Yermakov V. Forecasting the modification of underworked rock mass condition due to abandonment of coal mines

Object of research - rock massif at coal mines shutdown. The purpose of research - development of a method for forecasting surface deformations and yielding above shutdown mines fields based on the account of rocks physic-mechanical properties changing at them wetting and activation of geomechanical processes in rock massif above the goaf. Methods of research - complex method of researches including: study of hydro-geological and geomechanical processes at steep seams working-off in the CRD, including, also, a period of the mining shutdown; an experimental research of the rock physic-mechanical properties at there humidity changing; generalization and analysis of the rock pressure operating ways influence. Researching of branch techniques of rock massif physic-mechanical processes and deformation processes studying, with application of mathematical statistics methods. Theoretical results and the novelty - For the first time is established, that at water-saturation process of rocks and coals, at small c hange of their volumetric strength occurs significant (more than in 2 times) reduction of crack resistance. It takes to sharp losing of pillar stability; is established, that as a result of reduction of rock strength and their plasticization at wetting, the process of a roof failure upon the goaf most activates at the ways of rock pressure operating "deduction on fires" and at a shield robbing, what will cause renewal of rock massif and surface deformations; is established, that the period of geomechanical processes attenuation in a rock massif and at surface in a time of robbing of CRD steep coal seams assise, amount 7-10 years. Practical results and the novelty - consists in using of the methods of rock massif condition analysis at coal mines shutdown, for the forecast of geomechanical processes. Subject and degree of introduction - the Basic results is used at drawing up of the Ministry of Coal Industry branch normative document. Range of application is intended at mines and R&D institutes of Ministry of C oal Industry and N.A.S. of Ukraine.