A. Murali Krishna

• Ph. D
• Professor and Dean at Indian Institute of Technology Tirupati

Experimental investigations were conducted using laboratory physical model tests to examine the behaviour of circular footing (diameter, D = 150 mm) resting on sand-tyre shred mattress overlying soft clay soil (undrained shear strength, Cu = 14.5 kPa), with and without geogrid reinforcement at the interface of soft soil and sand-tyre mattress. Resu...

The growing global issue of waste tyres, which are non-biodegradable, poses serious environmental risks, with improper disposal and burning contributing to air and water pollution through the release of harmful chemicals and greenhouse gases. However, waste tyres possess unique engineering properties such as high tensile strength, permeability, dur...

This study investigates the pore-water pressure increase associated with rainfall intensity and duration on a coal ash embankment slope and its effect on the slope stability for safe disposal and storage of coal ash storage facilities (CASFs). Several worldwide incidents during the last decades have revealed that rainfall-induced reductions in matr...

Rainfall-triggered landslides are a major geohazard in the Guwahati region which cannot be convincingly addressed by conventional slope stability approaches. This study attempts to address this issue with the help of advanced analysis considering the concepts of unsaturated soil mechanics involving transient/steady-state phenomena aided by the vari...

Soil liquefaction is a dangerous phenomenon that involves huge damages during strong earthquake ground motion events. Stone columns (SCs) are widely used as a liquefaction mitigation element which is expected to perform improvements against liquefaction hazard by densifying, increasing the stiffness and rapid dissipation of excess pore water pressu...

Assessing the dynamic response of soft and compressible soils is a prerequisite for many earthquake geotechnical engineering applications. Dynamic characterization is represented in terms of strain-dependent dynamic soil properties (Gmax, G/Gmax, and damping ratio-D variation with shear strain-γ) and liquefaction potential. The current study aims t...

In this paper, numerical study results that highlight the capability of using pond ash as a cover material in covers with capillary barrier effects are succinctly summarized. A model was exclusively developed and calibrated using commercial software SEEP/W for this study. After calibration, the efficiency of pond ash as a coarse-grained layer (CGL)...

This paper reports a comparative influence of the two different types of loading mechanisms on the frequency-dependent dynamic properties of the cohesionless Brahmaputra sandy soil. The shear modulus and damping ratio of the chosen soil are largely influenced by the loading frequencies of the two different testing types. Based on the strain-control...

This article presents an integrated approach for seismic analysis of pile foundations and demonstrates the applicability through an example. The approach involves various steps starting from identifying the seismic sources, analyzing local soil conditions, ground response analysis, and dynamic analysis of pile foundations. The complete nonlinearity...

Hill slopes within the city of Guwahati comprises mostly unsaturated residual soils The assessment of potential susceptibility to rainfall-induced landslide is governed by an effective modelling of the changes in matric suction in response to rainfall infiltration. This study presents the assessment of the rainfall-induced landslide susceptibility...

Reinforced-soil walls offer an excellent solution to many problems associated with earth-retaining structures, especially under seismic conditions. This paper presents the seismic response of wrap-faced reinforced soil-retaining walls through numerical models. The development of numerical models for simulating shaking-table tests on wrap-faced, rei...

In the present study, stability analysis of an unsaturated homogenous pond ash slope subjected to rainfall using the limit equilibrium method based n Bishop and Morgenstern-Price methods under steady-state seepage and transient seepage conditions was carried out. Seepage and stability analyses were carried out using SEEP/W and SLOPE/W models, respe...

The use of soil-nailing is one of the methods adopted for the stabilization of slopes and supporting the deep excavations. Many design guidelines and manuals suggested the suitable and favorable conditions for the application of soil-nailing techniques, among which groundwater level is the main concern. But most of the studies failed to show how th...

Piles are generally used to carry both vertical and horizontal loads. For small lateral loads, the piles response is evaluated separately without considering their possible interaction of both lateral and vertical loads. In the construction of several offshore structures, the lateral loads are comparatively high where the combined effect of both ve...

Earthquakes often cause significant human loss and infrastructural damage. Infrastructural losses can be minimized through adopting efficient earthquake-resistant design considering dynamic soil–structure interaction (DSSI) effects. The DSSI can be dealt only upon realizing the response of soils to dynamic loads. Nonlinear ground response analysis...

This volume comprises the select proceedings of the Indian Geotechnical Conference (IGC) 2020. The contents focus on recent developments in geotechnical engineering for sustainable tomorrow. The volume covers the topics related advances in ground improvement of weak foundation soils for various civil engineering projects and design/construction of...

Low tensile strength of soils makes them unsuitable for constructions where soils are subjected to tensile loads. Earthquake loading on soils impose compression and tension loading cycles during which there is a high possibility of failure in geotechnical structures like embankments, slopes and retaining walls. Geosynthetics come to rescue in many...

The response of any structure depends on its regional seismicity, source mechanism, geology and local soil conditions. This paper reports the outcome of the one-dimensional nonlinear ground response analysis (GRA) conducted for a typical site of Amingaon, Guwahati, using scaled strong motions of various intensities. Soil profiles at the study regio...

Foundation, the key element of every structure, is a composite system comprising of structural footing and soil within the 'significant depth of load transfer'. In general , a shallow foundation is preferred unless the structure and the ground demand for deep foundation. With the recent advancements in the reinforced soil technologies, the reinforc...

Seismic design of any structures requires the dynamic characteristics (modulus degradation and damping variation) of underlying soil in order to incorporate the soil structure interaction effects, and such dynamic behavior is different for different soils. But, due to unavailability of the site-specific or region-specific dynamic soil properties, g...

To evaluate the importance of small-strain shear modulus in geotechnical engineering applications, different techniques such as bender element, resonant column apparatus and on-sample LVDTs are being used by the researchers. This paper presents the results obtained from resonant column tests, bender element tests and on-sample LVDT for sandy soil,...

This paper highlights the importance of the measurement of local strains in triaxial test using on-sample transducers. Specimens of sandy soil, prepared at two different relative densities (30% and 90%), were subjected to different effective confining stresses, and sheared monotonically as well as cyclically. Local strain measurements are obtained...

This chapter provides an understanding of the performance of the geocell-reinforced sand foundations having clay subgrades of varying strengths. Model tests were conducted on a rigid circular model footing of 150 mm diameter (D) resting on foundation beds of different configurations prepared in a steel tank having dimensions of 1 m × 1 m × 1 m. Dif...

The stress–strain characteristics of soil under monotonic loading conditions and the dynamic properties of soils under cyclic loading are necessary for foundation engineering, ground response analysis and soil structure interaction studies. In the absence of site/region-specific properties, it is a common practice to use representative parameters b...

This chapter presents the seismic vulnerability of Kathmandu City (Nepal), based on Nepal 2015 earthquake, in terms of the ground response and liquefaction potential. The spatially well-distributed 10-boreholes and ground motions of Mw 7.8 Nepal 2015 earthquake recorded at five different stations were adopted for the analysis. The range of peak gro...

Soils subjected to earthquake motions undergo random variations in stress, strain and frequency during the entire period of shaking. The spatial and temporal complexity of the strong motions is commonly addressed through simplistic strain-controlled or stress-controlled cyclic loading tests as a part of laboratory investigations. Such a methodology...

The response of saturated soil during earthquakes is governed by many factors such as frequency content, strain, stress, excess pore-water pressure and strength variations within the soil mass. This paper highlights the effect of strains on the stiffness modulus and its degradation at the liquefied condition of cohesionless soil. Cyclic triaxial (C...

Topographic input parameters such as slope, curvature, and drainage area are derived from a Digital Elevation Model (DEM) representing the spatial elevation, and are widely used as important sources of geospatial information. Based on the chosen DEM and its derived paramters, physically based GIS models, such as TRIGRS, can compute the transient de...

Landslides constitute a major hydrogeological hazard component of the natural disasters that affect most of the hilly regions around the globe. The impact of rainwater infiltration in causing landslides is widely recognized. A landslide study has a two-way approach; local scale (slope stability analysis) and regional scale (landslide susceptibility...

This volume presents recent advances and developments taking place in geotechnical aspects of natural disaster mitigation and management. The chapters of this book are based on the invited lectures delivered by eminent researchers at the Third Indo-Japan Workshop on Geotechnics for Natural Disaster Mitigation and Management. This book will be a use...

Seismic design of any structures require the dynamic characteristics (modulus degradation and damping variation) of underlying soil in order to incorporate the soil structure interaction effects, and such dynamic behaviour is different for different soils. But, due to unavailability of the site-specific or region-specific dynamic soil properties, g...

This paper presents the dynamic response of retaining wall models backfilled with different types of sand–tyre chips (STC) mixtures using shaking table tests. The STC mixtures with different tyre chips proportions, such as STC10, STC20, STC30, STC40, STC50 and STC0 (control test) were considered as backfill materials. A 600 mm retaining wall that i...

This paper presents the stability analyses of non-homogeneous slopes under different loading conditions. A non-homogeneous soil slope with two different soil layers is considered. Special cases are created, varying the height of the layers, to account for the non-homogeneity of the earth slope. A water table is considered in this study to account f...

This article presents a comprehensive study of dynamic soil properties [namely, initial shear modulus-Gmax; normalized shear modulus reduction (G/Gmax); and damping ratio (D) variation curves] and pore water pressure parameters of a river bed sand (Brahmaputra sand), sampled from a highly active seismic region (northeast India). Two independent hig...

This article proposes solutions for stiffness estimation of Double-D shaped caisson foundations embedded in three different types of ground profiles (stiffness variation along the depth: homogeneous, linear and parabolic). The approach is based on three dimensional finite element analyses and is in line with the methodology adopted in Eurocode 8-Pa...

The most devastating factor for slope failures is rainfall infiltration. Surficial slope failures in residual soil slopes are a common sight. In general, slope angles vary considerably from being flat to steep in natural conditions, which govern the hydrological regime of the slope. Further, different types of soils behave differently under rainfal...

Seismic analysis of structures will not be complete without a proper investigation of underlying soil behavior to dynamic loading. Such dynamic behavior is complex in nature due to many influencing parameters. The complex dynamic soil behavior can be represented using the strength and stiffness properties such as low-strain shear modulus (Gmax), mo...

This paper presents the results of shaking table tests on retaining wall models using recycled tire chips as compressible inclusions. Scrap tire derived tire chips of 10 × 10 mm size and about 20 mm length have been used in the study. The 600-mm-height model wall is constructed in a Perspex container and instrumented with pressure sensors and LVDTs...

Reinforced soil walls are being extensively used in various infrastructure projects. In the view of increasing seismic events, efficient seismic performance of these important public infrastructure facilities must be ensured. Seismic analysis of reinforced soil walls is an active research area for the geotechnical community which aids in effective...

Foundation stiffness plays a crucial role in the stability analysis of structures to incorporate the Soil Structure Interaction (SSI) effects. Current design approaches of estimating foundation stiffness include advanced dynamic finite element, distributed spring approach, and lumped spring approach. The aim of this paper is to overview the differe...

Irregular stress waves generated during an earthquake induce irregular shear stresses in the soil, which affect the dynamic behaviour of soil significantly. Laboratory investigations on the response of soils during real earthquake scenario are very limited. This paper reports about the response of saturated sandy soils subjected to irregular cyclic...

Conventional triaxial tests mostly use external LVDTs attached to the actuator of automated triaxial system so as to measure the strain. However, these LVDTs measure the external strain applied and not the strain developed in the sample during shearing. This paper presents the use of on-sample transducer to measure localized strain in a soil sample...

Hillslopes within the city of Guwahati consist of geological stratification that characterize progressive stages of residual weathering, which can be categorized as basal rock, decomposed granitic rock and corestones, saprolitic and lateritic residual overburden. Saprolite formation is the layer of residual soil derived from isovolumetric weatherin...

Liquefaction is considered as a major crucial hazard among different seismic risks. Ground improvement methods commonly employed, to improve the natural site conditions under such situations, lead to better performance of various engineering structures built up on. The paper presents various aspects of liquefaction hazard mitigation of loose satura...

Pile foundations in liquefiable soils need to be checked for the bending moments due to the liquefaction induced stresses to arrest the plastic hinge formation. Recent studies reveal that the bending moments in the pile are significantly higher during the partial liquefaction stage (excess pore water pressure ratio <1.0) than at the fully liquefied...

Stability of rock slope along the stretch of Badrinath National Highway (NH-58) of Garhwal Himalayas in Uttarakhand, India is very much essential to protect the infrastructure and livelihood in the area nearby. Every year this part of the slope has been facing severe landslides due to intensive rainfall causing substantial damages. The chosen area...

Estimation of strain-dependent dynamic soil properties, e.g. the shear modulus and damping ratio, along with the liquefaction potential parameters, is extremely important for the assessment and analysis of almost all geotechnical problems involving dynamic loading. This paper presents the dynamic properties and liquefaction behaviour of cohesive so...

Natural slopes are non-homogeneous in nature, which behave differently than homogeneous slopes. The non-homogeneity in slopes exist in various ways, which include change in stratifications and/or shear strength parameters (cohesion, friction angle) with depth, presence of saturated–unsaturated zones, etc. This study is performed to show the effect...

This contributed volume encompasses contributions by eminent researchers in the field of geotechnical engineering. The chapters of this book are based on the keynote and sub-theme lectures delivered at the Indian Geotechnical Conference 2017. The book provides a comprehensive overview of the current state-of-the-art research and practices in differ...

Liquefaction is considered as a major hazard among different seismic risks. Ground improvement methods are commonly adopted to improve the liquefiable sites. The paper presents various aspects of liquefaction mitigation strategies to be implemented for liquefaction susceptible sites with focus on granular inclusions. A short discussion on liquefact...

Discontinuities in the form of joints, bedding planes and faults create anisotropy in the rock mass. Discontinuities are the weakest zones in the rock mass. The slope stability analysis of rock masses has been a challenging task due to the presence of discontinuities in various forms which result in different types of slope failures. Failure mechan...

This article highlights the implication of site-specific properties on seismic ground response studies. One-dimensional equivalent linear ground response analysis was carried out using site-specific dynamic properties of locally available soils of Guwahati city, and the results are compared with those obtained using existing strain-dependent dynami...

The stability analysis of rock slopes has been a challenging task because of the presence of discontinuities in various forms which result in different types of slope failures. Discontinuities are the weakest zone in the rock mass. Failure mechanism of rock slope mainly depends on the characteristics of discontinuities. Discontinuities in the form...

Limit equilibrium method for slope stability analysis relies on Factor of Safety for defining the (in)stability condition of a given slope. As such this method fails to describe the evolutionary process, and the path it follows leading ultimately to failure. Thus the question remains: why landslide occurs when FoS > 1.0 and how a slope remains stab...

Strain-controlled cyclic triaxial tests were conducted at different shear strain amplitude, relative density and confining pressure ranging from 0.015-4.5%, 30-90% and 50-150 kPa, respectively, with loading frequency of 1 Hz. During experimental investigations at these high cyclic strains the hysteresis loops was observed to be asymmetrical. In suc...

Landslides constitute a major hydro-geological hazard and form a significant component of the natural disasters that affect most of the hilly regions round the globe. The impact of rainwater infiltration in causing landslides is widely recognized. A landslide study has a two way approach; local scale (slope stability analysis) and regional scale (l...

The applications of scrap tire-derived recycled materials in civil engineering applications have been increasing largely because of their potential economic and environmental benefits. This paper first evaluates sand–tire chip (STC) mixture properties and then discusses about the application of STC mixtures in geoengineering applications through la...

This article reports a laboratory model investigation performed on circular footing rested on geocell-geogrid reinforced foundations of different configurations. Model foundations were comprised of geocell-sand mattress (with an additional planer geogrid at bottom) of varying thicknesses (H = 0.63 to 2.19D; where, D = footing diameter) placed on cl...

Geocell-reinforcement in ground improvement is being used very extensively in present days. It is a three dimensional honeycombed confinement system, made of geosynthetics, which significantly improves the bearing capacity of soft soils, specially, in foundations, and pavements applications. Apart from improving the soil strength, it has also been...

Stiffness and damping properties of soil are essential parameters for any dynamic soil structure interaction analysis. Often the required stiffness and damping properties are obtained from the empirical curves. This paper presents the stiffness and damping properties of two naturally occurring sandy soils collected from a river bed in a highly acti...

Use of scrap tire derived (STD) geomaterials in geotechnical engineering applications has received growing interest to prevent creation of wastes and conserve natural resources towards achieving sustainability. STD geomaterials and their mixtures with soils are being used in highway embankments, retaining walls, landfills and other applications as...

Behaviors of sandy soils under dry and saturated conditions significantly differ from each other, especially under cyclic loading conditions. This paper highlights the behavior of dry and saturated Brahmaputra sand (DBS and SBS) subjected to constant strain monotonic and cyclic triaxial tests. Monotonic tests were conducted on specimens prepared at...

Dynamic loading conditions, such as earthquakes, may result in the generation of high shear strain (>5%) in the soil. Conventionally, dynamic properties of soils are estimated from the tests conducted up to a shear strain of 1% by considering Symmetrical Hysteresis Loop (SHL). However, it is commonly observed that the hysteresis loops become progre...

Many major river bridges were constructed in highly active seismic areas of India much before the seismic code development. Bridges are lifelines infrastructure and as a result, it is necessary to requalify/reasses these structures in the light of the new and improved understanding of seismic resistant design philosophies. The aim of the paper is t...

This paper investigates the performance of retaining wall models using recycled tyre chips as compressible inclusions under dynamic loading through shaking table tests. Scrap tyre derived tyre chips of 10 × 10 mm size and about 20 mm length have been used in this study. The 600 mm high model wall is constructed in a poly(methyl methacrylate) (PMMA)...

Proper management of waste tires is a major problem in many regions of the world. Scrapped tires in different forms are being used in various civil engineering applications. This paper presents the feasibility study on the use of recycled tire chips mixed with sand as lightweight backfill material for retaining wall applications. Properties of sand...

The ever increasing infrastructure development requires adequate and competent ground, which is becoming scarce at present. Thus, developing techniques for improving the weak soil (having low bearing capacity and/or likely to undergo excessive settlement) into a competent acceptable condition is a major task for geotechnical engineering practice. I...

Dynamic loading conditions, such as earthquakes, may result in the generation of high shear strain (> 5%) in the soil. Conventionally, dynamic properties of soils are estimated from the tests conducted up to a shear strain of 1% by considering Symmetrical Hysteresis Loop (SHL). However, it is commonly observed that the hysteresis loops become progr...

A series of laboratory model tests was performed on rigid circular footing, 150 mm in diameter (D), resting on surfaces of different layered foundations. The experimental programme considered different foundation configurations by varying the thicknesses (H) of dense sand layers, in the range of 0.63–2.19D, overlying clay subgrades of different str...

Rock slides and rock falls are always the recurrent features in highways running along hill slopes. Rock falls are mainly caused due to the disorientation of joints which are triggered during heavy rainfall and seismic events leading to falling of rock blocks from the crown portion of the slope. Severe damage to life and property as well as disrupt...

Rockslides and rock falls are a common phenomenon observed along transportation corridors running along hill slopes bringing the communication through these networks to a standstill. Restoration of traffic consumes considerable amount of money and time causing inconvenience to commuters. A huge amount of loss to lives and property is caused due to...

This paper presents numerical analysis of a reinforced soil retaining wall under static and dynamic loading. Finite difference programme, FLAC, was used to analyze behaviour of the reinforced soil retaining wall. In the analysis, behavior of soil–wall interaction, soil-reinforcement interaction has been considered. Analyses were conducted using dif...

Stability of rock slope along the stretch of Badrinath National Highway (NH-58) of Garhwal Himalayas in Uttarakhand, India is very much essential to protect the infrastructure and livelihood in the area nearby. Every year this part of the slope has been facing severe landslides due to intensive rainfall causing substantial damages. The chosen area...

Conventional triaxial tests mostly use external LVDTs attached to the actuator of automated triaxial system so as to measure the strain. However, these LVDTs measure the external strain applied and not the strain developed in the sample during shearing. This paper presents the use of on-sample transducer to measure localized strain in a soil sample...

Hill slopes within the city of Guwahati consist of geological stratification, that characterize progressive stages of residual weathering, which can be categorized as basal rock, decomposed granitic rock and corestones, saprolitic and lateritic residual overburden. Saprolite formation is the layer of residual soil derived from isovolumetric weather...

Analysis and design of machine foundations is very important area of research and has always been a topic of special attention in foundation engineering. The design of machine foundation majorly depends on the dynamic properties of soils. Investing dynamics properties is therefore very sensitive and challenging task. This demads complex mathematica...

Shear wave velocity is a direct indicator of stiffness of an isotropic medium which is frequently used to represent subsurface stratification. Non-invasive seismic survey like Multichannel Analysis of Surface Waves (MASW), in both active and passive forms, is widely used in professional practice due to its rapid implementation. Various stages in an...

Soil–geosynthetic interaction parameters and their determination play a vital role in the design of reinforced soil structures. Direct shear test and/or pullout test are commonly used to determine the interaction parameters. Often, it is economically viable to obtain these parameters through existing test setups that are conventionally used in geot...

A study of the seismic behavior of rigid-faced reinforced soil-retaining walls subjected to scaled earthquake ground motions is presented in this paper. A numerical model was developed and validated to simulate the shaking-table test of a rigid-faced reinforced soil-retaining wall. The calibrated numerical model was extended to develop a full-scale...

In this paper, influence of different types of soils and geosynthetics on soil/geosynthetics interface behaviouris investigated by direct shear and pullout tests. Three different types of cohesionless soils and three different types of geosynthetics materials are adopted for experimental investigation. A series of large direct shear tests and pullo...

This paper presents forensic investigations of earthquake induced failures during Sikkim 2011 Earthquake, India. Detailed field geotechnical observations and geophysical investigations have been carried out at selected locations affected by 2011 Sikkim earthquake. Field observation, drilling of boreholes with sample collection (DBS), surface wave t...

This paper focuses on the numerical analysis of reinforced soil retaining walls using finite difference programme, FLAC. In the analysis, behaviour of soil-wall interaction, soil-reinforcement interaction has been considered. Dynamic loadings were applied in the form of sinusoidal waves at the base of the foundation soil. Analyses were conducted us...

A series of laboratory model tests was performed to investigate the behavior of geosynthetic reinforced stiff clay foundation systems under circular loading. The footing consisted of a rigid circular steel plate with a diameter of 150 mm. Five different series of tests were performed in both homogeneous (clay or sand) and layered configurations. Th...

Stress-controlled cyclic triaxial tests were conducted on reconstituted specimens prepared at 61% relative density. The samples were subjected to cyclic stress ratios (CSR) in the range of 0.1-0.4 at a loading frequency 1 Hz and confining pressure 100 kPa. Results of experimental investigation are reported in terms of the effect of CSR and cyclic s...