Site Stability Analysis For The Steep Coal Seam Old Goaf Urumqi City, Xinjiang

Underground coal mining make the overlying strata lose support, rock mass’s originalstress balance damaged, stresses in rock mass redistribute and the gob surrounding rock move,deform and damage. With the enlargement of the gob area, above surface will producedeformation. This will seriously affect the upper buildings foundation, and eventually lead todamage to buildings. In-depth and systematic research on Stability of mined-out areaoverlying strata is particularly important, because of the harmful effects of coal mining on thesurface cause great threat to people’s property and life safety.This paper is based on the data from the steep coal seam gob area in Urumqi, Xinjiangprovince, and research on the law of gob surrounding rock movement and destruction, laws ofsurface’s movement, deformation and damage characteristics above the mined-out area, gobfracture rock mass physical and mechanical characteristics.Analyse the mechanical properties of steep coal seam gob collapse, regard properties ofdifferent buildings as different new load. Put the steep coal seam gob geological condition asprototype, do the numerical simulation calculation by means of FLAC3D. Numericalsimulation is divided into four parts: first, mining subsidence process simulation, analyse lawsof overlying strata’s movement, deformation and damage under multi-layer miningsystematically. Second, simulate the stability of the proposed site under construction loads byapplying different load in different locations in the proposed site. Third, add the uniformlydistributed load on proposed site to simulate overlying strata activation deformation above thegob under this load and effect of the proposed site. Forth, evaluate the stability after20yearsof the proposed site. Provide theoretical basis and advice for the utilization of the surfaceabove mined-out area and building safety.