Sometimes a pavement deflects only because of seasonal volume change of expansive soils in the pa... more Sometimes a pavement deflects only because of seasonal volume change of expansive soils in the pavement subgrade. Engineering practitioners expect an implementable and straightforward analysis method for a geosynthetic-reinforced pavement subjected to the swelling/shrinkage issue of expansive clayey subgrade, in an effort to find the bending moment, shear force and tension force distributions through the reinforced pavement, which are induced from the volumetric changes of subgrade soils. The virtual load method (VLM) was proposed in the past following the Timoshenko beam theory to analyze geosynthetic-reinforced pavement on expansive soils. In the VLM, the unknown virtual distributed load was obtained in the way by applying the inverse theory for the identification of material parameters of the pavementfoundation system. It was seen that the selection of the number of material parameters to obtain virtual load significantly affects the accuracy of the structural properties of the pavement and tensile properties of the geosynthetics if the linear least square method is used. In this paper, a unique numerical scheme was proposed in the hopes of solving the issue. After a forward problem was solved numerically, the Timoshenko beam deflection was taken as a start-up for the inverse problem to back analyze the load applied to the pavement. Solutions from forward/backward examples have explicitly shown the accuracy achieved related to the bending moment in the pavement and tension in the geosynthetic reinforcements. The proposed methodology can be applied for an in-depth understanding of the geosynthetic function for the mitigation of longitudinal cracks on pavements caused by heave/shrinkage of expansive soils.
Experimental Study on Soil–Water Retention Properties of Compacted Expansive Clay
Lecture notes in civil engineering, Sep 17, 2021
The soil–water characteristic curve (SWCC) defines the relationship between water content and mat... more The soil–water characteristic curve (SWCC) defines the relationship between water content and matric suction in soil, which contains fundamental information needed for the hydromechanical behavior of expansive soil that generally lies within the unsaturated soil mechanics framework. Moreland clay is highly expansive soil abundant in northern Louisiana, part of Arkansas, and Oklahoma. Unsaturated soil properties for shear strength, permeability, and volume change are needed to identify expansive soil-induced stresses on pavement or railroad track due to seasonal variation of moisture content in the subgrade layers. Determination of the two critical variables obtained from the SWCC, i.e., the air-entry value (AEV) and the residual state suction, is essential for the prediction of unsaturated soil deformations. In this research, an experimental testing program was conducted on the expansive Moreland clay to investigate the soil–water retention properties by adopting the axis translation technique to control suction in the range of 0–1500 kPa. A computer program was developed to fit experimental data, and it was compared with predicted SWCC using empirical relationships. The AEV and the residual state suction, two critical variables, were obtained from the SWCC formulation of Fredlund and Xing equation. Finally, the shrinkage curve was determined to interrelate between elastic deformation and SWCC of Moreland clay.
Engineering, Technology & Applied Science Research, Jun 2, 2023
Wastewater is a byproduct of industrial or household waste processes, and its contamination level... more Wastewater is a byproduct of industrial or household waste processes, and its contamination level must be determined before treatment. Discharges of liquid effluents generated by mining operations, one of the most prevalent forms of industrial waste water, pose a risk to human health and the environment. This study evaluates the physicochemical quality of industrial liquid effluent discharges from the Boukhadra mine (Algeria). Samples were collected from the washing water to identify the level of contamination of these liquid discharges and to measure physicochemical parameters such as temperature (T), hydrogen potential (pH), Electrical Conductivity (EC), Suspended Solids (SS), Chemical Oxygen Demand (COD), Biological Oxygen Demand for 5 days (BOD5), Oils and Greases (O&G), iron (Fe +2) and Kjeldahl Nitrogen (NTK). It was found that the concentration values of those effluents exceeded the maximum contamination limits specified by international industrial waste standards. A simple and reliable prediction model was developed to estimate DBO5, based on MES, COD, and O&G, by using classical regression analysis and fitting Design of Experiments (DOE) methodology. When comparing the analytical results, it was found that the quadratic model provided a better estimation, with a high correlation coefficient (R 2) of 0.9976. The parameters determined in this study will enable engineers to quickly estimate the degree of wastewater contamination and choose adequate treatment strategies.
Engineering, Technology & Applied Science Research
Wastewater is a byproduct of industrial or household waste processes, and its contamination level... more Wastewater is a byproduct of industrial or household waste processes, and its contamination level must be determined before treatment. Discharges of liquid effluents generated by mining operations, one of the most prevalent forms of industrial waste water, pose a risk to human health and the environment. This study evaluates the physicochemical quality of industrial liquid effluent discharges from the Boukhadra mine (Algeria). Samples were collected from the washing water to identify the level of contamination of these liquid discharges and to measure physicochemical parameters such as temperature (T), hydrogen potential (pH), Electrical Conductivity (EC), Suspended Solids (SS), Chemical Oxygen Demand (COD), Biological Oxygen Demand for 5 days (BOD5), Oils and Greases (O&G), iron (Fe+2) and Kjeldahl Nitrogen (NTK). It was found that the concentration values of those effluents exceeded the maximum contamination limits specified by international industrial waste standards. A simple an...
Development of a Mechanistic-based Design Method for Geosynthetic-Reinforced Pavement on Expansive Soils and Prediction of Moisture Content Fluctuations in Subgrades
Sometimes a pavement deflects only because of seasonal volume change of expansive soils in the pa... more Sometimes a pavement deflects only because of seasonal volume change of expansive soils in the pavement subgrade. Engineering practitioners expect an implementable and straightforward analysis method for a geosynthetic-reinforced pavement subjected to the swelling/shrinkage issue of expansive clayey subgrade, in an effort to find the bending moment, shear force and tension force distributions through the reinforced pavement, which are induced from the volumetric changes of subgrade soils. The virtual load method (VLM) was proposed in the past following the Timoshenko beam theory to analyze geosynthetic-reinforced pavement on expansive soils. In the VLM, the unknown virtual distributed load was obtained in the way by applying the inverse theory for the identification of material parameters of the pavement-foundation system. It was seen that the selection of the number of material parameters to obtain virtual load significantly affects the accuracy of the structural properties of the ...
Experimental Study on Soil–Water Retention Properties of Compacted Expansive Clay
The soil–water characteristic curve (SWCC) defines the relationship between water content and mat... more The soil–water characteristic curve (SWCC) defines the relationship between water content and matric suction in soil, which contains fundamental information needed for the hydromechanical behavior of expansive soil that generally lies within the unsaturated soil mechanics framework. Moreland clay is highly expansive soil abundant in northern Louisiana, part of Arkansas, and Oklahoma. Unsaturated soil properties for shear strength, permeability, and volume change are needed to identify expansive soil-induced stresses on pavement or railroad track due to seasonal variation of moisture content in the subgrade layers. Determination of the two critical variables obtained from the SWCC, i.e., the air-entry value (AEV) and the residual state suction, is essential for the prediction of unsaturated soil deformations. In this research, an experimental testing program was conducted on the expansive Moreland clay to investigate the soil–water retention properties by adopting the axis translatio...
Development of a Mechanistic-based Design Method for Geosynthetic-Reinforced Pavement on Expansive Soils and Prediction of Moisture Content Fluctuations in Subgrades
In this paper, numerical analysis is carried out to identify borehole log at a particular locatio... more In this paper, numerical analysis is carried out to identify borehole log at a particular location of a site thus producing a number of parameters which are empirically related to SPT values. The Standard Penetration Test (SPT) remains the most common site investigation tool used throughout the world. Physical properties of soil are found by correlations with values of recommended standard N 60 , determined in SPT tests. Janjira Approach road of ongoing Padma Multipurpose Bridge Project was considered for this study to collect 15 borehole log along 20 km stretch. Disturbed soil sample were collected up to 19.5m depth in every 1.5m interval to perform Sieve-analysis test. Spreadsheet was used to input of over 600 data including SPT-N values, Percent Sand & Percent Fines at depths, Reduce Level & Ground Water Table at different Chainage locations. By using all these data-a mathematical model was developed in MATLAB, a high-level language and interactive environment for numerical computation, visualization, and programming. Rectangular grids in multidimensional space were created for Interpolation and/or Extrapolation for 2-D and/or 3-D gridded data in 'meshgrid' format. The purposes of the study are to find vertical SPT profile & soil-profile in a particular alignment of the site and to extract borehole log form SPT profile & soil-profile at intermittent locations of that alignment. SPT profile is presented graphically using contour plot of matrix and soil-profile is presented by 3-D shaded surface plots. Predicted borehole log could be useful for preliminary selection of a project site, land use planning, zoning ordinances, pre-disaster planning, and capital investment planning. Seismic soil liquefaction was evaluated for this site in terms of the factors of safety against liquefaction (FS) along the depths of soil profiles for different peak ground acceleration ranging 0.3g to 0.45g and earthquake magnitude ranging 6 to 7.5 on Richter scale. Cyclic Strength Ratio (CSR) and Cyclic Resistance Ratio (CRR) was determined with 10 % probability of exceedance in 50 year using SPT-based simplified empirical procedure. Liquefaction potential index (LPI) is evaluated at borehole locations from the obtained factors of safety (FS) to assess the potential of liquefaction to cause damage at the surface level at the site of interest. To validate the model, recent occurred Nepal Earthquake was taken as an example to compare the level of liquefaction severity assessed by in-situ and predicted borehole log data.
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Papers by Debojit Sarker