| Taking the actual geological conditions of Sangbei Coal Mine as the engineering background,in view of the deformation and failure characteristics of the surrounding rock of the cavern and the failure of the U-shaped shed supporting structure,the research content is divided into three parts through field investigation,theoretical calculation,laboratory test,numerical simulation and other means.A two-part hierarchical progressive study.Firstly,the influencing factors of the surrounding rock stability of the space crossing roadway are studied,and then the stress response and surrounding rock stability of the lower chamber during the complete mining process are analyzed.According to theoretical calculation and numerical simulation analysis,the surrounding rock instability characteristics of the chamber are analyzed.,put forward the principles of full-section grouting,deep and shallow hole grouting and large anchoring circle support,designed a control scheme for the surrounding rock of full-section anchoring support that can be reinforced as a whole,and carried out on-site practice,and obtained the following main results:（1）The mechanical model of surrounding rock stress distribution between roadways was established,Based on the theoretical analysis of the conditions for determining the instability of the surrounding rock,the influence mechanism of the roadway layout on the stability of the surrounding rock of the crossing roadway is obtained,which provides the basis for the initial scheme design for the subsequent numerical simulation.（2）The spatial intersection roadway model was established by the FLAC3Dsimulation software,and the influence of the driving process of the two grade separation roadways,different angles,different vertical distances and other factors on the stability of the surrounding rock between the roadways was analyzed,and the stress response characteristics of the excavation disturbance were clarified.Early control provides guidance.（3）According to the transmission mechanics model of the supporting stress floor,the distribution characteristics of the supporting stress increment in the space crossing roadway are obtained.Through the numerical simulation study,it is found that the supporting stress is affected by the vertical stress,horizontal stress and shear stress concentration of the floor respectively.About 17 m,15 m,10 m in front of the front,the maximum stress concentration factors are 2.4,1.4 and 0.76 multiples the vertical stress,respectively the stress concentration influence depths are 18 m,13 m,30 m below the bottom plate,respectively.（4）The stress response process of the surrounding rock of the lower chamber during the mining period is divided into four stages:stress unchanged,stress growth,stress release,and stress recovery,corresponding to the horizontal distance between the working face and the central axis of the chamber more 30 m,30 m to 0 m,0m to-20 m,less-20 m distance.During the stress response process of the surrounding rock of the chamber,the vertical stress of the lower chamber side of the crossing is"blocked"by the upper roadway and transmitted downward.When affected by the mining stress,the surrounding rock stress of the upper side of the lower chamber is increased more significantly.（5）During the mining period,the deformation of the surrounding rock of the chamber is distributed asymmetrically.The movement of the roof is the smallest at the intersection,and the movement of the floor is the largest at the intersection.As the mining face approaches,the displacement of the surrounding rock in the chamber in the horizontal direction The growth rate increases,and the movement of the surrounding rock of the chamber within the horizontal distance of 20 m is strongly affected by mining,and the movement of the chamber floor and the right side away from the working face is more significantly affected by mining.（6）Because the surrounding rock of the chamber is relatively broken,the initial support capacity of the U-shaped shed is good,until the structural deformation of the U-shaped shed is seriously invalid due to mining,and the position where the deformation and instability of the chamber is the most serious is about 15m away from the intersection.The three support schemes are compared and demonstrated,and the full-section anchor cable+deep and shallow hole grouting support is determined.The mine pressure observation shows that the deformation of the surrounding rock of the cavern in this scheme is small,and the support scheme is proved in the effective support state feasibility. |
