Shubham A. Kalore

Bio: Shubham A. Kalore is an academic researcher from Indian Institute of Science. The author has contributed to research in topics: Geotechnical engineering & Hydraulic conductivity. The author has an hindex of 1, co-authored 5 publications receiving 8 citations.

Design approach for drainage layer in pavement subsurface drainage system considering unsaturated characteristics

Abstract: Providing adequate subsurface drainage feature in a pavement system to remove the infiltrated moisture in a minimum time is an important design consideration, which prevents the premature failure of the pavement system, and hence helps in achieving a significantly lower life-cycle cost. Various surface drainage measures are taken to minimize the ingress of moisture into the pavement gradually lose their efficiency with the aging of the pavement. The use of an appropriate open-graded aggregate course as a drainage layer in the pavement is the best way to minimize the time for which the pavement materials are exposed to saturated conditions. The current drainage guidelines have been developed on the basis of moisture flow under saturated condition. A better understanding and estimation of moisture movement in a drainage layer can only be achieved by using seepage analysis that adopts the principles of saturated as well as unsaturated flow conditions. State-of-art of mathematical tools such as finite difference and FEA methods permits a rigorous solution of Richard’s equation for saturated and unsaturated moisture flow in a porous medium, the only major drawback is the need for rigorous modeling and computational tool for the simulations and the design of the drainage layer. This paper focuses on the development of an analytical model for estimating the time to drain considering the unsaturated characteristics of pavement base material and calibration of the developed model based on a mechanistic approach which is relatively inexpensive. The applicability of the approach is explained by using the four-standard aggregate gradations recommended by AASHTO for the drainage layer, as well as a dense graded aggregate layer, and the results are compared with those from the FHWA approach and finite element analysis. The study shows that the developed model performs as good as the finite element analysis, which requires rigorous numerical modeling, predicts drainage times that are significantly different from those obtained from the FHWA analysis, and that it is sensitive to key significant design parameters. Hence, the proposed model is recommended for regular use for the design of the drainage layer and for a parametric study of the complete drainage process.

Hydraulic conductivity requirement of granular and geotextile filter for internally stable soils

Abstract: A filter media satisfying the hydraulic conductivity requirements allows unimpeded seepage without generation of surplus pressure head and decrease of flow rate. This paper proposes design criteria for the hydraulic conductivity requirements of a filter based on governing flow equations. The results have shown that the hydraulic conductivity requirements of pressure head and flow rate are satisfied with a single condition of hydraulic conductivity of filter greater than or equal to the hydraulic conductivity of soil times the hydraulic gradient in soil. The proposed model is developed for saturated conditions and is also applicable for partially saturated conditions. The developed model is validated based on the experimental evaluations of sandy soil with three granular filters and two needle punched non-woven geotextile filters. The developed design criterion applies to internally stable soils with granular and geotextiles filters and offers an improvement in the standards and current design guidelines for protective filters.

Probabilistic Design Framework for Granular Filters

Abstract: A granular filter is required to satisfy two requirements of retention and hydraulic conductivity. The current design approaches are based on the representative grain sizes for retention an...

Improved design criteria for nonwoven geotextile filters with internally stable and unstable soils

Abstract: In geotextile filtration, the soil fines are either accumulated near the interface, clogged, or washed out, which primarily depends on the grain size distribution (GSD) of soil and the constriction size distribution (CSD) of geotextile. Also, the movement of fines significantly affects the flow capacity of geotextile. Currently, the retention requirement is satisfied based on representative grain and opening sizes, whereas the hydraulic conductivity and clogging requirements are satisfied considering the properties of virgin geotextile. This paper presents a probabilistic retention criterion considering the grain and constriction sizes as random variables. The influence of geotextile thickness is incorporated into the criterion by considering the number of geotextile constrictions in a filtration path. A theoretical approach to predict CSD is presented if the measured data is unavailable. For hydraulic conductivity and clogging requirements, a criterion is presented considering the expected partial clogging of geotextile, which is predicted based on the semi-analytical approach. The limit states for the developed criteria are evaluated based on the wide range of experimental data from the current study and published literature. The developed design criteria are applicable to internally stable and unstable soils, which offers an improvement in design compared to the existing criteria in practice.

Approach to Estimate Hydraulic Conductivity Function from Soil–Water Retention Curve for Noncohesive Soils

Abstract: Pavement materials are prone to damage due to mechanical loadings and rainfall infiltration. The rainfall initiates moisture movement within the layers and accelerates the damaging rate. A ...

Assessment of permeability of granular drainage layer considering particle size and air void distribution

Abstract: Granular drainage layers are utilized in the permeable pavement structure to temporarily store the infiltrated water and to gradually penetrate it into the underlying layer or the subsurface drainage system. The selected particle size distribution (PSD) of aggregate and consequently the size of air voids distributed between particles inherently affect the drainage capability of drainage course. In the present study, the effect of distribution of pores between aggregate along with the general properties of characterized gradation curve on the permeability of this granular porous media is assessed by establishment of various PSDs. For this purpose, large-scale constant head permeability test is carried out on distinct gradations of coarse-sized aggregate derived from three different rock types. A well-established analytical procedure is utilized to determine the constriction size distribution characterizing the interconnectivity of pores. A probabilistic approach is employed to estimate the distribution of size of air voids based on the captured two-dimensional images from prepared specimens. Obtained results confirm nonlinear relationship between the flow velocity and the applied hydraulic gradient especially for specimens comprised of more uniform size range. Also, the developed relationship based on the power law between the hydraulic conductivity and the characteristic pore size can effectively describe the permeability of coarse-sized aggregate used as drainage layer. Furthermore, establishment of gradation with higher uniformity coefficient leads to smaller-sized pores between particles and consequently lower hydraulic conductivity coefficient. Finally, the extended regression model based on the characterized properties can effectively predict the permeability of aggregate specimen.

Hydraulic conductivity requirement of granular and geotextile filter for internally stable soils

Abstract: A filter media satisfying the hydraulic conductivity requirements allows unimpeded seepage without generation of surplus pressure head and decrease of flow rate. This paper proposes design criteria for the hydraulic conductivity requirements of a filter based on governing flow equations. The results have shown that the hydraulic conductivity requirements of pressure head and flow rate are satisfied with a single condition of hydraulic conductivity of filter greater than or equal to the hydraulic conductivity of soil times the hydraulic gradient in soil. The proposed model is developed for saturated conditions and is also applicable for partially saturated conditions. The developed model is validated based on the experimental evaluations of sandy soil with three granular filters and two needle punched non-woven geotextile filters. The developed design criterion applies to internally stable soils with granular and geotextiles filters and offers an improvement in the standards and current design guidelines for protective filters.

Probabilistic Design Framework for Granular Filters

Abstract: A granular filter is required to satisfy two requirements of retention and hydraulic conductivity. The current design approaches are based on the representative grain sizes for retention an...

Water Distribution Influenced by Pavement Alignment Design

Abstract: To obtain the water distribution influenced by pavement alignment design under the current situation of highway reconstruction and extension in China, a simulation model for predicting pave...

Improved design criteria for nonwoven geotextile filters with internally stable and unstable soils

Abstract: In geotextile filtration, the soil fines are either accumulated near the interface, clogged, or washed out, which primarily depends on the grain size distribution (GSD) of soil and the constriction size distribution (CSD) of geotextile. Also, the movement of fines significantly affects the flow capacity of geotextile. Currently, the retention requirement is satisfied based on representative grain and opening sizes, whereas the hydraulic conductivity and clogging requirements are satisfied considering the properties of virgin geotextile. This paper presents a probabilistic retention criterion considering the grain and constriction sizes as random variables. The influence of geotextile thickness is incorporated into the criterion by considering the number of geotextile constrictions in a filtration path. A theoretical approach to predict CSD is presented if the measured data is unavailable. For hydraulic conductivity and clogging requirements, a criterion is presented considering the expected partial clogging of geotextile, which is predicted based on the semi-analytical approach. The limit states for the developed criteria are evaluated based on the wide range of experimental data from the current study and published literature. The developed design criteria are applicable to internally stable and unstable soils, which offers an improvement in design compared to the existing criteria in practice.