Study On Stress Transmission Laws Of Mining Floor And Its Influence On Stability Of Floor Roadway

With an increase in coal mining strength, supporting and maintaining the cross-mining roadway with dynamic pressure have become increasingly prominent, expecially the roadway affected by dynamic preeure many times. Its mechanism is so complex to support, therefore, to research mechanism and control of floor roadway with dynamic pressure not noly has important theoretical significance, but also has important application value. Therefore, based on elasticity, this paper firstly analyzes the spread laws of floor abutment pressure in mining by using additional stress algorithm and combines the mining abutment pressure with stress of surrounding rock. And the elastic-plastic model of cross-mining roadway with dynamic pressure is established. In addition, under the conditions of mining coal groups, the features of deformation fracture and mechanism of grading support are systematically analyzed by numerical simulation and analog simulation. And the results were successfully applied to engineering practice of supporting cross-mining roadway with dynamic pressure. The main innovative achievements are as follows:(1) Based on the theory of semi-infinite in elasticity, the mechanical models of floor stress distribution and floor abutment pressure transmission are established by using additional stress algorithm. The distributing and transmission laws of floor abutment pressure during the mining process are analyzed and the changing laws of stress at a fixed point under the floor induced by abutment pressure are obtained.(2) The coupling of floor abutment pressure and roadway rock stress is achieved. Base on this and tri-linear rock stress-strain softening property, this paper establishes an elastic-plastic mechanical model of cross-mining roadway with dynamic pressure and analyses the distribution and deformation laws of surrounding rock during mining different coal. The relationship between the support resistance and deformation of cross-mining roadway with dynamic pressure is discussed and the expressions of stress and deformation of surrounding rock during mining the coal face are obtained.(3) With the help of numerical simulation method and similar material simulation method, this paper analyses the stability characteristics of cross-mining roadway with dynamic pressure under the condition of mining coal groups. And the laws of surrounding rock stress, size of plastic zone and deformation with the different coal mining orders, vertical distances from roadway to overlying workface and horizontal distances are got. The results show that: the order of top-down coal mining is more conducive to control floor surrounding rock. When the horizontal distance between roadway and overlying workface is near, the stability of surrounding rock will be impacted by the overlying mining face and the smaller vertical distance, the greater the impact. The arch lumbar side of the roadway near the workface is the most easily get into the damaged state and its extent of damage is the largest. It is the weak point for the roadway surrounding rock.(4) Using numerical simulation and similar simulation, this paper studies the control effects of different supporting strengthens of abutment pressure in cross-mining roadway with dynamic pressure. And this reveals roadway surrounding rock deformation characteristics of cross-mining roadway with dynamic pressure. Therefore, the idea of "stages" supporting is proposed. That is, the choice of different support programs is based on the different coal mining orders.(5) For the existing support problems of cross-mining roadway with dynamic pressure in Cross Haizi Coal Electricity Huaibei Coal Mining Co., Ltd., a stage supporting program with the core of grouting bolt is put forward. Through field observations, the results show that the support scheme can effectively control the severe deformation of surrounding rock and maintain the stability of roadway. And the roadway safety is greatly enhanced.