Research On Stress Distribution And Safety Control Range Of Overlying Rock Of Mining Roadway Under The Influence Of Fault

The existence of faults changes the stress field of the rock mass.During the mining process of the working face,the deformation and failure law of the surrounding rock of the roadway and the distribution law of the rock pressure of the working face are changed,which adversely affects the stability of the surrounding rock support system.Therefore,based on theoretical analysis,similar simulation,numerical simulation and research methods,this paper studies the migration and stress evolution of the overlying rock under the influence of faults,and its influence on the deformation of the roadway.Based on this,a full section with grouting as the core is proposed.The main research results of anchor-grouting coordinated support technology are as follows:(1)Using the theory of elasticity,the fault is regarded as a plane problem,and the stress state near the fault is studied.It is deduced that when the fault is at an angle of ?l to the in-situ stress,the fracture is most likely to undergo tensile failure first near the end of the fault,and the main stress trajectory of the nearby area when the fault is sheared is known;Based on the influence of the fault,a mechanical model of the surrounding rock of the near-fault roadway is established.By introducing the HoekBrown strength criterion as the basis for judging the instability of the surrounding rock,the instability range of the surrounding rock of the roadway is 2.32 m.(2)Based on the actual engineering and geological conditions of 2401 working face in 24 mining area of Shunhe Coal Mine,the physical similarity simulation method is used to simulate the whole process of working face from normal mining to close to the fault,and obtain rock collapse shape,crack development characteristics,fault activation process and stress evolution law Under ordinary mining conditions,every25?30cm mined will cause the roof to break and collapse.The compression period is about 30 m based on the calculation of similar ratio,which is basically in line with the site engineering;the supporting stress starts to rise when the working face is about 50 m away from the fault.This section of the roadway is strongly affected by the fault activity,so it is necessary to strengthen the support at the roadway stage within 50 m from the fault to prevent the roadway from instability,deformation and even impact damage.(3)Using numerical simulation software,the stress characteristics and rock migration law under fault mining conditions and ordinary mining conditions are studied.The results show that as the working face approaches the fault,the fault will be gradually activated,and the movement of the overlying strata will cause the load to shift to the position of the roadway on both sides of the fault.At this time,the stress concentration on both sides of the fault is intensified,and the plastic failure range is expanded,which is not conducive to maintaining good stability of the roadway.After strong over the fault,as the working face continues to break through the fault,the working face stope stress gradually returns to normal,the degree of plastic damage decreases,and the roadway stability gradually improves.(4)Based on analysis of the theoretical model,numerical simulation and engineering geological conditions,the roadway support plan is optimized.A full-section anchor-net-cable combined support technology with long anchor cables as the core is proposed,and the rationality of the support scheme is verified by on-site monitoring of the two sides of the roadway and the displacement of the roof and floor.There are 57 figures,7 tables and 106 references in this paper.