Murali Krishna Adapa

Bio: Murali Krishna Adapa is an academic researcher from Indian Institute of Technology Guwahati. The author has contributed to research in topics: Finite element method & Caisson. The author has an hindex of 2, co-authored 6 publications receiving 17 citations. Previous affiliations of Murali Krishna Adapa include Indian Institutes of Technology & University of Surrey.

Experimental Investigation of Applicability of Sand Tire Chip Mixtures as Retaining Wall Backfill

Abstract: This paper explains the behavior of a cantilever retaining wall (CRW) backfilled with light weight fill material through small scale model wall tests. CRW model of height 60 cm and base width 50 cm was built with hollow aluminum sections. The model wall was installed in a Perspex container, tested under static and seismic loading conditions. Waste tire chips of 1 cm square cross section and 20 mm length mixed with the cohesionless sand in 5%, 10%, and 15% by weight were used as light weight backfill material. Concrete cubes were used as surcharge loading on the backfill during static testing. The lateral wall movements along the height of the wall were monitored during tests using displacement transformers. 1g shaking table tests have been conducted on the selective models to check the behavior of the cantilever wall under seismic loading conditions. It has been observed that the inclusion of tire chips in the backfill soil has led to the reduction of lateral wall movements due to the lesser unit weight of the mixtures. The reduction in the acceleration of the backfill was also observed during seismic testing in sand-tire chip (S-TC) backfill compared to the controlled case (only sand).

Seismic resilience of retaining walls backfilled with sand–tire chips mixtures

Abstract: Seismic resilience of retaining wall with different sand – tire chips (STC) mixtures as backfill materials has been investigated. This paper presents the results of 1g-shaking table model tests carried out on retaining wall models of 600 mm height backfilled with different proportions of STC mixtures. The test program used two types of scaled earthquake input motions: Sikkim and South Napa. Model walls behaviours are presented in terms of incremental earth pressures acting on the wall and the associated displacements, as well as the accelerations at various locations of the model wall. Physical model test results revealed that the seismic incremental earth pressures, wall displacements, and accelerations were significantly reduced by using STC mixtures as backfill materials. Based on experimental model results, STC mixture backfills showed higher seismic resilience behavior compared to that of with conventional sand backfill.

Simplified Methodology for Stiffness Estimation of Double D Shaped Caisson Foundations

Abstract: Foundation stiffness plays a crucial role in the stability analysis of structures to incorporate the Soil Structure Interaction (SSI) effects Current design approaches of estimating foundation stiffness include advanced dynamic finite element, distributed spring approach, and lumped spring approach The aim of this paper is to overview the different methods for computing the foundation stiffness and to check their applicability This has been done by considering an example: Saraighat Bridge supported on double D shaped caisson foundation Advanced three dimensional finite element analysis is performed to extract the stiffness (Lateral, rotational, and coupling) of double D foundations and the results are compared to the representative circular foundations It has been concluded that the stiffness of foundation can be significantly affected by its geometry Furthermore, the stiffness functions are utilized in computing the fundamental frequency of the bridge and also compared with the frequency obtained from different approaches The frequency estimated using the present study matches satisfactorily well with the monitored data testifying the validation of the work

Characterization of Ground Response and Liquefaction for Kathmandu City Based on 2015 Earthquake Using Total Stress and Effective Stress Approach

Abstract: This chapter presents the seismic vulnerability of Kathmandu City (Nepal), based on Nepal 2015 earthquake, in terms of the ground response and liquefaction potential. The spatially well-distributed 10-boreholes and ground motions of Mw 7.8 Nepal 2015 earthquake recorded at five different stations were adopted for the analysis. The range of peak ground acceleration and peak spectral acceleration were in the order of 0.21g-0.42g and 0.74g-1.50g, respectively. Liquefaction potential of the sites were computed using both semi-empirical approach and liquefaction potential index (LPI). LPI shows that the 6 sites out of 10 sites are at high risk of liquefaction.

Prediction of Ground Settlement Induced by Slurry Shield Tunnelling in Granular Soils

Abstract: Underground structures play an important role in achieving the requirements of rapid urban development such as tunnels, parking garages, facilities, etc. To achieve what is needed, new transportation methods have been proposed to solve traffic congestion problems by using of high-speed railway and subway tunnels. One of the issues in urban spaces due to tunnel excavation is considerable surface settlements that also induce problems for surface structures. There are a variety of published relationships concerned with field measurements and theoretical approaches to evaluating the amount of the maximum surface settlement value due to tunneling. This paper studies the ground surface settlement caused by the Greater Cairo Metro – Line 3 - Phase-1. This project was constructed by a slurry shield Tunnel Boring Machine (TBM). Therefore, this work consists of two parts. The first part presents the details of the project and monitoring results field and laboratory geotechnical investigations in order to determine the soil properties. The second part is to the comparison between the field measurements and theoretical approaches for surface settlement due to tunneling construction. At the end of the works, the results show that the more convenient methods which approach the field measurements, and the major transverse settlement occurs within the area about 2.6 times the diameter of the tunnel excavation. Doi: 10.28991/cej-2020-03091617 Full Text: PDF

Sustainable Utilization of Scrap Tire Derived Geomaterials for Geotechnical Applications

Abstract: Use of scrap tire derived (STD) geomaterials in geotechnical engineering applications has received growing interest to prevent creation of wastes and conserve natural resources towards achieving sustainability. STD geomaterials and their mixtures with soils are being used in highway embankments, retaining walls, landfills and other applications as lightweight fill, backfill, compressible inclusion, vibration absorber, and drainage material. The use of STD geomaterials in these applications has been affirmed by characterization of the engineering properties based on laboratory tests and performance assessment based on physical model studies. This paper provides a review of engineering properties of STD geomaterials and their mixtures with soil (predominantly sand) based on published studies. Further, laboratory model and field studies on typical applications of STD geomaterials/mixtures such as retaining walls, foundations, embankments, and landfills are discussed. Overall, STD geomaterial alone or sand mixed with optimal STD content of 30–40% by weight has been shown to be effective for geoengineering applications.

Tyre chips as compressible inclusions in earth-retaining walls

Abstract: This paper investigates the performance of retaining wall models using recycled tyre chips as compressible inclusions under dynamic loading through shaking table tests. Scrap tyre derived tyre chips of 10 × 10 mm size and about 20 mm length have been used in this study. The 600 mm high model wall is constructed in a poly(methyl methacrylate) (PMMA) container and instrumented with pressure sensors, displacement transducers and accelerometers at different locations. The dynamic responses of the retaining walls to the variations in the acceleration and frequency of base shaking are monitored and discussed. It is observed from these tests results that the horizontal displacement and incremental lateral earth pressure responses of the retaining wall models are significantly reduced by the inclusion of the tyre chips. Reduction of the lateral earth pressure and displacement makes possible lower design requirements that entail smaller dimensions of the retaining wall with reduced material cost.

Sand–scrap tyre chip mixtures for improving the dynamic behaviour of retaining walls

Abstract: This paper presents the dynamic response of retaining wall models backfilled with different types of sand–tyre chips (STC) mixtures using shaking table tests. The STC mixtures with different tyre c...

2D numerical analysis of a cantilever retaining wall backfilled with sand–tire chips mixtures

Abstract: Previous research has shown that the backfill behind a retaining wall can be constructed with sand–tire chips (STC) mixture; this can lead to reduced horizontal displacements and earth pressures on...