Study On Microseismic Source Imaging Method Under Complex Medium Conditions

Recently,the underground deep mining activities in China have been increasing,resulting in frequent dynamic disasters.How to ensure the safety of underground engineering construction and operation has become one of the focuses of many scholars.The safety and stability monitoring and early warning of underground engineering is an important means and methods to ensure its safety.The essence of rock mass dynamic disaster monitoring is to monitor the damage and damage of coal and rock mass and the disaster process.Microseismic monitoring technology has become an important method for coal mine dynamic disaster monitoring by real-time monitoring of coal and rock mass stress field change time,position,energy and other multidimensional information to invert the dynamic evolution process of coal and rock mass structure instability.This paper takes the construction of microseismic source imaging method in complex media as the research goal,and constructs the source imaging method theory in complex media based on the basic theory of elastic wave and dynamics theory.The multidimensional imaging method of complex medium microseismic source is verified by theoretical calculation,laboratory test,numerical simulation and field verification.There are mainly the following aspects:1 Starting from the basic theory of elastic wave,the wave equation is derived,and then the commonly used Snel ' s law in optimizing the propagation path is introduced,and the shortcomings of the improved source location method based on this law are analyzed.Then,a multi-step location method for solving the microseismic source is improved.The method first seeks the optimal global velocity value,and then uses the improved analytical algorithm to calculate the source.The method has good adaptability to complex media.2 The improved microseismic source location method in this paper is compiled into the microseismic activity feature analysis software(ASP).The software can carry out real-time microseismic monitoring or analyze the historically stored microseismic data.The microseismic monitoring work on the engineering site needs to be carried out by using the KJ1501 microseismic monitoring system.3 Acoustic emission source localization experiments were carried out in the laboratory,and the ' refraction localization method ',' tomography localization method ' and ' multi-step localization method ' were used for localization calculation.The source localization results were compared to verify the feasibility of the improved ' multi-step localization method ' and higher positioning accuracy.4 By processing the microseismic monitoring data of a coal mine in Inner Mongolia from March 2018 to July 2019,it is verified that the microseismic monitoring system developed by the improved microseismic source location method in this paper can be used for microseismic activity monitoring.Through numerical simulation method,the mining process of the same mining face is simulated,and the stress distribution and microseismic activity process of several key nodes in the mining process are analyzed,and compared with the microseismic event calculated by the microseismic activity characteristic analysis software(ASP).It is proved that the microseismic monitoring system compiled by multi-step positioning method has higher positioning accuracy for geological disasters such as rock burst and water inrush that may occur during mining.It is of great significance to study the formation mechanism of coal mine dynamic disasters,prevent and control coal mine dynamic disasters,and ensure safe and efficient production of coal mines in China.