system for granular materials. The solution of the displacement control of retaining walls of varying flexibility is indeterminate in a multivariate system. The excessive vibration may reduce the life span of a retaining wall and may get transferred to the critical locations inducing plastic uncontrolled deformations. This paper investigates the response of smart material to control vibration by means of input transformation techniques. The time-domain formulation exploits the vibration as input and output finite settling time for motion excitation vibrations. The finite settling time depends on the natural frequencies and spring constant of vibration of the flexible retaining wall and granular backfill. The numerical analysis concludes that the provision of piezoelectric ceramic (PZT) material describes the specification of finite-time vibration cancelation. Effect of reduction of vibration by using smart material on the flexibility of the retaining structure is presented.

Earthen dams supporting an upstream reservoir is always associated with the problem of seepage, as water seeks the path of the least resistance through the body of the dam as well as its foundation. Further, due to seasonal rainfall, rainwater can also infiltrate into the earthen dams. Depending on the rate and duration of rainwater infiltration, the stability of the dams is affected. The infiltration of the rainwater into the earthen dams results in the development of pore-water pressures and hydraulic gradients, thus altering the position of the phreatic surface within the embankment, causing consequent deformations. Thus, it is vital to assess the response of earthen dams to the duration and rate of rainwater infiltration during reservoir operating conditions. In this study, considering upstream drawdown conditions, the influence rainfall infiltration on the response of a homogeneous earthen dam has been identified. Coupled stress/pore-water pressure analysis has been carried out for this purpose. It has been observed that the pore-water pressures generated due to the rainwater infiltration adds to the seepage resulting in deformations of the dam faces and reducing the stability of the earthen dams.

The ordinary Portland cement is mixed with various mineral admixtures to produce high strength concrete. Mineral admixtures like microsilica and metakaolin are well-known supplementary cementitious materials. Metakaolin is derived from natural pozollanic material named as kaolin clays; many researchers had tried it to produce high strength concrete. Concrete produced using such natural pozollana and of low water–cement ratio might not have enough water for hydration process. It would affect adversely the properties of concrete. In this study, high strength concrete is produced using metakaolin and mixed with superabsorbent polymer (SAP) to fulfill the demand of water during hydration process. It also examines the effect of SAP on the mechanical properties of concrete. The study includes use of two types of polymers commercially available, namely polyvinyl alcohol (PVA) and polyacrylic acid (PAA). Concrete is mixed with both types of polymers separately. Concrete specimens are cast by using SAP and without SAP and cured under different curing regime conditions. Polymers are added in varying percentages from 0.2 to 1.0% by the weight of cement. The test results reveal that 0.4% by the weight of cement is the optimum dose of PVA which produces strength that nearly equals to the strength of the control mix and for the same dose of PAA, the strength obtained is about fifty percent of the strength of the control mix. As the strength gets reduces by the addition of polyacrylic acid, this paper aims to describe the effect of polyvinyl alcohol and polyacrylic acid in combination on the properties of concrete. The study reveals that use of superabsorbent polymers in combination and in lesser percentages is more effective in water retention and strength enhancement as compared to air-cured mixes (No curing).

During earthquake shaking, pounding of decks occurs in multi-span simply supported bridges (MSSS) when relative displacement between two adjacent decks exceeds the available expansion gap. It may cause the failure of a bridge in various ways such as unseating of the deck, pier failure, bearing failure, and local damage to decks and girders. The damage level of bridge also depends on the distance of the bridge from the fault rupture because the properties of ground motion change with distance from the fault rupture. This paper focuses on pounding probability of a three-span highway bridge subjected to three different types of ground motions, namely, near-field ground motion with pulse, near-field ground motion without pulse, and far-field ground motion along the longitudinal direction of the bridge. Finite element analysis of the bridge was performed in OpenSees considering the nonlinear behavior of piers and bearings. Energy dissipation during pounding of decks was also considered. Incremental dynamic analysis (IDA) was performed to obtain the level of earthquake shaking (i.e., peak ground acceleration (PGA)) required for pounding between adjacent decks. Based on the IDA, fragility analysis was performed to obtain the pounding probability of decks. At a particular PGA level, it was found that far-field ground motions resulted in higher pounding probability as compared to near-field ground motions. When gap size was small, pounding probability for near-field ground motion with pulse was found to be smaller than that of near-field ground motion without pulse. However, when the gap size was large, near-field ground motion with pulse caused higher pounding probability as compared to near-field ground motions without pulse.

Partial infill frames are constructed by filling the bare frame with brick masonry to a certain height throughout the length of the frame. The walls generally restrain a part of the column to deform freely and a leftover portion remains captive which attracts large shear force and shows brittle failure (called captive column failure) during an earthquake, often leading to collapse of the building. Although sufficient experimental investigation has been carried out for infill walls with openings, the same for partial infill frame and recommendations for its modelling in building frame analysis are very limited. This paper collates the performances of partial infill RC frames during major past earthquakes and attempts to provide a review of the major literature on the performance of partial infill frames studied through experiments and numerical models, and their simplified analytical formulations. Further, some available methods to prevent captive column effect are also presented in this paper. The performance of retrofitted partial infill frames, which previously failed due to the captive column effect, studied experimentally by other researchers are also summarised.

Scrap Tire Derived Materials (STDM) mixed with soil are often being used as geomaterials in civil engineering projects for reducing dynamic loads acting on geo-structures and soil liquefaction remediation purposes. On the other hand, any soil dynamic analysis involving STDM needs an estimation of dynamic characteristics of these materials. Predicting dynamic properties of STDM-soil mixture is a complicated task because there are large numbers of factors affecting dynamic properties of mixture, which might have complex relationships with each other within the soil-STDM system. There have been several attempts to evaluate and predict dynamic characteristics of STDM-soil mixtures using simple mathematical expressions. However, all those studies have been focused on case studies of some specific types of STDM and soil mixtures without considering various aspects of their dynamic behavior. This study presents application of artificial intelligence technique in predicting dynamic properties of gravel-tire chips mixtures (GTCM). Two Artificial Intelligence (AI) techniques, Support Vector Machine (SVM), and Artificial Neural Networks (ANN) were employed for modeling shear modulus and damping ratio of TDGM. Test results have shown that shear modulus and damping ratio of the granular mixtures are remarkably influenced by gravel fraction in GTCM. Furthermore, shear modulus was found to increase with the mean effective confining pressure and gravel fraction in the mixture. It was found that a feedforward multilayer perceptron model with backpropagation training algorithm have better performance in predicting complex dynamic characteristics of granular mixture than SVM one.

In this study, the effect of modifying an asphalt binder using Polyphosphoric Acid (PPA) on its rutting performance was studied using the Multiple Stress Creep and Recovery (MSCR) test. The MSCR test provided the non-recoverable creep compliance and percent recovery of the tested binder blends at the test temperature(s). Those parameters were then used to evaluate the stress sensitivity and rutting potential of the PPA-modified binders and were utilized to determine the binder grade based on the level of traffic. For this purpose, a PG 58-28 binder was blended with different amounts of PPA, namely 0, 0.5, 1.0, 1.5, and 2.0% using a high shear mixer. The MSCR tests were conducted at two different stress levels (0.1 and 3.2 kPa) and two different temperatures (58 and 64 °C). It was found that adding PPA decreases the non-recoverable creep compliance of the neat binder. Consequently, the MSCR grade of the neat binder was found to improve from PG58S-XX to PG58E-XX, when blended with 2.0% PPA. Additionally, the percent recovery of the neat binder was found enhanced due to PPA modification. Therefore, it is anticipated that the mixes containing PPA would sustain a higher level of traffic without undergoing a significant amount of rutting compared to mixes containing non-PPA modified binders. Also, it was observed that the PPA-modified binders can exhibit stiffness similar to polymer-modified binders.

In the present work, the dynamic behaviour of combined Piled Raft Foundation (CPRF) in liquefying soils is studied using numerical simulation techniques. Using OPENSEES, 2D poro-elastic modelling of the soil and the piled raft is carried out. The main focus is the pore pressure generation in the soil, caused by the harmonic excitations in horizontal direction on the raft. Due to impervious nature of the raft and piles, excess pore pressures are observed under the raft. This generation of excess pore water pressure can be critical, due to its adverse effects on stability, and this can be very catastrophic without provision of pore pressure relief in the raft. Besides, the poro-elastic horizontal dynamic impedances of CPRFs are reported.

Performance-based evaluation of the building by nonlinear static pushover analysis considering the effects of the soil–structure interaction is the main objective of this study. Soil–structure interaction is idealized by Modified Winkler method and elastic half-space Continuum method. Comparison between fixed base and soil–structure interaction method with raft foundation subjected to pushover analysis is performed using the Standards ASCE 41-13 and ATC-40. In the present study of a ten storey building modeled in SAP 2000 V19.2 software as a three-dimensional frame with and without soil–structure interaction is subjected to Pushover analysis. Totally, nine models are modeled under seismic zone 5 for three types of soil (hard soil, medium soil, and soft soil). The performance point of the building is found using Capacity Spectrum Method. The behavior of the building in the form of hinges defines the state of damage in the structure. The results show that performance of the building is more critical when soil flexibility is taken into consideration.

Original Cam-Clay model and modified Cam-Clay model are both two-dimensional elastoplastic models, which are established in p-q space. Von Mises criterion would be adopted if the above models were applied into simulating three-dimensional stress–strain relationship for soils. It is proved that spatial mobilized plane (SMP) or Lade criterion is more consistent with the yield criterion of soil under three-dimensional stress–strain relationship for soils by test results. A dynamic unified hardening (UH) model is combined with SMP criterion directly or generalized by g(θ) method. The analyzed results have shown that there is volume dilatancy under triaxial extension condition using SMP criterion directly. There are discontinuous yielding surfaces in p-q space using g(θ) method. Finally, the defects mentioned above could be avoided by transformation stress (TS) method. The comparison between model prediction and test results has demonstrated the superiority of TS method.

Lime stabilization continues to be the widely used technique to control the swell-shrink properties of expansive soils. In this paper, results of an experimental study conducted to understand the effect of lime and/or cement on engineering properties of expansive (Black Cotton Soils, (BCS)) collected from Bharuch, Gujarat India are presented. Effect of lime and cement, curing period and specimen preparation on shear strength and compressibility of untreated and treated BCS is studied. Results from the study showed a decrease in LL and the increase of PL with a considerable reduction in PI. Reduction in PI increased with increasing lime content. Physical mixing of soil, lime and/or cement was achieved by two methods: Method 1 (mixture of soil and stabilizer(s) was cured and then specimens prepared and tested immediately) and Method 2 (specimens of treated soil were prepared, cured and then tested). Shear strength increased with curing period in the case of cement. Results show that Method 2 of physical mixing of soil and lime is effective in increasing shear strength and reducing the coefficient of compressibility or compression index. Treatment led to a reduction in swell pressures with magnitude profoundly affected by specimen preparation method and the presence of cement along with Cao. Method 2 of physical mixing of soil and stabilizer(s) was found to be efficient in improving the strength and volumetric behavior of BCS.

The strength and deformation behavior of jointed rock was examined in the context of the design of slopes, construction of tunneling, and mining projects due to the presence of natural hair cracks, fissures, bedding planes, faults, etc. Dolomite rock from Gujarat is used for experimental study to find the shear parameters of proposed rock mass matrix. A different rock matrix is formed with providing the vertical and horizontal cuts in different patterns. A different matrix includes the following vertical cuts, two vertical cuts (perpendicular to each other) passing from center of specimen, three vertical cuts (each at every 60°) passing through center of specimen, and four vertical cuts in grid pattern. With above vertical cuts also all specimens were cut in horizontal plane at every (I) 1/6 of height, (II) 1/3 of height, and (III) 1/2 of height. A different matrix is tested using rock triaxial system. The strength behavior was studied using Hoek–Brown strength theory and Mohr–Coulomb strength theory. Results were compared with intact rock and various jointed rock matrix specimens. Orientation of rock matrix shows little increase in cohesion value and decrease in angle of internal friction with increase in number of joints in vertical direction. The typical failure/deformation pattern was observed in jointed rock matrix specimens such as axial failure, block rotation, splitting of blocks through joints, and shear failure.

Indian seismic code provides expressions to evaluate the fundamental natural period for the seismic analysis of the structures primarily as a function of the height of the building and the length of the structure along the direction of earthquake considered. Building period predicted by these expressions is very useful in practice. Many researchers have performed the studies to evaluate the fundamental natural period of the buildings and found that the different other parameters such as stiffness of the structure, base dimensions, and the number of bays also affect the value of the fundamental time period of vibration of the building. Researchers also found that there is a scope for further improvement in the presently available expressions of time period given in design codes. In this study, effects of the various parameters have been studied and derived an expression to evaluate the time period of vibration.

Design and construction of high embankment or structures on fine-grained and soft soil having poor shear strength parameters have always been a challenging task for engineers which is not only susceptible to higher settlements and shear failures but also in some cases liquefaction. Selection of a proper ground improvement method is the key for economical and sustainable development of any project. With the help of three case studies, this paper intends to present the measures adopted to overcome the complexity faced during the design and construction of such structures for different kinds of soils. This paper also emphasizes on the use of liquefaction hazard assessment and mapping for structures on soils susceptible to liquefaction which is not very much common in contemporary India and explains various measures that can be taken to mitigate it.

The gravity effect of fascia has been neglected in conventional design methods, which results in conservative designs. In this study, an attempt is made to study the effect of fascia gravity on the final design of reinforced soil wall. Along with the gravity effect, the difference in the design methods of flexible faced wall design and rigid faced wall design methods and their impact on the designs is also studied. In this study, it was found that gravity effect helps in reducing lengths of reinforcement by providing resistance in external stability.

Gypsum rich soils, mostly found in arid regions of the world are known to pose and number of geotechnical engineering hazards, the most common one being collapse settlement. In this research, the influence of gypsum content on the shear strength and collapsibility of reconstituted gypsum sands was studied. Reconstituted specimens of gypsum and sand were prepared with varying amounts of gypsum by weight. Direct shear strength tests and single collapse potential tests were conducted on the soils. The study showed that both the angle of internal friction and collapse potential of the soils increased with increase in gypsum content. The addition of water to the specimens brought about a visible amount of cohesion to the specimens, which were otherwise mostly cohesionless when dried. Next, electrical resistivity testing was conducted on the gypsum sand specimens using the four-electrode box resistivity setup. The influence of gypsum content and volumetric moisture content on five specimens was studied and it was seen that resistivity increased with decrease in moisture, but it did not vary significantly with gypsum content. Pore-water resistivity measurements were made to using a conductivity meter. It was seen that, the presence of gypsum had a marked effect on pore-water resistivity but gypsum content itself did not have a major influence on resistivity. The resistivity measurements normalized with pore-water resistivity were then plotted and it was found that soil with no gypsum had a markedly different profile than those of gypsum sands. Regression models were developed to predict the volumetric water content for gypsum and non-gypsum sands.