Proceedings of the Indian Geotechnical Conference 2022 Volume 1

Compaction is the process by which mechanical energy is used to bring the densification and stabilization of the soil matrix giving the soil enough strength. The compaction characteristics can be obtained by performing Proctor Tests with varying compactive efforts. The fruitful compaction of soil is imperative toward the stability and function of structures. It is observed through different literature works that the existing relationships between compaction characteristics and physical properties of fine-grained soil, like plastic limit, have not been palatable as the plastic limit obtained from the conventional thread rolling method is prone to human error. So, an endeavor has been made to develop relations relating optimum moisture content and maximum dry unit weight with plastic limit, determined by cone penetration method, which eliminates its inclination toward human error. It has been shown in previous works that the 3.92 N-30° cone can be used to determine the plastic limit of soil. These relationships with the plastic limit have been found to relate very well with the optimum moisture content and maximum dry unit weight. Moreover, an effort has been made in this work to develop correlations between maximum dry unit weight and optimum moisture content with different compaction energy and other physical properties such as plastic limit, plasticity index, and degree of saturation at the maximum dry unit weight.

Infrastructure will play a vital role in the growth of developing nations like India. Pile foundations in soft soil deposits have increased significantly as a result of the scarcity of land and the need for high-rise structures. Soil–structure interaction is often omitted in conventional design practices considering the base as fixed, which can lead to an underestimation of forces and displacement throughout the system. This study aims to investigate the influence of the length of the pile to diameter ratio (L/d) and embedded length to length of pile ratio (Lb/L) incorporating soil–structure interaction (SSI) using a numerical tool SAP2000. The seismic analysis of a 25-storey high-rise building has been performed using response spectrum analysis for zone V as per IS 1893: 2016 to assess the seismic response of superstructure consisting of lateral displacement, inter-storey drift, base shear, and column moment. A parametric study has been carried out for different L/d and (Lb/L) ratios such as 30, 24, 20, and 0.042, 0.083, 0.125, and 0.167. The numerical results show that the pile foundation with less L/d and Lb/L ratio offers the least lateral deformation, inter-storey drift, base shear, and column moment.

The study of individual effects of morphological properties of sand grains, such as their size, shape, and surface roughness, is of great importance while dealing with problems of liquefaction and cyclic mobility, as these microscopic characteristics significantly influence the physical, mechanical, and hydraulic behaviour of sands. 3D printed granular media with representative morphological characteristics of natural sand grains enable us to control particle size and shape, thus permitting a comprehensive investigation of the effect of individual parameters. This study aims to critically evaluate the capability of 3D printed media reproduced at different scales to capture the morphological characteristics of natural sands through a well-established image analysis method. A completely automated image analysis procedure characterizes the 2D morphology indices of 3D printed media and natural sands. The effect of the scale of reproduction of the 3D printed materials and other critical parameters on the reproducibility of morphological characteristics of the original medium is assessed through an analytical comparison of these indices.

Conventionally, liquid, plastic, and shrinkage limits are considered as plasticity characteristics of natural fine-grained soils. Different approaches to estimating liquid limits itself demonstrate that the concept of a liquid limit and the mechanism governing it are not the same Sridharan and Prakash (Proc Inst Civ Eng Geotech Eng 143:235–240, 2000 [1]). In the present experimental study, five natural fine-grained expansive soils having liquid limit range (50–100%) were used. The three characteristic water contents, i.e. it was feasible to calculate the free swell limit (WFS), setting limit (WSL), and shrinkage limit for plain and fibre-reinforced expansive soils for different percentages by adjusting the initial water content. There are relationships between starting and final water contents as well as sediment volume and liquid limit. The experimental study’s measurement of the equilibrium sediment volume shows good agreement with the established procedure for determining liquid limits. Using linear regression analysis, correlations were developed between index properties, plasticity characteristics with the compaction characteristics for varying water contents along the compaction curve for different energy levels.

Alkali as pore fluid due to contamination from various sources affects the soils in different ways depending upon the mineralogical content present in the soil, and the concentration and duration of pore fluid. Properties of the soil get altered by the contamination of alkali. So, the present study aims to understand the mechanism of soil–alkali interaction and also to have a better knowledge about the changes in swelling, strength characteristics, and index properties in the soil due to the alkali interaction with the soil. Thonnakkal Clay and Kuttanad soil are selected to study the changes that occur when they are exposed to sodium hydroxide alkali contamination from various sources and to better understand the behavior of soil when contaminated with sodium hydroxide at 1 N and 4 N concentrations with varying percentages of 2.5, 5, and 10% by weight of the sample. The variations in index properties, strength characteristics, and swelling behavior are reported in this paper.

The foundations which were placed on problematic soils like expansive soils are causing the swell-shrink behaviour due to moisture changes and the structures built upon these soils are experiencing failures. There are multiple specified foundation approaches to address the swell-shrink issues brought on by these soils. The current study deals with the volumetric changes of natural fine-grained soils having varying liquid limits (WL = 58, 66, 74, and 85%) blended with Recron 3s fibre (0.5, 1, 1.5, 2, 2.5, and 3%). Swelling potential (Sp) is compared with index properties (plasticity index and shrinkage index) with variation in fibre percentage. Swell pressure (Sw) tests were conducted by the constant volume method for the optimum fibre content having different compaction energy levels (IS light and heavy compaction). For soils having a liquid limit range of 58–66%, the Si decreases and then has an increasing tendency. Sw was not affected to a greater magnitude by the inclusion of optimum fibre content, for varying energy levels compacted at OMC and MDD. Irrespective of the energy levels, an increase in the liquid limit of the soils causes an increase in the optimum fibre content (compacted at the maximum magnitude of MDD).

Coal ash is utilized as structural fill material in highway and railway construction. Shear strength tests are commonly conducted on specimens consolidated under isotopic conditions (IC); however, stress conditions in the field are anisotropic (horizontal and vertical stresses are not equal). The current study focuses on evaluation of shear strength and pore pressure response of coal ash consolidated under K0 conditions simulating field conditions more accurately. Two series of CU triaxial testing were conducted on coal ash under IC and K0 conditions at different mean effective stresses (at the end of consolidation) ranging from p′ 0 = 50, 100, 150, 200, and 300 kPa. Peak stresses for K050 and K0100 tests were observed to be less as compared to IC50 and IC100, respectively. For IC specimens, pore pressure was obtained to be less dilative with increasing pꞌ0; however, the behavior was in contrast for the K0 specimens. For the higher range of mean effective stresses (pꞌ0 = 100, 200, and 300 kPa), peak deviatoric stress showed a large increase for both IC and K0 specimens with increasing pꞌ0. For the same pꞌ0, the K0 specimen exhibited lower peak stress as compared to IC specimen although a smaller difference for higher pꞌ0 was observed. The contractive pore pressure response was observed to increase with increasing pꞌ0 for IC specimens. However, K0 specimens exhibited a significant increase in dilative pore pressure response with increasing pꞌ0.

Pile response to a vertical load can conveniently be studied using load-deformation behaviour of piles. The load-deformation behaviour of pile can be determined either by conducting an expensive field test or predict numerically using the in situ soil parameters. Several approaches have been proposed to predict the load-deformation behaviour numerically. Two such approaches often used are finite element (FE) analysis and load transfer method. FE analysis is expensive and requires a very skilled person to execute the analysis. The load transfer method is much simpler, easy to use for the analysis and recommended by the API. In the load transfer method, the soil structure interaction has been expressed in terms of t-z curve, the t represents shear stress at the pile shaft, and z is the relative deformation between soil and pile at the interface. This t-z curve varies with depth, soil-pile interface friction angle, and the pile installation. This paper critically reviews several t-z curves based on the theoretical, empirical, semi-empirical, elastic, and nonlinear methods that have been used in the past to study the load transfer concept of the single pile. The development, limitation, and range of applicability of these models are also explored in detail.

Berthing structures are one of the main facilities constructed in ports, which mainly interact with the incoming vessels while berthing mooring and repairing. The berthing structure and breakwaters constitute most expensive structure in any ports. Soil found in the coastal region is mainly of soft marine clay which is having low shear strength due to consolidation. Hence pile foundation are mostly adopted for the construction of heavy structures in such soil conditions. Most of the coastline surfaces are sloped in nature and the vertical piles are often subjected to lateral loads in addition to axial loads. Soil structure interaction has to be considered as a dominant factor when structure is built on weak soils. In this paper, soil structure interaction of single pile located in a berthing structure was studied numerically with PLAXIS 3D software. The response of pile was analyzed by considering various factors such as magnitude of lateral load, behaviour of ground and sloping surfaces, position of piles, loading direction. In single pile analysis, pile lateral capacity of ground surface and sloping surfaces was compared. It is observed that lateral capacity decreases when surface changes from horizontal to slope.

In the area of Feldolling, a village south of Munich, Bavaria, Germany, a flood water retention basin for the river Mangfall is planned and still under construction. In the event of heavy rains or seasonal ice-melting in the Alpes, the flood-prone region can suffer from severe damage to the infrastructure and the residential areas. Those events can therefore even threaten people´s lives. The planned flood retention basin will store more than 6 Mio m3 of water. For the construction of the retention basin, the authorities are building a few dikes of different lengths in addition to a dam to capture the flood water in the retention basin. The inner sealing and the underground cut-off barrier of one of the dikes was constructed using deep soil mixing wall. The implemented deep soil mixing technique is the Mixed-In-Place technology (MIP). The MIP wall had a width of 550 mm and reached a maximum depth of 23 m. The soil conditions were not uniform and varied from gravel and sand to silt and clay. The cut-off wall had to have a strength not exceeding 3 MPa and should be 1.5 MPa on average. To take into account the different soil characteristics and to achieve the required material properties, a lab testing program took place before construction.

Seismic Soil-Structure Interaction (SSSI) is an important aspect in the satisfactory long-term performance of buildings. Assessments of seismic demand of the buildings supported over rigid/fixed base are more well established. Due to the reduction in flexural and torsional stiffness, irregular structures are more vulnerable to damage during seismic disturbance. The present paper investigates the effects of SSSI for irregular building supported on pile foundation. This study utilizes three-dimensional numerical approach to investigate the seismic response of a mid-rise building. Two different configurations of plan irregularities and two recorded ground motions are being considered in the present study. Different parameters such as lateral displacement, interstorey drift, base shear of irregular building considering the effects of SSSI are systematically investigated and reported here. The comparative study amongst different lengths of pile foundation supporting the regular and irregular buildings brings out the importance of SSSI on their performance. Results indicated that considering the effects of SSSI amplifies the lateral displacement, interstorey drift and base shear to a larger extent for irregular building in comparison with regular building supported on pile foundations.

In Geotechnical Engineering, consolidation of clays and its in situ prediction plays an important role, as the calculation of the possible settlement of any structure is crucial in any foundation design. The calculation of the settlement is now carried out based the theory proposed by Karl Terzaghi. Over a period of time, many limitations of this theory have been identified. In this paper, an attempt is made to derive a new equation for accurately predicting the primary consolidation of clays. As predicted settlement values using conventional method vary much from the actual, most of the previous attempts were to correct or modify the value of the coefficient of consolidation. However, these corrections have not yielded desirable results to achieve accurate predicted values. The derivation of the conventional equation is revisited and a modification is proposed. The procedure is drawn in similar lines as that of the existing method to retain all the relevant terminologies that have been established in the field. This is done by modifying the relevant coefficients and factors. The newly derived expressions are explicit and direct for predicting the settlement at any stage. An example is also illustrated to demonstrate its validity and applicability.

Soil-structure interaction plays a significant role in the design of the structure. The coupling effect between the structure and soil media is termed as soil-structure interaction. Conventional design practice needs to modify based on the soil-structure interaction effect and must be included in the standards of regular design practices. The study is specifically focused on the soil-structure interaction of the G + 3 building for three different types of soil, i.e. hard soil, medium soil, and soft soil considering the Mohr–Coulomb soil model using finite element-based software ANSYS. The effect of soil-structure interaction is observed on the vertical reaction, horizontal reaction, and bending moment at the footing base considering the Mohr–Coulomb soil models. The parameters are observed at the corner, edge, and central footing of the building. To observe the effect of soil-structure interaction, flexible base model is compared with fixed base model. The effect of the SSI increases as the soil changes from hard to soft soil. The variation of parameter with location of the footing is studied, which shows the vertical reaction at central footing shifts towards outer footings, i.e. edge and corner footings, while the central footing shows a greater intensity of horizontal reaction and bending moment compared to edge and corner footings.

Soil is material formed due to weathering and erosion process of rocks. Water in contact with some type of soil causes problems in civil activities. These problems include swelling, dispersing, and collapse of soil materials. Structures built on collapsible soils may settle if saturated under loading. Formations of collapsible soils are due to geologic deposits of silty or loamy material such as loess which are loosely cemented by calcium carbonate and are mainly deposited by the wind. Field observations and laboratory tests can be useful to identify problematic soils. Some properties of soils are helpful to estimate the collapsibility potential of soils. In this present paper, a case study of a project in the northern part of India has been considered to evaluate the geotechnical properties of soil materials. Laboratory investigations such as liquid limit, plastic limit, plasticity index, moisture content, dry density, and one-dimensional consolidation tests on 19 undisturbed soil samples collected at various depths from two different locations were carried out. Most of the samples were Silty Sand and were Non-Plastic as per IS Classification of soils. Identification of the collapsible nature of the soil was determined by conducting Double Oedometer tests. Void ratios arrived by conducting Double Oedometer tests were used for measuring collapse potential. The severity of foundation problems associated with the collapsible soils has been correlated with the collapse potential, which shows that all soil samples fall under moderate trouble nature.

Geotechnical properties of soil estimated from laboratory tests are generally affected by sample disturbance. It is difficult to deal with sample disturbance during the laboratory testing of soft soil. Estimation of preconsolidation stress from laboratory tests is highly affected by sample disturbance. The concept of preconsolidation stress is useful in analyzing and predicting settlement behavior of soft soils. Hence, accurate determination of preconsolidation stress is important for settlement analysis. Estimation of preconsolidation stress depends on graphical methods. Many graphical approaches are available in the literature for estimation of preconsolidation stress from the laboratory consolidation tests. In this study, the consolidation test data is taken from (Egypt, California, Vietnam and India) different locations around the world. The effect of sample disturbance on the compression curve for estimation of preconsolidation stress and settlement of soft soils is presented. The approaches used for determining the preconsolidation stress from the consolidation tests are based on graphical interpretation procedures of void ratio (e) versus effective stress $$\left( {\sigma^{\prime}} \right)$$ σ ′ data. The methods used in this study are semi-logarithmic (Casagrand, 1936 and (Schmertmann in The undisturbed consolidation behavior of clay. Transactions of the American Society of Civil Engineers, pp 1201–1233)). The true in situ settlements from the true in situ compression curves are estimated and compared with the settlements obtained from the laboratory curves..

This paper describes a comparative study of the particle size distribution of fine-grained soils done by adopting hydrometer and laser diffraction (LSD) methods. In general, these analyses are adopted for fine-grained soils less than 75 μm are classified as silt (75–2 μm) and clay (< 2 μm). However, the methods are based on different methodologies they may not obtain the same results of clay and silt fractions. The hydrometer method is based on sedimentation analysis (up to 1 μm), whereas the LSD is based on laser diffraction analysis (0.4–2000 μm). Although the hydrometer was time-consuming, it is typically preferred for the particle size distribution of fine-grained soils. The obtained values of clay and silt fractions are uncertain due to the influence of factors such as temperature, particle shape, mineralogy, and predominant molecular weights of the elements in the soil. The results obtained from these methodologies are critically evaluated and presented in the study.

In this research paper, significant parameters that affect the shear behavior of river sand collected from Rishikesh (Uttarakhand) are studied. Classification and geotechnical properties of river sand are found as per standard codes. The effect of the height of fall and time of shaking on the relative density of river sand is found. After that effect of the size of the specimen, relative density and strain rate on shear properties are studied. Relative density is found up to 16 min of vibration with a step increment of 2 min. Direct shear test results of 300 mm and 60 mm shear boxes are compared to study the specimen size impact. The strain rate of 1.25, 0.625 and 0.25 mm/min are considered to analyze the strain rate impact. Three relative densities at 50, 70 and 85% of direct shear test specimens are considered. Relative density becomes constant after a particular point of the fall height and time of vibration. Shear properties of sand are affected significantly by different test scales, strain rates and relative densities of river sand specimens.

This study focuses on developing the advanced analysis procedure for increasing the underground utility resolution using the RADAN software. The chop-off of the time-domain signal and frequency band filtering approach are adopted to improve underground utility resolution. The rebars of rigid pavement symbolically appear in the form of hyperbolic rings as an output of the GPR data. These small hyperbolic rings reduce the resolution of underground utilities, and further difficulty arises in identifying the appropriate location of underground utilities. Therefore, the resolution of underground utilities is compared with the proposed processing steps of frequency band filtering with the incremental and constant time chop-off approach. The incremental time chop-off approach results in a high resolution of underground utilities compared to the constant time chop-off approach in the GPRs output. The performance of the proposed processing steps is explored with the six different earth profiles. The findings of this study demonstrate that (1) GPR data collected using a 900 MHz antenna is highly sensitive, and removing the RADAN spectrum of rebars zone is an effective way for utility detection of depth less than 1 m, and (2) High rebars resolution is obtained using 900 MHz compared to 400 MHz.

Extensive geotechnical investigations are carried out for designing crucial structures of a nuclear power plant (NPP). As these structures enforce heavy loads on the foundation, it is imperative to evaluate the properties of subsurface rocks up to sufficient depth to ensure the plant’s safety. A primary requirement for design of nuclear power plants is they withstand dynamic loads up to a predefined intensity of ground motion, without endangering their safety. The properties of foundation materials are therefore of paramount importance as they can affect the structural safety. It is here, where in addition to surface geophysical techniques, electrical and acoustic borehole geophysical logging techniques play a major role in assessing the suitability of foundation. The subsurface parameters evaluated from these studies include electrical resistivity, primary and shear wave velocities, and dynamic moduli of elasticity which form the basis of deriving the input design values for the structure. Additionally, these methods also determine the location of weak zones. This paper highlights the importance of borehole geophysical logging in assessing the foundation for NPP with two CWPRS case studies, where suitability of foundation critical structures was determined.

The cross-hole seismic tomography (CST) is a semi-intrusive method for structural/geotechnical/geological investigations in between two boreholes. The seismic waves generated by the source at different positions in one borehole are received by the array of receivers in another borehole, and signal is recorded by the high-frequency seismograph. The output of the CST method is a high-resolution image of the seismic velocity distribution between the boreholes. The CST study was carried out in two boreholes in the basaltic terrain up to a depth of 90 m and located 27 m apart. The array of receivers is fixed at 1 m spacing, and source was also placed at 1 m spacing vertically in the borehole. The objective was to know the P- and S-wave velocity distribution and presence of anomalies and to determine the dynamic rock mass properties (Poisson’s ratio and Young’s modulus). P- and S-wave velocities range from 4100 to 5000 m/s and 2000 to 2900 m/s, respectively. The paper presents details of CST methodology, geotechnical interpretation of high-resolution tomogram, and dynamic properties.

The permeability behavior of compacted fine-grained soils is of great practical importance. The permeability behavior of compacted kaolinitic soils and montmorillonite soils has been carried out for the present experimental study, for the IS light and heavy compaction energy levels. One-dimensional consolidation experiment has been carried out corresponding to 0.95ρdmax on dry side of optimum, optimum, and 0.95ρdmax wet of optimum moisture content, for the pressure ranging from 6.25 to 1600 kPa, and the consolidation parameters like Cv and mv were compared for different energy levels and liquid limit. The soils compacted on dry side of optimum are exhibiting higher values of K than wet of optimum condition. Due to the influence of fabric on consolidation process, kaolinitic soils are having higher K than that of montmorillonitic soils, irrespective of the clay mineralogical composition. IS heavy compaction energy level gives lower value of K than light compaction energy level. The magnitude of computed K from the conventional equation is always lesser than the experimental one, and also, it was influenced by the clay mineralogical composition, for both low and high liquid limit soils.

Heat stored in the earth’s crust is a potential resource of renewable and green energy to meet the global primary energy needs without producing any greenhouse gases. The majority of the geothermal resources are stored in the hot dry rocks (HDR) at a substantial deep depth as compared to hydrothermal resources. The present study illustrates an overview of the HDR resources available worldwide as well as in India. The article further discussed the available technologies to extract geothermal energy from HDR. A systematic review of the key technologies including enhanced geothermal systems (EGS) and single-well borehole heat exchanger systems is analysed in the article. A 2D numerical analysis of a single-well system with a coaxial wellbore heat exchanger has been carried out to extract thermal energy from the reservoir. In addition, the influence of various parameters on the system’s heat extraction capacity has also been investigated. The present work may aid in the development of novel enhanced geothermal systems and single-well systems with improved thermal performances.

The majority of the cost and time overruns in infrastructural projects are due to concerns related to substructures. Every project needs a detailed geotechnical investigation for cost economics, safety and to arrive at a competent load-bearing stratum for construction of foundation. The standard penetration test is an in situ method which measures penetration resistance of a standard split-spoon sampler to dynamic impacts by a standard hammer and involves several corrections to arrive at the corrected N value. Energy correction factor is a field correction tool to arrive at a normalized N value for 60% energy transfer ratio (N60) from the SPT hammer to the drill rods. IS 2131 mentions hammer drop to be a free fall but does not emphasize the need for energy measurement. It is a standard practice and quality control procedure to calibrate every geotechnical SPT drilling rig to measure the energy transfer ratio (ETR). In the present study, ETR data of 40+ geotechnical drilling rigs with different driving systems across India are presented. Consequences of overprediction and underprediction of bearing capacity for different cases are briefly discussed. The importance of the measurement of ETR is appraised, and its influence on foundation design, cost economics and safety are explored along with case studies.

Laterite soils are one of the predominant soils found in the eastern and southern region of Odisha. These soils are known to display a wide range in their engineering characteristics like plasticity, permeability, shear strength, etc. Bhubaneswar is one of the fastest developing cities in eastern India, and large parts of the city are underlain by a lateritic soil. In this study, laterite soils samples were collected from four different parts of the city, and their index properties and engineering properties like plasticity, percentage of fines, shear strength parameters (under dry and wet conditions), compaction characteristics and permeability were studied. These were accomplished using methods like the standard Proctor test, direct shear testing and falling head permeability testing. From the study, it was found that the soils had high values of maximum dry density, moderate permeability and low-to-medium shear strength characteristics. It was observed that while the engineering parameters varied in a fairly narrow range, they were mainly affected by the fines content of the soil. Investigations like this can be used for a general understanding of soil properties in the Bhubaneswar region for future infrastructural projects.

Rockfill dams are getting popular because of flexibility in nature, ability to absorb large seismic energy and suitability to any foundation conditions. Rockfill material is being used as a natural construction material for different types of civil structures like dams, embankments, roads, slope protection, coastal protection, dykes, etc. Modern heavy earthmoving equipment and locally available rockfill material make the structures and economical too. In the present paper, research and development of rockfill material (RFM) has been reviewed and presented. Large size triaxial test results obtained from the tests carried out in Central Soil and Materials Research Station (CSMRS), New Delhi, have been compared with the results of works carried out by other researches for different types of RFM. The effect of maximum particle size (dmax), confining pressure (σ3), dilatancy angle (ψ) and particle breakage (Bg) and angle of shearing resistance (ϕ) have been studied and presented. From the research and development study carried out, it is concluded that the shear strength of RFM greatly depends on dmax, σ3, Bg, ψ and gradation of material.

Soil is considered to be a highly heterogeneous material whose properties vary from place to place and at a particular place with respect to depth. For carrying out any kind of geotechnical analyses on a regional scale, geotechnical soil properties are required which is possible only after drilling large number of boreholes, which is both time-consuming and uneconomical. Digital soil mapping is a process by which soil properties are predicted on a regional scale from a known limited number of point observations. Digital soil map consists of pixels in a grid wherein each pixel has a unique geographic location and soil data. Different interpolation techniques can be used for the development of a digital soil map. Various studies have shown mixed conclusions about the accuracy of the different interpolation methods. In this paper, two commonly used interpolation methods namely IDW and ordinary kriging were applied to develop a digital soil map of the residual lateritic soils in Kerala. The results were validated using the commonly used leave-one-out cross-validation (LOOCV) technique. The accuracy was also checked by comparison of predicted soil properties with an independent soil dataset which was not used in the interpolation process. The results showed that ordinary kriging outperformed the IDW method, and therefore, it can be used for development of digital soil map of residual lateritic soils of Kerala.

This paper presents a comprehensive investigation and characterization of soil at a critical location in Yupia, Arunachal Pradesh, utilizing the combined Multichannel Analysis of Surface Waves (MASW) method. Recognizing limitations in both active and passive methods for soil characterization at shallow and greater depths, the study emphasizes the pivotal importance of incorporating optimal data acquisition and inversion parameters in any MASW survey approach. Through experimental and comparative analysis, it is concluded that the combined MASW approach offers enhanced clarity at both shallow and deeper depths, yielding more accurate shear wave velocity (Vs) profiles. The research underscores the critical role of resolution in dispersion images obtained from raw data for achieving accurate Vs profiles. By effectively integrating active and passive MASW dispersion images, this study demonstrates the efficacy of the combined MASW survey method in soil characterization, reflecting its significance for seismic risk assessment and engineering design. A detailed case study illustrates the practical application and efficacy of the combined MASW survey method in determining Vs profiles, offering valuable insights for seismic hazard mitigation strategies in the region.

Construction of structures over water bodies poses a serious challenge to design engineers as various potential cost and options must be considered by the project stakeholders. It is a challenge for designers, site team, contractors, etc., as the construction needs must be precise and meticulous in such difficult ground conditions. TechSpan® is a buried precast concrete arch. It generally consists of either single or half arch units that meet at the crown, supported by a footing sized for site specific conditions. The backfill around the arch contributes to the resistance of the entire structure, constraining lateral deflections of the arch under vertical loads (soil–structure interaction). This paper focuses on a case study which involves the construction of TechSpan® structures spanning three water bodies over challenging ground conditions. This article covers safety, design, engineering and construction methods.

Vertical component acquisition of Rayleigh wave is the most widely used technique for multichannel analysis of surface wave (MASW). Dispersion imaging of the acquired field data is a critical step in determining the in-situ shear wave velocity profile by performing inversion analysis. The presence of trapped stiff or soft layers is common in real-world situations, and identifying such irregularities from dispersion images is crucial for an accurate inversion analysis. It is well known that the presence of a soft or low-velocity layer breaks the continuity of the fundamental mode and influences the higher modes, i.e., higher modes will carry more energy. However, the presence of a trapped stiff layer does not affect modes significantly in the dispersion image. In the present study, we have investigated the role of trapped stiff layers in the dispersion energy of the Rayleigh wave. The sensitivity of the trapped layers has been quantified by analyzing the Jacobian matrix. Further, the dispersion image of the corresponding synthetic earth profile is generated from the seismogram obtained by the standard staggered grid finite difference modeling. This study shows that it is difficult to capture the presence of a trapped stiff layer using only the vertical component MASW method.

Central part of India is facing water scarcity during most part of the years. The difficult in geographical features of this area and low intensity of rainfall do not permit for constructing high dams for storage purposes. Therefore, to resolve water demand in the locality, it was proposed to construct small dams across lower and medium selected streams at different location in region. Intensive geotechnical investigations were carried out at four dam locations to ascertain the feasibility studies. Laboratory investigations such as mechanical analysis, Atterberg’s limits, proctor compaction test, laboratory permeability, one-dimension consolidation test, triaxial shear strength test, and dispersivity of soil were carried out to ascertain index and strength properties of soil. It was revealed during laboratory investigations that soil is suitable at some dam sites with clay of intermediate plasticity soil classification possessing adequate strength and engineering properties, while at other dam locations, the properties of soil were with clay of high plasticity and non-plastic silty soil in nature which is not suitable in constructing earthen dams. Efforts were made either to choose suitable borrow areas or blending of soils so as to fulfill the requirement of strength and other properties of soil. This paper presents the results of laboratory investigations of four dams and remedial measures taken for the improvement of soil properties.

Active multichannel analysis of surface waves (MASW) requires sensor placement along a straight line with equal spacing to predict the properties of sub-surface earth. However, due to the presence of different obstacles in the field, placing sensors along a straight line is not always possible. To this end, the primary objective of this study is to propose a non-straight line receiver array-based active MASW method. The proposed method follows a diverted path near the obstacle while keeping the rest of the geophones in a conventional straight line before and after the shift. Sensors are shifted on an arc of a circle, with the source acting as the center of this circle. Therefore, the distance between the source and shifted sensors remains the same as their original position. This simple maneuver enables us to use existing wavefield transformation techniques without any modification. Multiple field experiments are performed using different non-straight line arrays. Dispersion images obtained from the proposed method resembled the outcomes of a conventional active MASW survey.

There is an acute scarcity of water during peak summer season in Andaman & Nicobar Islands. Most of the rainwater is wasted during rainy season. If storage facility is available by constructing dams, rainwater could be entrapped for further use. Absence of perennial rivers and need for drinking, irrigation and other purposes, it was proposed to construct a dam across a small stream to store water to encounter such problems. This paper presents foundation investigation at various locations such as dam axis, left and right abutments, and upstream and downstream of dam axis. There was thick layer of about 6 m overburden of matrix material including boulders of different sizes mixed with sand silt and clayey soil at the dam axis and exposed rock could be seen at some locations. It was not possible to carry out SPT testing and undisturbed sampling. Drilling of five numbers of drill holes at predetermined locations was carried out. Various field tests such as permeability by Packer method (single and double Packer), open end permeability tests and extracting of core recovery to ascertain RQD value were carried out in all the drill holes to ascertain feasibility of foundation materials for constructing dam. Geotechnical challenges have been discussed in present paper during foundation investigations such as drilling in thick overburden in matrix materials at dam axis, Packer tests in fractured rocks and also extracting of rock core. It was concluded from Field permeability and RQD values that the foundation consisted of fractured rock with semi-pervious nature.

The construction of Deep Foundations has been in practice in India for several years and state of art design and construction techniques are being followed by practicing engineers for design of reinforced concrete and steel piles—both driven and bored. However, the quality control check of these underground structures is still in development stages and several destructive, partially destructive, and non-destructive tests are in various stages of developed and experiment. This paper presents an experimental study to determine the quality of piles based on non-destructive methods—low-strain pulse echo method and cross-hole sonic logging method. These two methods have recently gained wide acceptance as quality control procedure for piles in India being not only cost effective, but also provide reliable near accurate results if analyzed properly. To study the quality of piles, two bored reinforced concrete piles have been cast at proximate location using same construction techniques; one without any defect and one with known defects at known locations; and an attempt has been made to find the known defect with use of non-destructive tests. The paper discusses findings of two testing methods (low-strain pulse echo and cross-hole sonic logging) in detail and presents the effectiveness, analyzing techniques, and limitations of both the methods.

This paper presents a method for selecting and processing the field data for correlation and comparison of standard penetration test—cone penetration test (SPT-CPT). The correlations of SPT-CPT were done using traditional and statistical methods. SPT, CPT field tests were used in conjunction with variety of borehole seismic testing for a number of locations to adapt traditional site research approaches to geotechnical earthquake engineering. The correlations between N60 of SPT and cone tip resistance qc and other parameters of CPT data under liquefaction conditions were developed using regression modeling. In this paper, the SPT-CPT correlations have been developed using different type of regression methods, namely linear regression (LR), locally estimated scatterplot smoothing (LOESS), multivariate adaptive regression splines (MARS), and support vector machine (SVM). Correlation between N60 and qc which was developed using support vector regression (SVR) model is giving 90.53% efficiency. Correlation which was developed between N60 and qc taking other parameters of CPT data such as fines content and mean particle size D50 in SVR model is giving 99.99% efficiency. By using the above correlations, SPT N-value may be evaluated using CPT data. Predicted N60 values from these correlations are compared to measured N60 values from existing literature and seismic tests and it was found to be good.

The use of weathered airfall tephra deposits for geotechnical applications such as backfilling in embankments or foundations requires investigation. As a part of an experimental laboratory investigation addressing this issue, this paper focuses on the monotonic shear strength evaluation under drained and undrained shearing conditions of three airfall tephra deposits—namely Kaharoa (white–grey and golden brown) and Maungataketake (black-grey) ashes belonging to New Zealand. The shear strength results include tephra samples compacted at 90% degree of compaction. It is found that the geotechnical characteristics of such tephra deposits generally varied with the mode of deposition, resulting particle sizing and mineralogy of the tephra deposits. For instance, the white–grey Kaharoa tephra (closer to the vent) is primarily a granular material showing a dilative response (i.e., increases in volume in drained conditions and generates negative pore pressure in undrained conditions) and higher friction angle (ϕe ≈ 38–43°) at the end of test; on the other hand, the golden Kaharoa and black-grey Maungataketake ashes are comparatively fine-grained materials (away from the vent and reworked) showing a contractive response (i.e., decrease in volume in drained conditions and generate positive pore pressure in undrained conditions) and possess lower friction angles (ϕe ≈ 34–36°). The obtained friction angles 34–43° of the tephras are comparable or even greater than those of hard grained sands (ϕ ≈ 30°) making them applicable for geotechnical applications. Under large strain levels, the specimens seemed to be approaching critical or steady state of deformation, with breakage of particles during shearing and progression towards less resistant soil structure allowing deformations at constant shear stresses.

To perform the microzonation, site characterization and site response analysis play a crucial role. The sites can be efficiently characterized only when the basic parameters are correctly estimated. The 5 sites are selected in IIT (ISM) Dhanbad, Jharkhand, and the data is recorded using microtremor and this data is recorded in the summer and monsoon seasons of the year (2021). The authors have tried to record the data with less amount of anthropogenic noise. The five seismic parameters are comparatively computed, shear wave velocity (Vs), predominant frequency (f0), compressional wave velocity (Vp), H/V ratio, Poisson’s ratio, and the phase velocity of Rayleigh waves. The drastic variations in these parameters are observed for the upper portion of the ground, so the results can affect the seismic hazard analysis. The H/V ratio is higher in monsoon with a shift in f0. The variation in Vs is also drastically reduced (up to 10 m) during monsoon and Vp varies slightly increases, which results in the increase in Poisson’s ratio. This study may have a broader field of applications like in geotechnical and agricultural engineering projects.

Design of foundation, an important role for any major civil engineering structures viz. Nuclear and Thermal Power Plants, bridges, dams, barrages, etc., involves geotechnical investigations for determining detailed subsurface information; site characterization and damping characteristics of soil/ rock, etc. Borehole geophysical logging, compliment and supplement to geotechnical investigations, provide in-situ properties of subsurface lithology in a rapid, non-destructive and cost-effective way. Purpose of the paper is to highlight importance of borehole logging like nuclear, sonic and electrical logs in foundation studies for determining in-situ density, compressional wave velocities (Vp), shear wave velocities (Vs) and subsurface resistivity for identifying depth and quality of bed rock, different subsurface layers or strata, presence of liquefaction zone, Low Velocity Layer (LVL) and structural discrepancy, i.e. cracks, fracture and fault zone/shear zone, etc. and also calculating dynamic elastic properties of subsurface lithology, important for design-foundation of important civil structures. This paper is enlightened with different case studies where CW&PRS, Pune was deeply involved in design-foundation of important civil structures like Nuclear and Thermal Power Plants, jetties, etc. by providing subsurface geophysical and geotechnical information using land and underwater borehole logging. Discussion on importance of borehole geophysical logging in foundation studies in this paper may be useful to geotechnical engineers and professionals dealing with design-foundation of important civil structures.

Geotechnical investigation, site characterization and assessment of foundation rock play a vital role in design of foundation for any major important civil engineering structures viz. Nuclear and Thermal Power Plants, bridges, dams, etc. Geophysical techniques, complement and supplement to geotechnical investigations, provide compressional and shear wave velocities (i.e. Vp and Vs) of the subsurface layers in rapid and cost-effective way, using seismic method. Acoustic velocity (Vp and Vs) versus depth provides detailed picture of the subsurface. As ratio of Vp and Vs (i.e. Vp/Vs) is better indicator of lithology than individual velocity values i.e. Vp and Vs, objective of this paper is to highlight nature and behaviour of Vp/Vs and Poisson’s ratio, calculated using Vp/Vs, within near-surface layer and rock under different geological and structural condition, useful in characterization of subsurface. Vp/Vs and poison’s ratio, used in this paper, was calculated using digitized value of Vp and Vs w.r.t depth from real-time examples, selected on the basis of literature survey where cross-hole seismic survey was conducted prior to the foundation of critical civil structures. The discussion on subsurface characterization and assessment of foundation rock using Vp/Vs and Poisson’s ratio in this paper may be useful to geotechnical engineers and professionals dealing with design-foundation of important civil engineering structures.