Investigation of rock mass destruction during mining

Problems of stress-strain states of a rock mass during coal exploitation by using the method of longwalling are still assessed prevailingly on the basis of the classification of rocks occurring in the effective hanging wall of the seam. It has been proved that it is also the main roof mainly reaching as far as the previously worked out seam that affects these problems. Determining the stress state of the rock mass exploited is very difficult and the majority of methods are considerably expensive. One of the methods that we may use in the assessment of development of deformation, and thus the state of stress intherockmass, is observing the formation of a subsidence trough on the surface in time. Paper deals, on the basis of measurements of the formation of a subsidence trough in time and in dependence on mining geometry.