Research On Mechanical Properties And Disaster Mechanism Of Surrounding Rock In High Stress Red Shale Tunne

Kaiyang phosphate deposit in Guizhou is a rare phosphate-rich deposit in China,and the total proven resources are more than 1 billion tons.The roadways for transporting phosphate rock in mines are mostly arranged in red shale strata.The clay mineral content in red shale is high.Under the action of water erosion and weathering,swelling and disintegration will occur,showing obvious soft rock characteristics.Under the action of high stress,the red shale roadway in mine is mainly prone to spray layer cracking and spalling,bolt failure,local spalling roof caving and serious floor heave caused by water swelling of surrounding rock.The deformation and instability of roadway seriously affect the safety of mine production.In this paper,through the field investigation of the instability and failure of the high-stress red shale roadway,the mechanical properties and disaster-inducing mechanism of the surrounding rock of the high-stress red shale roadway are studied by theoretical analysis,laboratory test,numerical simulation and industrial test,and the following research results are obtained :(1)By collecting and summarizing the research results of surrounding rock mechanical properties and disaster problems of high stress red shale roadway,the instability mechanism of high stress red shale roadway,the mechanical properties of red shale and the research status of roadway control theory and technology are understood.(2)Through the uniaxial graded loading rock mechanics test,the mechanical properties and creep deformation law of red shale with different bedding angles after different dry-wet cycles are analyzed,and the disaster-inducing mechanism of surrounding rock deformation and failure of high-stress red shale roadway is found from the perspective of red shale bedding and mechanical properties.(3)According to the physical model test of the surrounding rock deformation characteristics of the red shale roadway,the evolution characteristics of the displacement field and temperature field of the surrounding rock of the roadway in the process of phosphate rock mining are studied by using the digital speckle measurement system and infrared thermal imager.It is concluded that the displacement of the roof and the right side of the roadway is greater than that of the left side and the floor.With the mining progress,the expansion range of rock displacement continues to expand to the surrounding rock of roadway;the temperature in the overlying strata area of the roadway roof and the right side is higher than that in the floor and the overlying strata area of the left side.The lowest temperature in the roadway is due to the excavation of the roadway in the pressure relief area.(4)Numerical simulation software is used to analyze the distribution of displacement field,stress field and plastic zone of roadway surrounding rock after the rock mass in inclined and horizontal strata exits the load.(5)By analyzing the deformation and failure characteristics of typical high-stress red shale roadway and the causes of roadway instability,according to the specific situation of roadway surrounding rock from 844 intersection to chute section,and with the help of roadway control theory,through the key technologies of shallow hole grouting repair,grid arch support and deep anchoring of small aperture anchor cable,the support method of shallow hole grouting + grid arch support + small aperture anchor cable is proposed and applied in the field.