THE INFLUENCE OF GROUNDWATER LOWERING ON THE SHAFT WALL RUPTURE

In Huaibei the shafts are deformed and ruptured heavily in some mining areas,the main inducing factor of which is the additional stress formed by the water lowering in the lower aquifer.The numerical modeling calculation and analysis are conducted using the ［2D-σ］ software.It is considered that the shearing stress is produced by the relative displacement between stratum and shaft due to the groundwater lowering,its size is directly proportional to the water level drawdown and relative displacement;the change of axial stress is not apparently with depth but largely with the water lowering in the lower aquifer;the shaft wall rupture occurres firstly on its internal margin,then expanded progressively outward,and the rupture degree is increased along the depth direction;when the water lowering is occurred simultaneously in both No.1 and lower aquifers,the variation regularities of axial stress and shearing stress are similar to that during the water lowering in the single aquifer,but the variation amplitude of axial stress is increased obviously;and the raise of shearing stress is occurred in the upper aquifer.The abovementioned results of modeling calculation and analysis are conformable basically to the shaft wall deformation and rupture in Huaibei mining area.