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Microbially induced calcite precipitation method is gaining attention as an environmentally friendly method for enhancing the strength and liquefaction resistance of sands as compared to conventional techniques, which are carbon-intensive and cement-based. However, the durability and effect of weathering on liquefaction resistance of biocemented sand are not yet fully explored. Thus, the present study was aimed at investigating the durability of biocemented sand by subjecting the biotreated sand to different weathering conditions, i.e., variable time periods of aging (1.5, 3, 4.5, and 6 months), cyclic freeze–thaw (5, 10, 15, and 20 cycles) actions, and wet–dry (5, 10, 15, and 20) cycles. The biocemented sand biotreated using Bacillus (B.) Sphaericus was tested for ultrasonic pulse velocity (UPV) and unconfined compressive strength to assess durability under different tested conditions. The amount of calcite precipitation was determined, and microstructural changes were also observed through SEM and EDX methods. The liquefaction resistance of biocemented sand was investigated using UPV results and dynamic cyclic simple shear test results. Overall, the results showed up to 2.8 times increase in strength after 6 months of aging, and significant strength with liquefaction resistance was maintained even after 20 freeze–thaw and wetting–drying cycles.

In Garhwal Himalayan region, seismicity plays a major role in inducing mass movement. Especially at places where active faulting occurs, multiple and retrogressive slope failures have been observed. The active tectonism of the Himalayan collision zone makes the whole mountain chain fragile and instable. In this context, an endeavor has been made in the present study to correlate the impact of Main Boundary Thrust (MBT) on the overall landslide susceptibility for a 74-km stretch of NH 7 in the Garhwal Himalaya, using statistical models of landslide susceptibility zonation (LSZ) mapping. The results of the study show that slope angle, road network and distance from MBT are the most crucial landslide causative parameters in the study area, with statistical contribution of 26%, 20% and 18%, respectively. The study also produces an accurate LSZ map for this stretch of NH 7, which shows that almost 30% of the area has high to very high degree of landslide susceptibility. The prepared LSZ map will be of practical significance for institutionalizing any future landslide mitigation programs in the study area.

Catastrophic landslides and associated destructions are increasing every year, because of the change in climatic conditions and land-use patterns. The ecologically sensitive zones of Western Ghats are highly susceptible to landslides and require scientific attention in developing an efficient early warning system. Definition of empirical rainfall thresholds on local, regional or global scales is the most commonly followed method of forecasting rainfall induced landslides. The limitations associated with such thresholds demands for better forecasting performance, incorporating the effect of physical processes in the initiation of landslides. This study is an attempt to forecast landslides in Idukki district, using mobility functions. The function separates the impossible and certain mobilisation parts and forecasts whether landslides can occur or not. Based on the critical value of mobility function, two different warning levels are proposed for four different reference areas in the district. The study shows that the model is 97% efficient in smaller areas with uniform topographical and geological conditions, and the performance is reduced as the area becomes larger, with varying topographical and geological properties. The model proves to be an effective landslide forecasting tool that can be integrated with a rainfall forecasting system, to develop an early warning system for the region.

Structures constructed on expansive soils are experiencing higher upward pressure due to swelling- shrinkage nature of expansive soil. India has 15–20% expansive soil, which causes severe damage to the existing structure, including pavements, dams, multi-storey buildings, retaining walls. The aim of the study is to suitably reduce the distressed caused by the expansive soil on paved structures. The experimental result of expansive soil subgrade reinforced with and without coir geotextile mat has been presented in this paper. Lime and silica fume, treated and untreated coir geotextile mat with polypropylene fiber net has been used. A single and double layer of coir geotextile mat at various depths have been placed to evaluate the effect of reinforcement on expansive soil subgrade. The treatment was carried out to enhance the efficiency of coir geotextile for reducing the swelling pressure of the expansive soil subgrade. The chemical and microstructural components of expansive soil samples were investigated by using X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR). The constant volume swelling pressure, California Bearing Ratio (CBR) and large size direct shear (300 mm × 300 mm × 150 mm) tests have been carried out to evaluate the effect of treated and untreated coir geotextile on expansive soil subgrade. The experimental results analyzed indicates that the lime treated coir geotextile mat reduces the upward swelling pressure by 52.19% in single-layer and 81.89% in double-layer. The tangible improvement in the shear strength and bearing capacity of expansive soil subgrade was observed with the inclusion of lime treat coir geotextile. A lime treated coir geotextile in a single or double-layer can be used to stabilize the expansive soil subgrade. The improved property of reinforced expansive soil subgrade can reduce the thickness of the subbase and base course layer in paved structure.

Debris flows account for a substantial economy and property loss in Western Ghats of Kerala, India, especially during monsoon seasons. Wayanad district is an active erosion zone in the plateau margins of Western Ghats, and there is a remarkable rise in the number of debris flows since 2018, due to very high-intensity rainfalls in this region. This study comprises geotechnical investigation, runout modeling, and calibration of friction parameters of Kurichermala debris flow, one of the devastating debris flow events that happened in Wayanad, during the 2018 monsoon. The detailed investigation and back analysis of such events are substantial in calibrating the flow parameters for the region. These parameters can be used for predicting the flow paths of possible debris flows and quantitative risk assessment in the future. The geotechnical investigation provided vital information regarding the soil type and shear strength parameters of the debris flow and has helped in understanding the flow behavior. A dynamic numerical model, rapid mass movements (RAMMS), was used for the back analysis of the debris flow, using the shape information of the flow. For precise calibration using statistical comparison, an image processing tool has been developed, to compare the structural similarity of simulated results with the original shape of debris flow. The dry-Coulomb friction coefficient (μ) was calibrated as 0.01 and turbulent friction coefficient (ξ) as 100 m/s2 for the event, using Voellmy-Salm rheology. The shape predicted by the model had a similarity index of 0.626 with the actual shape of debris flow. The results were found to be in accordance with the field and geotechnical observations. Hence, the results can be used to predict the shape of possible debris flows in the study area. The study is the first of its kind for the region and has significant influence in risk assessment for this highly susceptible landslide zone.

Pavement structures constructed on the expansive soil subgrade experience a higher upward pressure compared to any other subgrade material. The upward pressure is caused due to high swelling and shrinkage characteristics of expansive clay soil. The present study has investigated and identified the mechanisms by which a remolded expansive soil can be modified to reduce the upward pressure and swelling (heave). To achieve this, a lightweight, environmentally friendly, and high pressure resistive expanded polystyrene (EPS) granules have been used with expansive soil s from three different locations of Madhya Pradesh state, India. The study has been performed to understand the swelling and strength characteristics of soil with and without the use of EPS (density = 21.6 kg/m3) as per ASTM specifications. The chemical and microstructural components of the expansive soil were investigated using autotuned total reflectance Fourier transform infrared (ATR-FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). Several laboratory experiments, including optimum moisture content, maximum dry unit weight, grain-size distribution, liquid limit, plastic limit, shrinkage limit, free swell index, unconfined compressive strength, and pressure swelling tests were carried out on the statically compacted expansive clay soil specimen with and without EPS (0.25%, 0.50%, 1.00%). The maximum addition of EPS was considered as 1% as the very high expansion was observed, and beyond this, further addition of EPS was not feasible. The results show that the swelling pressure, expansion percentage, and time rate of swell decrease, whereas the unconfined compressive strength (UCS) increases with the addition of EPS. The inclusion of EPS in expansive clay soil exponentially reduced the heave and the upward pressure, whereas the maximum UCS was observed at 0.5%.

Structures constructed on expansive soils experience higher upward pressure due to their swelling characteristics. Various conventional treatment methods developed to counteract swell–shrin...

The rapid development of infrastructure often encounters the loose soil subgrade and is becoming difficult to carry to construction activities. Various mechanical and chemical methods have been developed to reduce the impact of the expansive soil. Mechanical stabilization of expansive soils by reinforcing with polypropylene fibers and geogrid is one of the sustainable solutions. Geogrids and polypropylene fibers have been extensively used to reinforce the expansive soil subgrade and foundations as individuals. The polypropylene fiber reinforcement enhanced the tensile strength capacity of the reinforced expansive soil wherein the geogrid reinforcement is the quick fix mechanical stabilization technique, which reduces pavement failures. In this research, the combined effect of the polypropylene fiber and geogrid reinforcement has been evaluated to stabilize the pavement subgrades. Various mechanical strength tests such as unconfined compressive strength (UCS) and large direct shear box tests were conducted to evaluate the mechanical interaction between expansive soil subgrade, polypropylene fiber, triaxial geogrid, and biaxial geogrid at the interface. Polypropylene fiber of 12-mm length was used in the proportion of 0.25, 0.5, and 1.0% and single share geogrid layer at mid-depth. The result shows that the shear strength of reinforced subgrades with a layer of biaxial/triaxial geogrid and polypropylene fiber increases significantly. It is also observed that the unconfined compressive strength of the expansive soil increased with the inclusion of polypropylene fiber and geogrid. The combined reinforcement method shows an effective treatment methodology to improve the engineering property of expansive soil subgrades.

In lieu of the conventional carbon-intensive and expensive cement-based ground improvement methods, microbially induced calcite precipitation (MICP) method has gained prominence recently as a susta...

This study explored the effect of indigenous bacteria present in the soil to stabilized swelling behavior and improving the mechanical property of expansive soil. The objective of the research is to investigate the effectiveness of the biostimulation microbial induced calcite precipitation (MICP) for controlling the swelling-shrinkage behavior and improving shear strength of expansive soil. An attempt was made to develop an effective procedure to culture the indigenous bacteria for treating clays with varying plasticity and improve their engineering behavior. The detailed procedure has been investigated to effectively apply the MICP technique in clay soil, considering its low permeable nature. The applicability of biostimulation to clayey soils in minimizing their swelling potential and improving the strength is assessed. Both macroscale and microscale studies were conducted on untreated and biostimulated soils to observe changes in plasticity, strength, swelling, mineralogical, chemical characteristics. The present method has shown an effective alternative to improve the road pavement subgrade without affecting the eco-system of natural soil. The method investigated the effective way of providing the enrichment and cementation solution in clayey soil, which is the major concern in current literature. The study confirms that the calcite content has been increased with biostimulated MICP treatment up to 205% in the treated specimens and which future increased the unconfined compressive strength and split tensile strength. A reduction in the swelling pressure and swell strain is also observed. The results show that a cost-effect and eco-friendly method can be deployed for stabilizing the road pavement subgrades. The statistical assessment using multivariate analysis and hierarchical clustering dendrogram has been carried out to investigate the effect of the MICP treatment protocol on different soil and engineering parameters.

Earthquake-induced liquefaction causes soil to exhibit fluidlike behavior due to a sudden increase in pore water pressure and a concurrent decrease in effective stress. The liquefaction ca...

Structures constructed on expansive soils are experiencing a higher upward pressure due to swelling–shrinkage nature of expansive soil. India is having 15–20% land with expansive soil and causes severe damages to the existing structure like pavement, dams, multi-story building, retaining wall, etc. This study investigated and identified the mechanisms by which swelling pressure can be mitigated in expansive clay soil. The single layer of coir geotextile is used with the treatment of lime and silica fume. The coir treatment is made to enhance the efficiency of coir geotextile to reduce the swelling pressure of expansive soil subgrade. Chemical and microstructural component of expansive soil sample is investigated by using X-ray diffraction (XRD), scanning electron microscope (SEM) and Fourier transform infrared (FTIR). The constant volume swell pressure test with and without treatment of coir geotextile mat has been carried out. The experimental result analyzed which indicates that the lime-treated coir geotextile mat significantly reduces the upward swell pressure and heave of expansive soil subgrade.

Microbially induced calcite precipitation (MICP) is a recently developed technique for microbiological ground improvement that has been applied for mitigating various geotechnical challenges. However, the major challenges, such as calcite precipitation uniformity, presence of different bacteria, cementation solution optimization for cost reduction, and implementation under non-sterile and uncontrolled field environment are still not fully explored and require detailed investigation before field application. This study aims to address these challenges of MICP to improve the geotechnical properties of sandy soils. Several series of experiments were conducted using poorly graded Narmada River (India) sand, which were subjected to various biotreatment schemes and tested for unconfined compressive strength (UCS), split tensile strength (STS), ultrasonic pulse velocity (UPV), hydraulic conductivity (after 6 d, 12 d, and 18 d of treatment), and calcite content. The microstructure of sand was examined through a scanning electron microscope (SEM). Initially, the sand was individually augmented with two non-pathogenic bacterial strains, i.e. Sporosarcina (S.) pasteurii and Bacillus (B.) sphaericus. The stopped-flow injection method was adopted to provide cementation solutions at three different durations (treatment cycle) of 12 h, 24 h, and 48 h and three different pore volumes (PVs) of 1, 0.75, and 0.5. The pore volume here refers to the porosity which is expressed as a ratio, i.e. a porosity of 50% was used as 0.5. The results showed rock-like behaviors of biocemented sand with the UCS, STS, and UPV enhancement up to 2333 kPa, 437 kPa, and 2670 m/s, respectively. The hydraulic conductivity reduction of 96.6% was achieved by 12% of calcite formation after 18 d of treatment using Sporosarcina pasteurii, 12-h treatment cycle, and one pore volume of cementation media in each cycle. Overall, a 24-h treatment cycle and 0.5-pore volume cementation solution were found to be the optimal treatment which was effective and economical to achieve heavily cemented, rock-type biocemented sand using both bacteria.

The northern part of INDIA is most vulnerable in failure of slopes due to hill region with complex geology, high-intensity rainfall and frequently occurrence of earthquakes. The stability of slopes has traditionally analyzed using deterministic methods. But uncertainty plays major role in geotechnical engineering. the probabilistic characterization of uncertainties in input variables for the assessment of slope stability is very helpful. In this paper, the safety of slope using deterministic and probabilistic methods under static and pseudo-static loads is carried for Lungchok landslide which is in south district of Sikkim state, India. The Factor of safety calculated by deterministic cannot represent the stability of slope exactly as it is limited to the single value of parameters. The stability of slope is independent of single soil parameter but dependent on random process with distribution of soil parameters. Rather than the conventional factor of safety against the sliding failure the probability of sliding failure is most useful. The stability of slope is analyzed using two approaches deterministic and probabilistic analysis under the effects of static and pseudo static forces. The deterministic approach with Morgenstern Price limit equilibrium method and the probabilistic approach with Monte Carlo simulation have been performed for the stability analysis of Lungchok landslide using Geo-Studio Software. The dependence and efficiency of the probabilistic strategies in the investigation of slope stability was highlighted in this paper.

Tunnels are the most important infrastructure components as it plays a major role in public infrastructure, water transport and the production of hydroelectric power. The constant variation in the geological conditions affects the tunnel stability which can be achieved using flexible rock support methods. The analysis and understanding of the prevalent complex rock mass in a region which is highly seismically active is a challenge and necessary for the successful execution of any tunnelling project. Therefore, a pseudo-static approach has been studied to understand the impact of earthquakes on circular tunnels using the Phase 2 software. The rock mass surrounding the tunnel is modeled using the continuum approach and continuum with interface approach where joints were incorporated in the model as an interface. For this study, a tunnel model with specification (diameter-6 m, depth-100 m) with a Q range of 1–30 was used to examine the impact of rock mass quality. The study revealed that while the seismic load remains unchanged, the magnitude of the axial force on the liner and the net increase due to seismic loading referred to as seismic axial force, increase as the rock mass quality decreases. The diameter of the circular tunnel at a depth of 100 m is increased from 6 to 24 m at an interval of 6 m to check the influence of the tunnel diameter under the seismic loading. It was observed that the seismic axial force decreases with the tunnel diameter for the rock mass Q = 1 (“very low” rock class) and strong rock, it is comparatively small.

Seismic damage surveys and analyses conducted on modes of failure of structures during past earthquakes observed that the asymmetrical buildings show the most vulnerable effect throughout the course of failures (Wegner et al., 2009). Thus, all asymmetrical buildings significantly fails during the shaking events and it is really needed to focus on the accurate analysis of the building, including all possible accuracy in the analysis. Apart from superstructure geometry, the soil behavior during earthquake shaking plays a pivotal role in the building collapse (Chopra, 2012). Fixed base analysis where the soil is considered to be infinitely rigid cannot simulate the actual scenario of wave propagation during earthquakes and wave transfer mechanism in the superstructure (Wolf, 1985). This can be well explained in the soil structure interaction analysis, where the ground movement and structural movement can be considered with the equal rigor. In the present study the object oriented program has been developed in C++ to model the SSI system using the finite element methodology. In this attempt the seismic soil structure interaction analysis has been carried out for T, L and C types piled raft supported buildings in the recent 25th April 2015 Nepal earthquake (M = 7.8). The soil properties have been considered with the appropriate soil data from the Katmandu valley region. The effect of asymmetry of the building on the responses of the superstructure is compared with the author’s research work. It has been studied/observed that the shape or geometry of the superstructure governs the response of the superstructure subjected to the same earthquake load.

Globally 30% of landslides occur in the northeastern part of India [1]. One of the major earthquake events in Sikkim, India occurred on 18th September 2011 (Mw 6.9) led to over 300 landslides and 122 human deaths [2]. These landslides not only controlled by natural disasters but initiated due to human activities. The present study considered Lungchok landslide occurred in south district of Sikkim due to 2011 seismic event. The study focused on the failure mechanism of the landslide based on finite element analysis by adopting eight different cases. The deformation characteristic was investigated for dry and saturated slope conditions under static and dynamic behavior considering vehicle loads using GeoStudio software. The FEM analysis has been carried out using load deformation and linear elastic. The analysis shows that the failure of the slope was not sudden due to the 2011 earthquake event, but progressive failure was observed with time and construction activity. The paper demonstrates that, an increase in infrastructure development including construction by hill cutting increased the initiation of landslide with soil erosion. The cracks developed after 2011 earthquake event led to further deformations during future disasters required effective stabilization measures.

Safety against earthquake hazards can be achieved by considering site safety against geotechnical problems and structural safety against dynamic forces. Geotechnical problems such as amplification, landsliding and soil liquefaction are dangerous in regard to the scale of damage. Assessment of risk against such problems is a part of seismic microzonation process. Seismic risk is highly affected by risk factors due to geological environment and geotechnical properties of soils. In this study, it is attempted to identify and develop hazard maps against seismic hazard for Vijayawada city, India, where the subsoil consists of thick alluvial formations along the river. In particular, the study aims at the evaluation of site effects using the available geotechnical data and carrying out microtremor testing in the study area. The geotechnical zonation of the subsoil of the city suggests a high vulnerability of the physical environment in addition to site amplification of the ground motion phenomena. The ground response analysis at the surface was conducted by 1D equivalent linear method and by microtremor testing. From the ground response analysis, peak acceleration, frequency and amplification parameters were assessed and the city was divided into different zones corresponding to each value. Liquefaction hazard was quantified using SPT-based method in combination with the dynamic analysis. These findings supply an indispensible tool for the seismic retrofitting of the buildings and for the mitigation of the seismic risk for small to medium earthquakes in the city.

Liquefaction is a complex phenomenon where the soil is subjected to high strain levels due to dynamic loading at the time of seismic events, contributing to severe damage and collapse of the structures. The effect of liquefaction can be predicted in three stages, i.e., evaluation of susceptibility, hazard and deformations. Soil susceptibility to liquefaction can be assessed using the geotechnical properties such as grain size, age of the soil deposit, penetration resistance of the soil, whereas hazard can be assessed in terms of factor of safety estimated against liquefaction. In the present study, one-dimensional equivalent linear ground response analysis has been carried in the study area Vishakhapatnam, Andhra Pradesh (India) and the surface peak ground acceleration (PGA) has been estimated using DEEPSOIL. The surface PGA values obtained have been used in liquefaction hazard assessment using stress-based method (SBM) and energy-based method (EBM). Hazard maps were generated from the estimated values of PGA and factor of safety against liquefaction (F L). The surface PGA values obtained are in the range of 0.09–0.14 g which are higher than 0.1 g (limiting value provided by Seismic code of India (IS: 1893-2002)). It is observed that the locations in the central part of the city are prone to higher accelerations comparatively. From liquefaction potential assessment, it is evident that most of the locations in northern and central parts of the city are prone to liquefaction. As the study area has two operational ports and is highly industrialized, findings from the present study will be helpful in retrofitting, analysis and design of structures, therefore, solving practical challenges in structural and geotechnical engineering.

The seismic behavior of a saturated soil depends on the potential for significant strains or strength loss that can contribute to ground deformations or instability during an earthquake. Historic large earthquakes throughout the world explain that the liquefaction related ground failure commonly causes extensive structural and lifeline damage in urban areas. Detailed assessment of liquefaction hazard is important for evaluating and reducing the risk through appropriate mitigation techniques. Soil liquefaction generally occurs in areas underlain by low density, saturated granular sediments. The liquefaction susceptibility can be mapped using specific, well established geologic and geotechnical criteria. Damages caused by liquefaction of saturated soil revealed that after liquefaction the ground failed, sand boiling occurred and the structure subsided unevenly causing tilting, cracking or even collapse. After the devastating 2001 Gujarat earthquake, the Government of India has paid serious attention to carry out the detailed site characterization and ground response studies which are very crucial in seismic microzonation and it is also accepted as a guiding tool in land use planning and safe construction practices to avoid the loss from the future earthquakes. Very preliminary process of reducing the effects of earthquake is by assessing the hazard itself. As part of the national level microzonation program, Department of Science and Technology, Govt. of India has initiated microzonation of 63 cities in India. In this research paper two urban centers Delhi and Vijayawada city which falls in seismic zones IV and III respectively are considered for liquefaction hazard assessment. Since these two cities are falling in the areas with high and moderate seismic probability, there is a great need for the assessment of liquefaction potential. An attempt has been made estimate the liquefaction hazard for these two cities considered using the measured shear wave velocities and SPT borehole data. From the detailed liquefaction assessment, it is observed that the possibility is severe in the north and north eastern side of Delhi and is very less in the western side of the city. In the south and central part of the area where shear wave velocities of the soil strata is ≥180 m/s the possibility of liquefaction is unlikely and in Vijayawada city, the occurrence of liquefaction is likely at several locations especially in Patamata, Autonagar and Kanuru.

All of the civil engineering structures involve some type of structural element which is in direct contact with soil. To estimate the accurate response of the superstructure it is necessary to consider the response of the soil supporting structure, and is well explained in the soil structure interaction analysis. Many attempts have been made to model the SSI problem numerically; however the soil nonlinearity, foundation interfaces and boundary conditions make the problem more complex and computationally costlier. To overcome this problem the attempt has been made to optimize the computational efficiency by applying the equivalent pier method for the deep foundation system. In this research paper the L-shape 11 storey building supported by a pile foundation with homogeneous local soil condition is analyzed for dynamic loading including the SSI effect. The significance of the SSI effect has been studied by comparing the responses of the system for fixed base and flexible base condition. A new approach has been proposed to provide simplicity in SSI modeling and reduce the computational cost (both memory and time wise). The approach includes the applicability of the equivalent pier method for the asymmetrical pile groups system, including SSI effect of the pile foundation system. The approach is validated for group effect and found that equivalent pile method can successfully be adopted and helps to reduce the computational cost of SSI problem. To understand the applicability of EPM approach, the parametric study has been carried out for different input of earthquakes and soil types. In accordance with this the three distinct earthquakes, including 1995 Chamba (M = 4.9), 1999 Uttarkashi (M = 6.9) and 2001 Bhuj (M = 7.7) and soil types including cohesive, cohesionless and C-Phi soils have been considered for SSI analysis. The study observed that, earthquake magnitude and soil type shows the major impact on the response of the SSI system.

The damage induced by seismic events is well known among the civil engineering, geological and seismological community. Seismologists and geologists who study this hazard at a deeper level are concerned more with the history and cause of earthquake events rather than their effects. When seismic energy is released during an earthquake it passes from the bedrock, then through the soil and to the sub structure through which it is transmitted to the superstructure. Liquefaction phenomenon is a consequence of earthquake induced pore water pressure in the soil due to this released energy. Various deterministic and probabilistic based methods have been developed in the recent past after various case histories. It is crucial to understand the performance of critical structures such as pipelines, road networks, nuclear reactors etc during liquefaction. The current chapter majorly focuses on the liquefaction assessment using numerical modeling.

The engineering behavior of marine clay is very different than that of the moist and dry clay because of its structural and mineral composition (1). Marine structure is subjected to the waves which create a cyclic stresses inside the soil mass (2). The huge storage tanks experiences a heavy wind and current load which produces a adverse effect in the soil settlements. In this paper a cylindrical reinforced cement concrete tank with diameter 100 m and 40 m height founded on soft marine clay of undrained shear strength of 10 kPa is considered for the analysis. The huge pile group is modeled by equivalent pier method and interaction factor method for the full and empty loading conditions. Settlement including the soil pile interaction has been estimated for both the cases mentioned above for different pile configuration including pile length, diameter and spacing of piles in a group. It has been observed that the spacing of the piles plays a vital role in estimating the settlements and stresses. With the comparison of the equivalent pier method (EPM) (8) and interaction factor method (IFM) for settlement estimation, the later is found to be more suitable for interaction analysis to achieve the safety of the tank.

Experience from past earthquakes has demonstrated the vulnerability of structures to seismically induced ground deformation. During earthquake, soil can fail due to liquefaction with devastating effect such as land sliding, lateral spreading, or large ground settlement. The phenomenon of liquefaction of soil had been observed for many years, but was brought to the attention of engineers after Niigata (1964) Alaska earthquakes (1964). Liquefaction is a phenomenon in which the strength and stiffness of a soil is reduced by earthquake shaking or other rapid loading. Liquefaction and related phenomena have been responsible for tremendous amounts of damage in historical earthquakes around the world (Borchardt, 1991). During the Bhuj earthquake on 26th January 2001 (M=7.7) lot of damages had been occurred due to liquefaction and other ground failures (Rao and Mohanty, 2001a). From these investigations it was observed that a vast majority of liquefaction occurrences were associated with sandy soils and silty sands of low plasticity.