RESEARCH INTEREST

 “Success doesn’t come from marks, grades, or distinction, it comes from experiences that expand your belief of: “What is possible”.


My basic interest and expertise lie in research in the geotechnical & geoenvironmental arena.

I am particularly interested in the following:

1. Waste Mechanics & Management

2. Landfill Engineering

3. Pile Foundation

4. Geotechnical Field Testing

5. Geophysical Testing

6. Groundwater contamination

7. Ground Improvement Techniques

8. Modeling Contamination Transport

Snapshot of Significant Research Contributions

Appropriate Method of Determination of Coefficient of Consolidation for Municipal Solid Waste 

To predict the rate of settlement of municipal solid waste specimens (MSW), it is essential to estimate the value of the coefficient of consolidation (Cv) using laboratory consolidation test results. Literature suggests that the various empirical curve-fitting methods used for assessing Cv is Casagrande’s logarithm of the time fitting method and Taylor’s square root of the time fitting method for the same test data. Both methods are derived from the time factor and degree of consolidation (T–U) relationship and corresponding laboratory time–compression (T–δ) relationship. For different types of wastes and loading conditions, the shapes of curves vary considerably, and the validity of these approaches is not established. In all these cases, the estimation of the Cv poses a serious problem. To overcome the above difficulties, the rectangular hyperbola method is used, in this article, to determine the Cv by U–T or t versus δ relationship. Earlier, this method was used for the different coefficient of consolidation values of time for completion of different percentages of consolidation. It is found that the calculated values of Cv are found to be more reliable when the time for 60 % of consolidation is taken. The estimated Cv values from the rectangular hyperbola method lie between the existing standard methods of Casagrande’s and Taylor’s. The rectangular hyperbola method is simple and can be used for all shapes of time–compression curves, and the specific advantage of this method is that the initial compression need not be known and is devised to separate the initial, primary, and secondary compression for any load increment.

Design, fabrication and calibration of a tall pneumatic oedometer apparatus

In conventional odometers, the height to diameter ratio of samples is kept small enough to minimize friction between the soil and cell walls. However, in oedometers with a higher height to diameter ratio, evaluating the effect of frictional interaction is imperative. This paper presents the development and experimental evaluation of a tall oedometer. Equipped with pore pressure transducers and lateral and normal pressure cells, this oedometer is capable of measuring pore pressure and lateral stresses. The tallness of the oedometer facilitates the evaluation of compressibility properties in highly compressible geomaterials. With the aid of the bottom load cell, the distribution of frictional stresses between the geomaterials and the walls can be measured. Experimental tests have been devised to obtain the actual vertical stress profiles, and results have been verified with analytical solutions in literature as well as numerical modeling. The experimental investigation illustrated the satisfactory performance of the equipment.

SOCIETY BASED RESEARCH:

Physico-chemical and biological characterization of urban municipal landfill leachate

Unscientific management and ad-hoc approaches in municipal solid waste management have led to a generation of voluminous leachate in urban conglomerates. Quantification, quality assessment, following treatment, and management of leachate has become a serious problem worldwide. In this context, the present study investigates the physicochemical and biological characterization of landfill leachate and nearby water sources and attempts to identify relationships between the key parameters together with understanding the various processes for chemical transformations. The analysis shows an intermediate leachate age (5e10 years) with higher nutrient levels of 10,000-12,000 mg/l and ~2000-3000 mg/l of carbon (COD) and nitrogen (TKN) respectively. Elemental analysis and underlying mechanisms reveal chemical precipitation and co-precipitation as the vital processes in leachate pond systems resulting in the accumulation of trace metals. Based on the above criteria the samples were clustered into major groups that showed a clear distinction between leachate and water bodies. The microbial analysis showed bacterial communities correlating with specific factors relevant to redox environments indicating a gradient in nature and abundance of biotic diversity with a change in leachate environment. Finally, the quality and the contamination potential of the samples were evaluated with the help of the leachate pollution index (LPI) and water quality index (WQI) analysis. The study helps in understanding the contamination potential of landfill leachate and establishes linkages between microbial communities and physicochemical parameters for effective management of landfill leachate

A study on contamination of ground and surface water bodies by leachate leakage from a landfill in Bangalore, India

This paper discusses the effects of a potential leachate leakage from a municipal solid waste landfill, situated at Mavallipura, Bangalore, India, on the surrounding water bodies. The landfill area is spread over an area of about 100 acres that began accepting waste in 2005. MSW was deposited in a non-engineered manner that has result in steep and unstable slopes, leachate accumulation within the MSW mass, and leachate runoff into nearby water bodies such as ponds and open wells. The current study investigates the physicochemical characterization of landfill leachate and nearby water bodies. The batch leach tests were conducted to know the heavy metal concentrations in the contaminated soil. A series of column tests were also conducted to estimate the migration rates of different contaminants through the soil. Furthermore, these transport parameters were considered as input for a fuidyn-POLLUSOL model to estimate the migration of leachate from the landfill site to the surrounding water bodies.

Fly ash bricks development using concrete waste debris and self‑healing bacteria

In this study, an effort has been made to use concrete waste debris for the manufacturing of fly ash bricks as a sustainable material. Though in earlier studies, attempts have been made to use concrete waste debris to manufacture fly ash bricks however it becomes inferior as mechanical properties in comparison to regular fly ash brick have always been a concern. To overcome the problem, self-healing bacteria (SHB) has been amalgamated in the manufacturing process. Various tests have been performed to evaluate the mechanical properties, microstructure, and morphology of four different compositions of brick samples. The study revealed that brick made with concrete debris and SHB was having mechanical properties at par with red clay brick with an initial rate of absorption of about 4.8 kg/m2/min, water absorption as 15.72%, and compressive strength of 10.29 MPa observed to be even higher than red clay bricks. Further X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) studies revealed the presence of lesser micro-cracks over the bricks structure made up of concrete debris and SHB in comparison to other samples. This investigation revealed that the use of SHB results in a higher strength with lesser void formation which helps in achieving higher performance quality parameters for brick manufacturing using concrete waste debris as sustainable materials.