ABSTRACT
The stability of pit slopes with haul roads is endangered by movement of machinery also in addition to other risk factors. Presence of old underground workings or caverns in the rockmass adds to the complexity of the problem. Stability of slopes over old underground workings in Jharia Coalfield, India is investigated. Equivalent material modelling technique is adopted for better simulation of the situation and physical observance of failure phase. The failure mechanism of rise slope is found as translatory-cum-toppling, whereas that of dip slope as span-cum-toppling. Development of a tension crack behind the crest and its progressive widening in a scissor like manner are indications of a toppling movement. The consequent toppling of the haul roads can be avoided by advancing the top portion of the slope beyond the zone of influence of the void. Afterwards, the lower portion of the slope housing void can be worked by collapsing the parting over the void and compacting it with extra fill. Thereafter, the equipment can ply on the stabilized ground.
