Study On The Instability Mechanism And Control Technology Of High Stress Red Shale Roadway In Ping'an Phosphate Mine

Phosphate rock is an important non renewable resource,which has been listed in China's strategic mineral catalogue and plays an important role in the national economy and human survival.Kaiyang Phosphate Mine,as a rare phosphorus rich deposit in China,mainly mines the phosphorite of Doushantuo Formation in the Upper Sinian system.The main development roadways of the mine are generally arranged in the red shale in the footwall of the phosphate rock.However,the red shale has the characteristics of fast weathering after exposure,water swelling and argillization.With the continuous development of mining to the deep,the brittleness of the red shale is weakened under the action of high stress,and the plasticity is improved It shows the characteristics of high stress soft rock.At the same time,the research shows that under the coupling effect of complex geological environment and high stress conditions,the red shale surrounding rock is prone to composite failure,such as shear expansion,large deformation rheology and water swelling.The roadway is characterized by a variety of failure forms,such as section shrinkage,spalling,caving and so on.The surrounding rock is seriously damaged,and it is difficult to effectively support.Therefore,in-depth study on the instability mechanism of high stress red shale roadway has important theoretical significance and practical guiding value for ensuring the safety production of phosphate rock.Based on the engineering background of 844 middle section transportation roadway of Pingan Phosphate Mine in Kaiyang,aiming at the problems existing in the control principle and technology of high stress red shale roadway,this paper comprehensively uses the research methods of physical experiment,numerical simulation,theoretical analysis and field application to analyze the deformation and failure characteristics of high stress red shale roadway,the change law of mechanical properties of red shale under dry wet cycle,and surrounding rock control technology The problem is studied.The main conclusions are as follows:(1)Based on the field investigation of 844 middle section transportation roadway in Ping'an phosphate mine,the comprehensive analysis of borehole peeper,multi-point displacement meter,anchor cable dynamometer,vibrating string earth pressure box,field and mine pressure monitoring is used to obtain the failure characteristics of high stress red shale surrounding rock.(2)The mechanical properties,pore size distribution,porosity and effective porosity of red shale before and after cycling were tested by mechanical test,mercury intrusion test,X-ray diffraction(XRD)and scanning electron microscope(SEM),and the mineral composition of red shale was tested.Combined with the microstructure characteristics of red shale voids,the water absorption and permeability of red shale under different dry wet cycling conditions were studied The micro change of softening effect.(3)Through the use of FLAC3 D digital simulation software,the stress distribution of roadway surrounding rock with different buried depth and spacing of piles,the increase of plastic zone expansion range and the displacement of roadway surrounding rock roof and wall are analyzed.The deformation and failure of high stress red shale under different conditions are analyzed,and the influence of different factors on the stability of red shale roadway is obtained The influence and failure characteristics of the structure.(4)According to the specific situation of 844 middle section transportation roadway,through the process control technology,support selection principle and strengthening support technology system,this paper puts forward the control technology idea of roadway and the support form of pile+ retaining wall + anchor mesh cable shotcreting;through the numerical simulation and field application of different support measures and original support measures of 844 middle section transportation roadway.