Pile foundations are provided for structures, where soil at the top layers possesses low bearing capacity. A comprehensive understanding of pile foundation located in liquefiable soils is a key requirement to enable designer to arrive at an economic design and for safe performance of structure during its intended service life. The failure of various structures on pile foundation system in liquefied soil subjected to earthquake load shows limitation of present methodologies available for design. Hence, study of pile foundations in liquefiable soil under earthquake loading attracted attention of researchers over many years. In addition, many governing factors, as compiled by researchers during analysis and design of pile foundation in liquefiable soils, need to be critically analysed. Therefore, in present paper comparative aspects of various issues addressed by different researchers are presented. It briefs about various International Codes followed in design and analysis. This review article also provides analytical study/numerical model developments, and experimental works performed by various researchers with an effort to bring out the progress in analysis and design. The current paper also discussed various behavioural issues, design aspects, recommendations by researchers dealing with proablems of pile foundation considering liquefaction condition of soil and some exemplary cases.

To study the dynamic responses of a civil engineering structure, shake table tests and centrifuge tests are more commonly used. Due to various limitations, sometimes it is not possible to carry out the required tests on original structures, but it becomes inevitable to perform experiments by changing the scale (scaled up or reduced scale) in a model from the prototype. The geometrical shape and materials of the scaled model may be different from the prototype. In the present study, a detailed presentation is made about the design philosophy, limitations, advantages of shake table tests, as well as centrifuge tests. It is also detailed that the principles and approaches used in the development of the model in the scaled format of a prototype. Stepwise, it is illustrated the development of a scaled model, extrapolating the results in a prototype. The present paper will be useful to researchers performing dynamic experiments using shake table tests or centrifuge tests with a scaled model.

In the present study, the response of the pile foundation subject to seismic load in both non-liquefied and liquefied soil is investigated by developing a mathematical code. Further, the response of pile foundation is compared for both the cases of soils. It is observed from the results that the responses of pile foundation are different in both cases. It is also observed from pile response that pile embedded in liquefiable soil warrants more attention. Therefore, the evaluation of the liquefaction potential of soil is very much essential before planning of construction of any important facility or structure. Hence, in the present study, a mathematical code is also developed to evaluate the liquefaction potential of soils. A parametric study is also carried out for pile foundation in liquefied soils using developed code. During an evaluation of liquefaction potential of soil at any depth using the methods available in the literature, the amax (maximum acceleration) at ground level is used. In the present study, a method is also proposed to evaluate the liquefaction potential of soil considering the actual acceleration of soil at the depth of concern and including the soil properties, site parameters that are responsible for soil acceleration amplification.

In the present paper, we evaluate the liquefaction potential of a selected site using standard penetration test results available for the site and investigate the effectiveness of engineering measure by way of ground improvement technique adopted to mitigate earthquake-induced liquefaction in soil. The various field tests of soils and field testing through pile load test carried out to examine the improvement in soil properties are discussed. It is observed there is an appreciable improvement of liquefaction resistance of soil using cement based grouting measures for the selected soil site. The analysis results show that there is significant reduction in vertical settlement (55%) as well as lateral top deflection (65%) of the pile in post-grout scenario when compared to those of pre-grout scenario.

In the present paper, the soil-pile model is tested on a shake table subjected harmonic load. A reduced-scale model (1:20) based on the similitude rule for a group of piles with a pile cap is used in the present study. The sinusoidal base excitation with varying frequencies in the range 3 Hz to 12 Hz and base acceleration ranging from 0.05 to 0.3 g are used as input base excitations for shake table testing. The amplifications at various depths of a cohesionless soil deposit without and with a group of piles are studied using shake table testing. Also, behaviour of group of piles embedded in soil is investigated in terms of variation in the strain levels and pile bending moment along the depth without and with pile cap mass with floating tip condition. It is observed from test results that the amplification of acceleration near top of the soil column is up to 4.266 times the base acceleration in the soil only cases. However, the amplification of acceleration near top of the soil column is up to 4.00 times the base acceleration when the model piles are placed inside the soil and is up to 4.66 times the base acceleration at the pile cap level. It is also observed that, when the model piles along with pile cap and pile cap mass are placed inside the soil, the amplification on base acceleration near top of the soil column and at the pile cap level are up to 3.986 and 4.67 times, respectively. The pile bending moments are evaluated by mounting the strain gauges at different depths along the pile surface. These are also evaluated using analytical methods, and the comparison of the results shows reasonable agreement. It is also observed that the pile bending moment at centre pile is lesser compared to pile bending moment of corner piles which may be attributed to effects of confinement. The present study will be useful guide for pile designers to obtain pile response under dynamic loads.

Foundations supporting superstructure need to be designed for the reactions due to wind/seismic loads in addition to dead load, imposed load of the superstructures. In case of tall structures like chimneys, the base moments will be high and hence need to be checked for both maximum and minimum bearing pressures and ensure that the safe bearing pressure is not exceeded and also the possible uplift if any is limited to the guidelines suggested by the codes. In the present study, a foundation raft supporting 60 m high RCC ventilation stack is analyzed for various load combinations. The effects of soil-structure interaction have been considered in the detailed finite element analysis carried out. Soil-structure interaction (SSI) effects in both static and dynamic case with and without embedment effects are considered. In the foundation design, uncertainties in SSI are also accounted. The results obtained for various aspects mentioned above have been discussed.

Prior to construction of important civil engineering structure at sea bank or offshore location, it is essential to perform geotechnical investigations. It helps obtaining various geotechnical parameters used in analysis, design, and construction. It is commonly observed, soils near beaches or offshore locations possess lower bearing capacity, prone to liquefaction and structures exposed to waterfront condition. Hence, if any structure is planned, pile foundations are commonly recommended. In the present paper, geotechnical investigation is presented of a selected site planed for construction of onshore and offshore structures. Further, various engineering soil parameters are evaluated from it. Liquefaction potential of soils evaluated adopting methods available in literatures. In the present paper, the considerations followed during design of pile foundations supporting offshore structures considering liquefaction of soils are presented. Also, site amplification studies have been carried out for the selected site using DEEPSOIL software.

Wind velocity data modeling plays a crucial role for the estimation of wind load and wind energy. Apart from these, the same modeling must also be used in the load cycle analysis of fatigue failure in slender structures to address periodic vortex shedding. Most authors fitted the entire available range of wind velocities of various locations using Weibull models. However, they did not check the validity of the model in describing the range of extreme wind velocity. In this work, the validity of Weibull models for describing parent as well as extreme hourly mean wind velocity data for four places on the east coast of India has been checked. While it predicts lower wind speeds accurately, the Weibull model has been found to become inappropriate for describing wind velocity in the range of extremes, i.e., above a certain threshold value. Therefore, this article focuses on the techniques of determining a limiting wind velocity beyond which the Weibull distribution is rendered unsuitable. In the range where the Weibull distribution fails, various extreme value distributions, such as Gumbel, Fréchet and reverse Weibull distributions have been compared, thereby determining the best estimator for each location.

In this study shear wave velocity (V (s) ) and standard penetration test (SPT) N values up to the bedrock have been measured by multichannel analysis of surface wave and drilling of boreholes at 51 locations in shallow bedrock sites of South India, as part of the intraplate seismic region of India. Testing covers the major cities as Bangalore, Chennai, Coimbatore, and Vizag in South India. Drilling of boreholes in the above locations shows that the top surface consists of soft to very dense soil followed by very hard Granitic rock. N values are measured up to 100 and values beyond 100 were reported as rebound. Soil thickness of these locations varies from 1 m to about 20 m. The measured N and V (s) values are used to generate correlations between N and V (s) values for each city and also for the combined data by excluding and including SPT N of 100 for rebound layer. Further the applicability of the V (s) and N correlations developed for a particular site to other sites in the same region has been studied and it has been found that the site specific correlations are more accurate. The correlations developed for other cities display high percentages of error, even though the sites are similar in geology and soil type. Additionally, the developed empirical correlations have been compared with the existing worldwide correlations using logarithmic Euclidian distance (logED). The logED value has been estimated between the measured and calculated lower logED respectively for different cities and arrived the best suitable predictive equations for the four cities. Lower logED value between the measured and calculated V (s) corresponds to better empirical relationship.

Mumbai city is the financial capital of India with the highest population density and formed by reclamation of land over time from original seven different islands. As per Indian seismic design code IS 1893-Part 1, Mumbai city is located in Zone III, hence may experience moderate intensity earthquake which may lead to liquefaction of some typical soil sites of Mumbai city. In this paper, using available recent procedures for liquefaction analysis, seismic liquefaction hazard maps for Mumbai city are prepared. Also the typical coastal soft soil strata of Mumbai may be prone to soil amplification for different bed rock earthquake motions and the present study shows that typical ranges of soil amplification factor for bed rock acceleration are 1.2–3.5. Hence, construction of pile foundation, which is mostly used for the effective use of the most precious land of Mumbai city for construction of high rise buildings, need special attention in design when such possibly liquefied soil strata with soil amplification during moderate earthquake intensity is considered. Present study shows the response of pile foundation in both non-liquefied and liquefied soil by considering both kinematic and inertial responses in terms of displacement and bending moments of piles, which are necessary to consider for seismic design of pile foundation in typical Mumbai soil.

Liquid storage tanks are used for storing water, inflammable liquids and other chemicals. Thus storage structures are very important for public utility and for industries. Such structures shall be designed for lateral loads such as wind loads/earthquake loads. Earthquake is a sudden movement of the earth caused by the abrupt release of strain that has accumulated over a long time. This dynamic vibration of lateral movement affects structural strength and its behaviour. During the recent past earthquakes, many failures of liquid retaining structures are observed and thus there is a need to understand the behaviour of liquid retaining structures and to consider the latest advances in the design of such structures so that they are not vulnerable under earthquake loads. In the present study, behaviour of a typical ground supported structure under earthquake loads is studied using analytical solutions based on the codes/guidelines prevalent and the same are compared with the detailed dynamic finite element solutions. Both the convective and impulsive mode are captured in the detailed dynamic analysis and the time periods of respective modes of vibration are compared with the available guidelines. Good agreement in results is obtained using the computer based analysis. Behaviour of liquid storage tanks under earthquake loads has been studied as per Draft code Part II of IS 1893: 2002 [1]. A FEM based computer software is used (SAP2000) for seismic analysis of tank and finally their results are compared.

Response of piles due to lateral loads considering soil structure interaction has evolved over the years with various solution techniques available due to the contribution of various researchers in the field of geotechnical engineering. In the present study, various solution techniques available on the behavior of single piles under lateral loads are discussed thoroughly and parametric studies are carried out to obtain the response of single piles with floating tip in cohesionless soils, using elastic continuum approach. Analyses are also performed using versatile modulus of subgrade reaction approach. In general, elastic continuum approach though realistic, complexity exists in estimating the Young's modulus of soil, whereas modulus of subgrade reaction approach besides its simplicity can also account soil nonlinearity and thus preferred by many designers over elastic continuum approach. From the pile response so obtained by using both these methods, algebraic equations are proposed for free headed floating tip piles and also for fixed head floating tip piles for semi rigid and flexible type piles.

Soil pile interaction studies have evolved over the years and the contribution by various researchers in this field has lead to the development of various methods viz. modulus of subgrade reaction approach, elastic continuum approach and finite element techniques for estimating the pile response.The advantage of subgrade reaction approach over elastic continuum approach is that besides its simplicity, it can also account for material non-linearity. The more realistic approach is elastic continuum method, however, the pile response based on this method, depends on the accurate estimation of soil young’s modulus. In the present study modulus of subgrade reaction is related to young’s modulus of soil using empirical relations and pile response for various stiffness ratio’s is obtained by using both modulus of subgrade reaction approach and finite element based solutions for homogeneous soils, soils with linearly varying stiffness and for two layered soils with constant but different soil stiffness. With the pile response so obtained by both these methods, algebraic expressions have been proposed for pile head deflections and maximum pile bending moments for homogeneous soils, soils with linearly varying stiffness and for two layered soils with constant but different soil stiffness.

Design of piles under lateral loads requires estimation of ultimate load carrying capacity of the pile and also, the pile deflections need to be evaluated to determine the allowable loads. For estimating the pile response, structural engineers invariably utilize the simplified method prescribed in the Indian code IS 2911-2002 (Indian Standard Code of Practice for Design of Pile Foundations, 2002). The method is based on replacing the pile soil system by an equivalent cantilever, the length of which is a function of subgrade reaction of the surrounding soil and the pile geometry. However, the method described is applicable only for flexible piles, where the maximum depth coefficient L/T is equal to or exceeds 4.0. To estimate the pile response for rigid piles, simplified procedures are not suggested and hence in the present study, an attempt has been made to evaluate the pile response under lateral loads using detailed soil–pile analysis. Parametric studies are carried out for various pile lengths and various soil stiffness. The pile responses thus obtained are compared with the method given in IS 2911-2002. It was observed that the pile response based on IS 2911-2002 compared reasonably well with the detailed soil–pile model even for L/T ≥ 2.5. However IS 2911-2002 underestimates the pile head deflections for L/T < 2.5 for both free headed and fixed head piles and hence detailed soil–pile analysis is essential for such situations. The variation of pile response with soil stiffness is also evaluated using these methods and the results are presented. The soil–pile analysis is carried out using subgrade modulus approach. The soil stiffness is assumed to vary linearly along the pile depth and hence the study is applicable for cohesionless soils which can be used for practical design of single pile subjected to lateral loads.

Analysis of pile foundations for earthquake loads requires the consideration of inertial loads that result from the soil-pile-superstructure interaction, as well as the evaluation of kinematic interactions that result from the movement of the surrounding soil and the pile. Such soil-pile interaction analyses must consider the stiffness degradation that results from earthquake loading. In the current study, the soil-pile interaction analysis considers stiffness degradation effects for a range of earthquakes with different amplitudes [maximum horizontal acceleration (MHA)], mean time periods, and different durations of earthquakes. Effects of both kinematic and inertial interactions are evaluated using a seismic-deformation method. A computer program was developed using MATLAB for the analysis. Results of a ground-response analysis obtained from a separate study were used for the soil-pile interaction analysis. Pile response for kinematic interactions were validated with the available theoretical solutions in the literature. In addition, kinematic pile response was compared with field observations for an actual earthquake, and the results are presented. Parametric studies were carried out to understand the effect of the presence of a liquefying soil layer, depth of the liquefying layer, etc., and the results are presented. The results indicate that the effect of the depth of the liquefying layer has a significant influence on the pile-bending response and that the peak bending moment occurs at the interface of the liquefying and nonliquefying layers. (C) 2013 American Society of Civil Engineers.

Any earthquake event is associated with a rupture mechanism at the source, propagation of seismic waves through underlying rock and finally these waves travel through the soil layers to the particular site of interest. The bedrock motion is significantly modified at the ground surface due to the presence of local soil layers above the bedrock beneath the site of interest. The estimation of the amplifications in ground response due to the local soil sites is a complex problem to the designers and the problem is more important for mega cities like Mumbai in India, where huge population may get affected due to devastations of earthquake. In the present study, the effect of local soil sites in modifying ground response is studied by performing one dimensional equivalent-linear ground response analysis for some of the typical Mumbai soil sites. Field borelog data of some typical sites in Mumbai city viz. Mangalwadi site, Walkeswar site, BJ Marg near Pandhari Chawl site are considered in this study. The ground responses are observed for range of input motions and the results are presented in terms of surface acceleration time history, ratio of shear stress to vertical effective stress versus time, acceleration response spectrum, Fourier amplitude ratio versus frequency etc. The typical amplifications of ground accelerations considering four strong ground motions with wide variation of low to high MHA, frequency contents and durations are obtained. Results show that MHA, bracketed duration, frequency content have significant effects on the amplification of seismic accelerations for typical 2001 Bhuj motion. The peak ground acceleration amplification factors are found to be about 2.50 for Mangalwadi site, 2.60 for Walkeswar site and 3.45 for BJ Marg site using 2001 Bhuj input motion. The response spectrum along various soil layers are obtained which will be useful for designers for earthquake resistant design of geotechnical structures in Mumbai for similar sites in the absence of site specific data.