Prevention And Control For Stress Induced By Wedge Of Steeply Inclined Deposit

Among the metal underground mining mines,steeply inclined bedded orebody accounted for about 20%.And with more and more open-pit translating to underground mining,the proportion of the steeply inclined bedded orebody in underground mining will be further increased.After this kind of orebody is mined to a certain depth by caving method,the ground pressure appears obviously.And with mining depth deepening,the appearance of ground pressure becomes severely,the weaker part of surrounding rock will continuously deform and be destroyed under high stress.It is difficult to repair the destruction area,and it has a great threat to the normal production.Taking the central area of Gongchangling underground iron mine as the engineering background,this paper studies the causes of ground pressure appearance in this kind of mine and the prevention and control method,so as to ensure the safety production.The paper mainly carries on researched on the following six aspects:(1)The areas of the ground pressure appearance of development engineering and stope preparation work have been investigated on-site.The deformation and failure mechanism of roadways and the sources of stress are analyzed.Compared the ground pressure appearance occurred in the Gongchangling underground mine with the traditional form of ground pressure appearance,the basic features of ground pressure manifestation is revealed.It is concluded that the hanging-wall wedge rock mass formed after mining resulted in the ground pressure damage.(2)The mechanical model of wedge rock mass is established.The elastic mechanics theory is used to calculate the analytical solutions of the model under different conditions.The stress of each point at the top of the wedge model is worked out.Combined with the field failure of the roadways and the location of surface cracks in subsidence area,the wedge rock mass of hanging wall was detected.The stress distribution in the wedge rock mass is analyzed(3)The discontinuous deformation analysis(DDA)is applied to simulate the wedged ground pressure on the hanging wall.Based on the changes of stress and displacement of monitoring points in the hanging-wall rock mass after excavation,the change rule of the ground pressure caused by the wedge rock mass with mining depth and the action range in the surrounding rock of the hanging-wall are respectively established.(4)The displacement change of roadways is monitored by convergence monitoring method.The law and influence factor of the ground pressure activity of mining preparation engineering under mining are analyzed to establish the sphere of influence of the ground pressure caused by wedge rock mass and the failure mechanism of roadway caused by mining pressure.(5)For the problem of the ground pressure appearance caused by the hanging-wall wedge rock mass,based on the mechanical analysis and numerical simulation result of wedged ground pressure,a comprehensive prevention and control plan including development under pressure depression,mining under unload pressure and roadway reasonable sectional dimension reduction of roadways is put forward.And the above plan have been carried out on the sense,and get good effects.(6)For the feature of ground pressure appearance in stope preparation work,based on the monitoring result of the ground pressure in mining preparation engineering,it is researched that the mining method with the help of wedged ground pressure,and it is put forward that the single-way induced caving mining method and double sublevel synchronous induced caving mining method.This paper suggests the spray anchor net supporting form to strengthen the wall support.And the field test proves that the ground pressure control effect is good.