Exploration of subsurface strata conditions for a limestone mining area in India with ground-penetrating radar

Abstract

A study has been conducted for the exploration of underground voids and strata conditions at shallow depth in a limestone mine of Manikgarh Cement at Maharashtra in India. The Manikgarh Cement is surrounded with high-quality limestone having platy formations with excessive fractures and fissures. A perennial river, the Amal Nala, is flowing across the middle of limestone mining lease of the Manikgarh Cement Captive Mine. The impact of this water body on the mining is the central theme of this study. Excavation of limestone is in progress in different blocks on both sides of the Amal Nala. For the purpose of planning it was necessary to know the ground conditions of the area surrounding the Amal Nala so that seepage of the water can be checked. If there is no adverse impact due to deepening of mining activity, the minerals lying at depth can be safely exploited. A ground-penetrating radar (GPR) survey was carried out in the mining lease area to investigate the condition of the strata (status of fractures, cracks, cavities, etc., through which seepage or water percolation takes place). The results of this survey reveal that solid compact layers exist from the surface to depths varying from 2 to 5 m only along the three sections G1G1, G2G2 and G3G3 (lying in the mining area of the Manikgarh limestone along both sides of the Amal Nala). Fractured/weathered rocks and solution cavities exist from the surface to depths varying from 4 to 16.5 m. Therefore, extraction of limestone is possible only to depths of 2 to 5 m from the surface in this mining area. If extraction continues below this depth, the seepage of water from the Amal Nala will start due to the presence of enormous fractures and cavities (solution holes) in the underlying limestone strata. In addition, the water of the Amal Nala will be disturbed, which is the main water reservoir of this area.