Effect of discontinuities on strata-movement problems in collieries: a review

SummaryThe influence of discontinuities on coal measures is manifested in the form of roof and side falls, caving of the roof and sometimes in subsidence of the ground surface. This review paper is confined to roof falls due to major geological discontinuities (such as faults, joints, cleats and bedding planes) and to possible ways and means to prevent these falls. Faults with an increased frequency of joints and cleats around them, slips and slickensides play a major role in coal-mine-roof instability. Joints and cleats running parallel to roadways and thinly bedded strata in the immediate roof area also contribute to strata-instability problems. A roof-fall index has been developed relating roof instability to the presence of geological discontinuities. Significant control of such instabilities is possible by orienting roadways across the geological discontinuities and by increasing the quality and density of the supports.

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