Geotechnics for Natural and Engineered Sustainable Technologies

Geotechnical and geoenvironmental engineering, which constitutes one of the major tasks of the infrastructure and construction projects, is one of the main contributors to the climate change and other global environmental impacts, due to the use of large amounts of materials and energy. One of the most effective ways to address these challenges is to have the environmental implications integrated into the decisions of a geotechnical/geoenvironmental project. In this regard, the application of life cycle assessment (LCA) has gained major impetus to evaluate the environmental sustainability of such projects. LCA is a comprehensive method for assessing a range of environmental impacts across the full life cycle of a geotechnical and geoenvironmental project, from raw material acquisition, material manufacturing and transport, construction, use and maintenance, and final disposal/recycling. LCA can be challenging due to limited reliable or relevant inventory of data for the assessment. However, it is a systematic and well-accepted tool to develop/design environmentally sustainable geotechnical and geoenvironmental projects. In addition, a triple bottom line assessment which further involves evaluating the economic and social sustainability aspects of the project along with the LCA is essential to holistically evaluate and identify the effectiveness of a geotechnical and geoenvironmental project toward sustainability. This paper presents a review of few studies that demonstrate the application of LCA and triple bottom line assessment to some of the common geotechnical and geoenvironmental projects. The study underscores the importance of LCA in identifying the critical materials and/or operations for the resulting environmental impacts and helps explore different options to improve the net environmental and socioeconomic benefits.

Geotechnical practice conventionally involves investigating a site to characterize it through: (1) in situ testing and (2) laboratory testing of so-called undisturbed samples, and then synthesizing the results to predict the overall response of the ground to engineering intervention. In the recent past, several case studies have been reported in the literature, particularly of soft ground improved by preloading with prefabricated vertical drains (PVDs), with time–settlement plots obtained from data recorded by settlement gauges installed at different depths in the ground. In addition, several load–displacement responses of piles are also available in the literature. This paper complements the above approach of element response to gross one by analyzing the response of the ground to arrive at its gross engineering properties or characteristics. Methods to estimate the compression index, C _c, and the coefficient of radial consolidation, c _r, by back-analysis of observed time–settlement plots of PVD-improved ground are illustrated. Furthermore, an approach to predict the magnitude of desiccation of weathered crust, and quantify the non-homogeneity of soft ground with respect to C _c, is presented. The c _r values estimated from three case histories compare reasonably well with those given by Hansbo (2005). Lastly, a method to estimate the initial shaft and base stiffnesses and the ultimate shaft and base resistances of a pile foundation is presented by considering the soil–pile response to be hyperbolic. Predictions compare well with results obtained from pile load tests (PLTs) performed at three different locations in India.

Soil–structure interaction (SSI) analysis has been recognized to be an essential step in the design of important structures. With the advent of powerful computers, SSI analysis capabilities have increased by leaps and bounds. This article presents recent research on dynamic SSI analysis of pile-supported structures using direct- and substructure-based numerical techniques. Dynamic response of pile foundations is a frequency-dependent problem. Experimental studies as well as numerical simulations, discussed in the article, reveal characteristics of single and group piles under dynamic loads. It was observed that dynamic lateral stiffness of piles is reduced significantly by cyclic loading. Peak displacement amplitude of pile–clay system, under dynamic loads, was observed to decrease significantly when consistency of clay changes from soft to medium stiff. Finite element analyses were able to simulate the frequency response of a single pile, with admissible accuracy. Flexible volume substructuring using the program SASSI 2010, for seismic response of pile foundations, is discussed with two case studies. The substructure-based SASSI analysis is found to produce results which are in agreement with analytical and experimental results. However, the choice of analyses tools for pile-supported structures is to be made after weighing the computational cost and complexity of numerical models.

For sustainable development, it is necessary that various stakeholders, whose needs match, come together and make accelerated efforts toward realizing a recycle economy through active promotion of recycling of industrial by-products or waste. This paper describes some of the research on the effective use of by-products/wastes of other industries in the field of geotechnical engineering with special emphasis on geo-disaster reduction. Recycling of waste tires and disaster mitigation in the context of Japanese experiences are focused here, and various disaster reduction techniques developed in Japan using tire-derived materials are described.

Methods of slope stability analyses for static and seismic conditions are discussed. The ideas of factor of safety, critical acceleration and critical slip surface are examined. The idea of displacement of slopes during earthquakes is also discussed; it is emphasised that displacements are a better criterion for seismic design of slopes. Post-seismic large displacement of slopes is examined in a test case.

Large-scale offshore wind farms have emerged as a critical renewable energy technology to reduce greenhouse gas (GHG) emission and autonomy in energy production. Each of these wind farms consists of many wind turbine generators (WTG) mounted on a support structure and is capable of generating up to (as we write the paper) 1.2 GW of power. These are relatively new technological advancements which are installed in harsh offshore environments. Naturally, the design of foundations for such structures is challenging. Furthermore, WTG support structures due to its shape and form (heavy rotating mass at the top of a slender tower) are dynamically sensitive in the sense that the natural frequency of such system is very close to the forcing frequencies acting on them. The aims of this keynote lecture are as follows: (a) summarise the loads acting on the structure together with its associated complexity; (b) discuss the challenges in designing such foundations; (c) describe the rationale behind scaled models tests that supported the development of offshore wind turbine design philosophy; (d) draw parallel with other geotechnical scaled model tests and discuss the scaling issues; (e) propose a method to scale the model tests for predicting prototype consequences. While there is no track record of long-term performances of these new structures, design and construction of these must be carried out for 25–30 years and it is argued that scaled model tests are necessary. Finally, the lecture concludes that well thought out scaled models tests can be effective in predicting the long-term issues and engineers need to learn from other disciplines.

Use of geosynthetic-reinforced granular beds is getting very popular over the last two to three decades. The cost of geosynthetics has gone done many fold as it is produced in large scales. This has necessitated development of analytical tools for design of reinforced granular beds resting on soft soils which have low bearing capacity and cause large settlements. Some of the basic modeling elements used for modeling soil behavior are being used to develop more complex models for representing reinforced granular bed behavior. This paper reviews the development that has taken place in this area during last three decades. The focus is more on the mechanical models developed for representing the behavior of geosynthetic-reinforced foundation beds. There are models developed for single and multiple layers of reinforcement. These models take into consideration factors such as compressibility of granular material, extensible and inextensible reinforcements, interfacial friction between the geosynthetic reinforcement and the soil, pretension in the reinforcement, time-dependent behavior of the soft soil, shear modulus of the granular bed, the creep behavior of reinforcement, flexural rigidity of the reinforcement, and nonlinear behavior of granular material and soft clay. Most of these models are not yet validated in the field conditions. The major reason for lack of this is that the models are having far too many parameters, and the values of these parameters for any site are not available. Parametric studies carried out using these models have improved the understanding of the behavior of reinforced foundations considerably.

Recent advances in digital technology led to great improvement in understanding and solving many geotechnical engineering problems. This paper presents few important image-based techniques for precise characterizations, applicable to geotechnical engineering and demonstrates the same. Some of the important applications discussed in this paper are particle shape characterization of granular materials, quantification of surface roughness of sand particles, measurement of shear band thickness in direct shear tests and correlating it to the shear strength of soils, and microtopographical analysis of geosynthetic surfaces to understand shear-induced surface changes and correlating them to their interface shear behavior. While experimental measurements fall short to render required accuracy to these problems, image-based studies offer better visualization of underlying mechanisms along with accurate quantifications.

Engineers associated with construction of tunnels in weak rocks are frequently met with geotechnical problems like instability of tunnels, yielding of the rock mass and excessive deformations due to squeezing. The problems are induced due to redistribution of in situ stresses around tunnel periphery caused by excavation of the tunnel. It is a challenging task to have proper understanding of the geotechnical issues before starting the excavation. The present chapter discusses some of the most challenging geotechnical issues which can be resolved in advance with characterisation of the rock mass at the site. These issues include assessing rock mass strength subject to given confining pressure for unreinforced and bolted rock mass, assessment of squeezing potential, assessment of tunnel deformation and expected support pressure. If adequate understanding on these issues is available with the designers, proper strategies may be formulated to handle problems at construction stage.

Geophysical surveys, and specifically seismic tests, provide powerful tools for geotechnical site investigation. Indeed, they cover the whole range of soils and rocks, independently of particle size, and provide data in the natural state for the characterization at different scales. Assessment of the reliability of the most popular techniques is therefore of primary importance for static and seismic applications. This chapter reports some data from recent experiments devoted to reliability assessment at some reference sites, where intra-method and inter-method variability has been studied. The propagation of the measured uncertainties in soil porosity assessment and seismic ground response analyses is also considered to provide an insight on the consequences in the practice of geotechnical engineering.

Cutoff walls used for prevention of the migration of mobile contaminants in the aquifer must maintain high barrier performance for a long period. Soil–bentonite (SB), which is a mixture of in situ soil and bentonite, has many advantages as a barrier material such as appropriate deformability, homogeneity, and material stability because the SB consists only of inorganic soils. To ensure the long-term durability of the SB cutoff walls, various aspects such as performance of constructed barriers and post-construction maintenance need to be clarified. For a decade or more, the authors have studied factors affecting hydraulic conductivity (k) of SB, self-recovery in the k values against occurrence of hydraulic fractures, the feasibility of on-site quality assessment using the piezocone test, and the role of chemical diffusion in transport of mobile substances through SB cutoff walls. These approaches revealed that the k of the SB is affected by chemicals in groundwater and the content of bentonite powder. The piezocone test seems to be a suitable tool for detection of a lean-mix part in the cutoff walls and for measurement of on-site k values. The effect of chemical diffusion on transport of mobile substances is not negligible because the relative concentration of a chemical substance attained 0.26 after 50 years only by the chemical diffusion when not considering adsorption onto soil particles.

The construction of tunnel has a long history from the mining tunnel for minerals to underground passage for transportation. Most of tunnels are being constructed to pass through the high mountain to have a shortcut instead of taking a detour to reach the destination. The geological conditions in the area of tunnel construction work are not all the time favorable condition. The rock bolt and steel rib support systems for tunnel face are described. The tunnel construction in weak rock is described with rock bolt and steel pipe grouting reinforcement (NATM). The advantages and construction procedures of pre-supported tunneling method (PSTM) and tubular roof construction method (TRcM) in soft ground are presented with the detail schematic diagrams. In the latter part of this paper, the field application case histories of PSTM and TRcM are reported for the tunnel construction for road in weak rock and metro station in soft ground, respectively. The field monitoring results during the tunnel construction which underpass through 60-m-long existing railway tracks by using TRcM are also described.

This paper presents a study on seismic soil–pile installation using numerical modeling in conjunction with centrifuge model studies. The numerical analyses were conducted using ABAQUS with a hypoelastic constitutive model for the clay. Numerical analyses were used to extend the range of soil, pile, and ground motion parameters which could not be studied in centrifuge. The dimensionless parameters involving the major parameters such as pile modulus, soil modulus, slenderness ratio, natural frequencies of clay layer and pile-raft, superstructure mass, density of the soil and peak ground acceleration were obtained from the parametric studies. The relationships for the amplification of ground motions and the maximum bending moment in the pile were developed based on regression of the numerical data.

This paper presents short- and long-term influence of EPS geofoam to reduce static and traffic loading induced earth pressures on non-yielding rigid retaining walls. Grade III Indian standard sand and EPS15 geofoam (15 kg/m³ density) are used in model studies, as backfill and compressible inclusion at the interface between the retaining wall and backfill, respectively. Short- and long-term static and traffic loading model tests are performed with and without presence of geofoam. Model retaining wall is instrumented with pressure sensors to measure the lateral earth pressure on wall. Plastic markers are placed along the width of model plate, geofoam, and sand backfill to measure the movement of wall, geofoam compression, and backfill settlement, respectively. Compressive creep (CC) strains of 3% are induced on geofoam samples to simulate pseudo-long-term (PLT) behavior of geofoam. Static and traffic loads are applied on backfill using Servo-hydraulic actuator and surcharge load distribution system. Lateral thrust isolation efficiencies of 55.1–64.2% and 60.6–69.4% are observed under static and traffic loading conditions, respectively, in the presence of geofoam. Higher lateral thrust isolation efficiency, geofoam compression and backfill settlements are observed from the pseudo-long-term static and traffic loading on retaining wall compared to respective initial tests.

Integrated solid waste management plan (ISWMP) developed in Kanpur city involves activities related to waste generation, storage, collection, transport to landfill site, processing (compost, incineration), and final disposal. The waste products generated from various phases of ISWMP which have insignificant reuse capabilities (named as processed waste) have been disposed of in engineered landfills. At times, fresh waste is also being disposed of in separate cells of engineered landfill. As the characteristics of municipal solid waste (MSW) play a major role in the design and proper functioning of waste disposal facilities, it is desirable to understand the variation in the characteristics of the fresh and processed MSW. In this study, comprehensive characteristics of fresh and processed MSW generated in Kanpur city are assessed through gradation, compaction, and compressibility behavior. A significant variation in the characteristic behavior has been noticed between fresh and processed wastes.

Physico-chemical interactions play a key role in understanding the behaviour of clay soils in wide range of geotechnical and geoenvironmental engineering applications. Its significance on the behaviour of clay soils reconstituted from slurries has been well demonstrated in the literature. Compacted soils and natural soil deposits which are unsaturated also come in contact with contaminants in these applications. Therefore, this paper examines the effect of physico-chemical factors on the structure, compressibility and collapse behaviour of compacted soil. Physico-chemical effects were incorporated using sodium chloride and calcium chloride salt solutions as pore fluid and interacting fluid in different combinations. The changes in the soil structure due to the physico-chemical changes were studied using scanning electron micrographs. The experimental results were analysed and discussed with the aid of Barcelona expansive model (BExM) framework in this paper.

Failure and fracturing occur in the rocks when the stresses exceed the threshold limit with the formation of micro-cracks. Subsequent coalescence of several micro-cracks forms a macro-crack leading to failure. The ultimate failure in rocks largely depends on the fracture process and corresponding failure mode. In the present paper, observations on the crack initiation and propagation based on the analysis of failure modes and fracture patterns are reported. Failure strength of the rocks varies with the failure modes and corresponding fracture patterns. Theoretical criteria for rock failure based on crack growth against experimental observations greatly advocated recent years. Moreover, numerical studies on crack initiation and propagation in rocks became very popular in the last decade. This paper presents the complex failure mechanism of rocks with details on crack initiation and propagation characteristics with pre-existing flaws. The study discusses different failure modes in brittle rocks through some laboratory investigation. This paper also discusses some of the numerical simulation results while analysing the crack growth.

Monumental buildings keep experiencing the distresses due to weathering effects or other reasons. Micropiling had been found very useful for retrofitting works (Srivastava et al. in stability analyses of 18 m deep excavation using micropiles. IGC, N, Delhi, 2016). Kolkata High Court building is a beautiful, majestic building, built in 1872, over a large area, along Hooghly River. The North–West (N–W) corner of the building had experienced some settlement in the year 2014–2015. Authors had inspected the building in December 2015 and again in February 2016. The site visit report indicated that there was differential settlement of shallow foundation of building in its N–W corner. Ingress of Hooghly River water up to foundation was one of the possibilities of distress in foundation. The micropiling followed by grouting was found the most appropriate solution for the site. The site solutions shall be instrumented also over a period of 10 years or so, to periodically monitor the settlement, if any, of building after the treatment.

This paper assesses the possible conditions that might have resulted in the recent catastrophic failure of the Meethotamulla landfill slope at Colombo. This paper presents a probabilistic approach to find the different combinations of parameters that might have caused the collapse of landfill slope. A performance function is formulated, and the reliability of the slope is assessed using first-order reliability method (FORM). The factor of safety associated with various slip surfaces are computed with different combinations of mean and COV. The results obtained from the reliability analysis based on FORM agree closely with the reported post-failure investigations. The analysis elucidated the possible causes of landfill slope failure. The outcome of the analysis can be utilized for finding a remediation with improved knowledge about the shear strength parameters of the solid waste. The probabilistic analysis conducted in the present work reveals that the mean value of shear strength parameters of MSW and its associated variability responsible for the collapse of Meethotamulla garbage dump are friction angle, \( \phi = 20^\circ \) and stability number, \( {c \mathord{\left/ {\vphantom {c {\gamma H}}} \right. \kern-0pt} {\gamma H}} = 0.05 \). The reliability analysis proved that the most likely reason for the dump failure is the reduction in shear strength parameters of the MSW. The excessive rainfall might have triggered the reduction in shear strength parameters. The analysis of Meethotamulla garbage dump disaster demonstrated that it is very essential to conduct reliability analysis as realistically as possible to find the conditions that have triggered the collapse.

Attenuation of seismic waves in the frequency domain for near- and far-source sites is the key parameter for inferring source properties, simulating ground motions and hazard analysis. The seismic devastation is directly related to the attenuation characteristics of the medium and the amount of seismic energy released during an earthquake. Based on the detailed literature review, it is observed that studies have been done worldwide to understand the attenuation characteristics by estimating frequency-dependent shear-wave attenuation factor (Q) for inter-plate region but very limited studies have focused on intra-plate region. This research paper focuses primarily on the determination of kappa factor (κ) and quality factor (Q) for intra-plate region as this region has scarcity of observed ground motion data sets. Around 105 recorded ground motions were collected from Canada and USA, monitored by Idaho National Laboratory, USA, during 2005–2015. This data is used to determine the farfield source geometric attenuation, kappa factor and inelastic attenuation of Q-value. An attenuation model of Fourier spectral amplitudes for a shear window for both horizontal and vertical components is also determined. Stochastic simulation of the ground motion records using EXSIM was carried out and very well comparable with the recorded ground motion data. It is also observed that spectral analysis of the ground motions shows a reliable match between the simulated and recorded spectra which supports the validity of the source parameters derived in this study. Also the results show that coefficients developed from vertical components are not applicable for horizontal components. Developed parameters kappa and quality factor are very well comparable with existing relationships from the literature. These parameters developed by considering the large data set from USA and Canada can be used for a wide intra-plate region.

Surface wave methods which utilize the dispersion property of Rayleigh waves are widely used for subsurface site characterization. As a non-invasive method of site characterization, it has many advantages over the invasive methods of geotechnical site characterization. Surface wave methods determine the small strain shear modulus of near-surface materials, and this shear modulus is the key input in the evaluation of the soil response under dynamic/seismic loading. So, the accuracy of testing is very important, otherwise it may lead to significant consequences on the seismic hazard studies. There are different uncertainties associated with surface wave methods. These uncertainties can be broadly classified into three categories: Model-based uncertainty, Data measurement uncertainty, and Inversion uncertainty. Model-based uncertainty basically contains the near-field effects which lead to the underestimation of Rayleigh wave phase velocity. Data measurement uncertainty is another major source of uncertainty, which arises while conducting the surface wave tests due to the noise present in the surroundings in the form of continuous or transient signals. Noise results in a scatter in the measured dispersion curve and this scatter in the dispersion curve may provide different velocity profiles, which are falling in the range of measured data variation. Inversion uncertainty deals with non-unique solution of inversion. Non-unique solution may results into several equivalent velocity profiles, with a good fit with the experimental dispersion curve. Now, the consequence of this data measurement and inversion uncertainty may show significant variation on ground response analysis.

Flooding can cause extensive damages in roadways, particularly in those with granular base layers and thin asphalt mix surface layers. The objective of this paper is to present a summary of work conducted on the evaluation of the impact of flooding on pavements. Research shows that flood-induced damage occurs through various ways—weakening and washing away of granular base and soil subgrade layers, washing away of thin surface layers such as seals, and through erosion of subsurface materials near flowing water. Dislocation of concrete slabs due to washing away of subgrade soils during flooding has also been noted. Several models and frameworks have been developed to predict change in structural and surface properties such as roughness due to the impact of flooding. A number of models relating resilient modulus of soil to saturation and matric suction have been proposed. Researches have use both finite difference and finite element models to simulate flow of water through pavements. It has been confirmed that flow under unsaturated conditions is the dominant drainage mechanism in pavements. The role of base course material properties, trench backfill material, and drainage systems has been found to be crucial for drainage. The importance of considering the soil water characteristic curve information and an understanding of change in hydraulic conductivity for different saturation conditions has been emphasized.

Civil infrastructure systems, especially geotechnical assets, are vulnerable to climate change, and natural and man-made disasters. Resilience, which is the ability of a system to absorb, recover from, and adapt to disruptions so that the consequences are minimized, introduces a new paradigm to overcome challenges related to infrastructure vulnerability against disasters. Consideration of sustainability in conjunction with resilience in infrastructure asset management ensures that human interventions of building resilient infrastructure systems are in harmony with the natural environment and with the aspirations of the present and future generations. A quantitative framework for the assessment of resilience and sustainability of geotechnical infrastructure is developed based on the Driver–Pressure–State–Impact–Response (DPSIR) framework. The new framework is demonstrated through an example problem based on a selected road network in the province of Ontario, Canada.

The utilization of Jack-up rig for offshore exploration is significantly higher over the last decade and hope to increase in future despite the low oil prices for the last couple of years. Good prediction of spudcan bearing resistance in a problematic soil profile can shed light on precautionary measures that a rig contractor can adopt to facilitate a safe installation of spudcan. Nonetheless, the accuracy of the prediction is limited by the reliability of the interpreted soil strength parameters, lateral variability as well as the validity of the design method currently in use. It is imperative that high quality of sampling and testing methods is adopted, to evaluate the stratification/strength and arrive at a reasonable design profiles. This in aid of geophysical surveys will assist in evaluating the potential risks and the measures to mitigate the same.

Water storage tanks of diameter 30 m and height 14.50 m were erected at a site near the coastal region of West Bengal. Detailed soil exploration work revealed that the deposit consisted of typical soft marine clay with standard penetration (SPT) values lying in the range of 2–6 up to 28.0 m depth below the ground level. Varying percentage of decomposed vegetation and laminated silt was observed between 11.50 and 28.00 m depth below EGL. Overall ground improvement was proposed, and accordingly, stone columns were installed up to the depth of 10.00 m below EGL. After one year of installation, total settlements of 800 mm and differential settlement of about 150 mm were observed and these have been continuing unabated. Subsequently, detailed forensic investigation was made, and it was observed that the stone columns had showed telltale signs of failure, and consequently, huge settlement resulted. The present paper discusses on the various causes of failure and suggests some remedial measures for arresting the settlements.

Risk assessment and management of flow landslides require a reliable estimate of the runout of the landslide masses. This paper introduces empirical and analytical models for the prediction of the runout of flow landslides. The numerical model uses an extension of the Bing model in Eulerian coordinates with two-space dimensions and implements the full Herschel–Bulkley rheology to dynamically compute the depth of the moving material and shear layer. The models are validated by comparing them to the observed runout values for the Kattmarka flow landslide that took place in Norway in 2009. In particular, the analytical model, although still under development, shows promise.

The possibility to quantitatively measure changes in state variables both in laboratory and in situ is the key for the comprehensive assessment and understanding of many problems in geotechnical engineering. The analysis of the processes in unsaturated soils, for example, requires not only pore water pressures but also the information on the water content and the porosity to capture the field soil–water retention relationships. In saturated soils, knowledge of the temporal evolution of the soil density allows a much better understanding of the consolidation and shrinkage behavior, especially with respect to soft soils. Electromagnetic measurement methods allow the quantification of not only the water content but also the porosity of granular and cohesive soils. In particular, the porosity, which determines the dry density of a soil in combination with the specific gravity, is a key parameter influencing many mechanical and hydraulic processes and their governing parameters. The presented contribution introduces different measurement methods in the laboratory and the field for determining water content and density using a variety of sensors.

Geocells are geosynthetics which are essentially three dimensional and have a rhomboidal cellular profile. Geocells with engineering applications, now made in India, are fabricated from textured HDPE straps which are welded together. For major applications, the geocells are judiciously perforated for drainage/porewater pressure relief and cell-to-cell infill interaction. The geosynthetic is versatile and can be utilised for a variety of geotechnical applications, broadly load bearing and protection against erosion. The profile of geocells for these two broad applications differs; the geocell for load bearing is deeper and has closer weld spacing. This paper highlights application of geocells in roads, specifically rehabilitation of a road, and embankment slope protection, both cases in Assam, Churaibari and Bogibeel. Both these studies relate to corrective measures taken after a series of fiascos, one of these of a major nature. In both cases, geocells were quite rapidly installed. While the solutions were executed on an emergency basis, no further work was required to be done and the solutions proved to be long term. This paper also attempts to highlight that geocells need not be a part of a disaster management system but can and should play a major role as part of the designed system for highways with several inherent advantages.