Damage Evolution Characteristics Of Surrounding Rock In Deep Fault-bearing Structural Roadway Under Mining Disturbance

Geological conditions for mining in karst areas are complex,and mine dynamic disasters frequently occur.There are relatively few studies on the mining induced disaster mechanism of surrounding rock in mining roadway of gold deposit in karst area,which need to be further explored.This article takes the deep fault-bearing structural roadway in the Lannigou gold mine in southwestern Guizhou as the research object.In order to explore the damage characteristics of the surrounding rock of deep faultcontaining structural roadways under mining disturbance,research methods such as investigation,numerical simulation,theoretical analysis and monitoring are comprehensively adopted.The deformation and failure characteristics of roadway under mining disturbance,the evolution law of surrounding rock fracture and its fractal evolution process are studied,and the evolution law is verified based on microseismic monitoring method.The research results are as follows:(1)We can understand the roadway damage by the investigation of the underground roadway damage.With the original support condition of roadway,the deformation and failure characteristics are mainly as follows: cracking and caving of roadway roof、the rock mass of the two sides is broken and loose and the different degrees of convergence in the section.The failure modes of the failure deformation are mainly tensile failure and shear slip failure.(2)The stress-strain plastic distribution and roadway failure of the roadway and surrounding rock before and after mining disturbance are analyzed by 3DEC numerical software.It is found that the spandrel part on the right side of the roadway passes through the interface of the rock formation,which is simple to cause damage.The part that crosses the interface should be reinforced.When the roadway is driven into the fault,due to the low strength of the internal filler,weak bond and extremely loose,it is necessary to pay attention to the stability of the roadway support structure at all times,and the bolt can be replaced appropriately to increase the support strength.(3)According to the results of numerical simulation,two dangerous sections which are easy to damage are found,and a section is added in the middle of the rock stratum where the roadway is located as the control group.In this paper,UDEC software is used to simulate the three sections from excavation to failure,and the fracture evolution law in the process is studied,and the fractal dimension is introduced to evaluate the damage degree of roadway.If the lithology is good and the damage degree is more than 11%,the roadway section and surrounding rock will be damaged.if the rock mass lithology is poor,the roadway section and surrounding rock body will be damaged when the damage degree reaches about 8%.On the other hand,if the box dimension of the fracture reaches about 1.4,the roadway section is likely to be damaged.(4)Based on the analysis of the corresponding relationship between the time and space distribution characteristics of microseismic events and the excavation construction process of the eastern section of 30# middle roadway,it is found that the peak period of microseismic activities corresponds to the construction activities.The time-space distribution map of microseismic events is consistent with the distribution area of roadway fracture in the numerical simulation results.Because of it,the damage and stability of roadway surrounding rock can be evaluated according to the intensity of microseismic events and other microseismic activity indexes,so as to guide the production.