Research On Roadway Floor Heave Mechanism And Control Technology Based On Stress Evolution Of Dynamic Pressure Roadway Floor

The mechanism of floor heave of dynamic pressure roadway has not been completely understanded.This paper,whose project background is Jingfu mine,firstly analyses floor stress,deformation and evolution law of destruction in different dynamic pressure stages of different coal pillar width with the numerical simulation.The mechanism of floor heave is revealed.At the same time determine the reasonable width of coal pillar according to the deformation of surrounding rock.Then,a theoretical analysis method is applied to establish the stress model of floor of different coal pillar widths,and the relationship between the width of the pillar,the two side vertical stress of the roadway,the thrust angle(the angle of non vertical force in the section coal pillar acting on the floor between the vertical force),the width of the bottom relief zone and the width of the sudden increase of floor heave and the stress and strain of the floor are analyzed.According to the research on the mechanism of floor heave,different schemes of control floor heave are designed,in which the stress,deformation and failure laws of roadway surrounding rock are studied by numerical simulation,and a reasonable supporting scheme is determined.Finally,verify the control effect of the new support scheme on the deformation of the surrounding rock according to the field test,,and summarize the factors of floor heave of Jingfu dynamic pressure roadway,the main achievements are as follows:(1)The stress law of surrounding rock lof roadway can not reflect the trend of roadway floor heave after mining stably,but the horizontal displacement of floor and floor heave of roadway varying with the width of coal pillar is almost identical,so that roadway floor horizontal displacement of the two sides is a microcosm of the floor heave.(2)There are different reasons for the floor heave in each period of dynamic pressure roadway.But the cause of the floor heave is that the two sides are subjected to vertical stress or thrust.They lead to heave through two aspects:(1)Vertical stress directly produces secondary stress on the floor.The horizontal force of thrust is applied to the floor of the roadway;(2)the vertical stress and thrust through influence the two sides of roadway to indirectly effect floor heave deformation.And the greater the deformation of the two side the more easy to heave.(3)The floor heave of roadway mainly occurs in the stable mining stage of adjacent working face.This is due to the instability of the key block B,resulting in a larger thrust in the section column,which can greatly improve the stress and deformation of roadway floor.The greater the thrust angle,the greater the stress of the roadway floor.And the thrust has a certain range.Therefore,the floor of coal pillar can be divided into the floor heave pressure relief area,the floor heave surge area and the floor heave reduction subdistrict.The sudden increase area of the floor heave is the location of the thrust.The influence of the width of the floor pressure relief area and the width of the sudden expansion area on the floor stress of the roadway is achieved by changing the width of the thrust or the distance from the roadway to the thrust.The larger the width or the smaller the distance is,the greater the degree of influence is.(4)Thrust block tunnel in the coal pillar have the function of reducing the floor heave.With the distance from thrust block tunnel to the 15202 roadway raising,floor heave of roadway increases linearly;The heave increases with depth of pressure reliefing groove decreases linearly,And the pressure relief slot has the function of transferring the stress of the roadway floor to the depth of the roadway surrounding rock.The deeper the trough,the transfer effect is better,but the pressure relief groove on the roadway deformation has little effect on sides and roof;inverted arch + floor bolt greatly reduces the deformation of surrounding rock,which is the best heave control scheme.(5)Floor heave of Jingfu 15202 roadway is mainly due to the presence of strong mining stress,thick mudstone in floor and poor support.The reasonable width of the coal pillar is 25 m.