Design of Dump Slope on Weak Foundation

Abstract

The present paper discusses the effect of weak foundation on dump stability and nearby structures such as roads. A case study of Indian coal mine has been taken for designing the dump on weak foundation. The top soil of the present study area is black cotton. Thickness of black cotton is varied from 2 to 10 m. Two-dimension numerical modeling has been done to analyze the effect of weak foundation on dump stability. Various Numerical models have been prepared by varying the thickness of weak foundation and with different remedial designs to optimize the dump design on weak foundation. The factor of safety is calculated by Strength Reduction Techniques. The maximum shear strain has been found in the foundation (black cotton clay). It indicates that failure initiated in foundation and it led to dump failure. Five different scenarios of models have been numerically simulated, i.e., (a) Dump material with weak foundation, (b) partial excavation of black cotton soil (c) full excavation of black cotton soil, (d) Excavation of black cotton soil around periphery of dump and (e) installing columns of dump material of varying width at constant distance of 10 m. It was found that strength of overburden dump can significantly enhanced without fully excavating weak soil, by using competent overburden material and it also affect heaving of weak soil. © 2022, The Institution of Engineers (India).