Research And Engineering Application Of Fracture Mechanism And Spatial Expression Of Engineering Rock Mass

The study of focal mechanism solution is a hot and important issue in microseismic monitoring technology,which is of great significance for understanding the mechanical mechanism of rock failure and guiding engineering practice.In this paper,the expressions of three moment tensor inversion methods are derived firstly,and the source moment tensor is obtained by using the hybrid moment tensor inversion method with the highest accuracy.Based on the moment tensor theory,the rupture mechanism of the source event is explored.According to the time and spatial distribution of microseismic location,the spatial information expression of the main failure surface is analyzed,and its evolution trend is explored.The research results are as follows:(1)Based on the moment tensor theory,the Ohtsu decomposition method and the criterion of rock mass fracture type are only suitable for tension.The moment tensor decomposition model of rock mass under compression is introduced.By discussing the positive and negative of CLVD component,the calculation expression of CLVD component is expanded,and the ISO component is added to modify the criterion of rock mass fracture type;combining the revised criterion with clvd-iso diamond source type diagram,the characteristics of components of various rock mass fracture types are more vividly illustrated;aiming at the defect of MDC component in solving the occurrence of fracture surface,the tension source model is used to solve the occurrence of fracture surface;finally,taking Xianglushan tungsten mine as an example,the rationality of the improved criterion is illustrated by the motion angle of the source.(2)Principal component analysis(PCA)is used to quickly obtain the occurrence and evolution trend of regional principal failure surface.The method is divided into two parts:spatial principal component analysis(SPCA)and spatial temporal principal component analysis(TPCA).According to the location of microseismic events,the former obtains an ellipsoid through PCA to describe the shape and aggregation direction of the event cluster,and obtains the spatial information expression of the main failure surface according to the geometric characteristics of the ellipsoid;In the latter,a time window covered with a fixed number of events is slid on the event group to obtain the ellipsoid represented by each window,and the ellipsoids with different directions are separated to obtain the occurrence of the main failure surface at different times,so as to obtain the spatiotemporal evolution trend of the main failure surface.(3)Based on the research background of a large mountain sliding failure caused by blasting in Shizhuyuan Polymetallic Mine,the source mechanism analysis is carried out according to the received micro earthquake data,and the source moment tensor is calculated by using the hybrid moment tensor inversion method.According to the modified rock fracture type criterion,the probability of sliding failure is shear failure and shear failure;Produced by SPCA determines the mountain slip occurrence of failure face,tendency for NW319.26°,dip Angle is 81.62°,using TPCA analyses the damage the occurrence and evolution process,the occurrence of failure face similar to SPCA calculation results,the tendency to change direction by NW316.14°to NW317.47° direction,dip Angle of 87.96° to 85.05°,can be concluded that the damage is tendency of the development of the north,and dip angle decreases.The above methods can quantitatively and qualitatively analyze the process of rock mass fracture disaster,and provide an effective research method for advanced prediction of rock mass engineering disaster.