A Laboratory Study on Estimation of Shear Strength and Compaction Properties of Overburden Dump Material in Indian Coal Mines

Abstract

The study investigates the effect of various soil mixtures, mostly found in the overburden material of coal mines, on the strength parameters and compaction properties. Samples were prepared in laboratory to represent both the soil-type and the rock-type waste dump material by mixing shale, sandstone and clay in varying proportions at an interval of 10% each. Samples from two coal mines located at different geographical locations in the eastern part of India were collected and the shear strength (cohesion and friction angle) and compaction parameters (Maximum dry density, MDD and Optimum moisture content, OMC) of the specimens were determined from laboratory study at moisture content around their OMC and analysed. The results so establish that the shear strength parameters for mixtures containing shale are less sensitive to changes and follows rather a flat curve when plotted against their respective material content in the mixture when compared to that containing clay. However, the compaction parameters were found to follow different trends when plotted against the constituent material (shale, sandstone and clay) content of the mixture.

A Porosity-Height Relationship for Soil-Rock Mixtures of Unsaturated Dumps Based on Field and Laboratory Investigations

“…Oggeri et al [14] highlighted that assessing compaction properties is essential for characterizing S-RM of dump slopes for better equipment selection, which optimizes the handling of overburden. An analysis of the compaction properties of soil mixtures, including shale, sandstone, and clay, indicated strong connections between the amount of shale and the maximum dry density achieved in the laboratory by Bishwal et al [15]. Porosity measurements of sand-clay mixtures were investigated by Vallejo & Mawby [16] with increasing levels of compaction.…”