Experimental study on microseismic source location of three-dimensional section arc anisotropic wave velocity model

Abstract To enhance the capability of microseismic monitoring, locating, and early warning for mining dynamic disasters, and to strengthen the technological measures for geological disaster prevention in mining environments. Large-scale three-dimensional similar material model experiment was conducted indoor to measure the microseismic signals generated by artificial seismic sources. The equivalent path and equivalent wave velocity of seismic wave propagation under complex conditions in the mining area were defined. Based on the assumption of layered homogeneous media and Snell's law, a section arc anisotropic wave velocity model was developed to account for deformation in the goaf overburden, and the equivalent wave velocity was calculated. By comparing the measured values of equivalent wave velocity with the calculated results from the model, the variation characteristics of equivalent wave velocity within the goaf overburden were analyzed. Based on the source location principle of arrival time theory, the differences in location accuracy between two location velocity models (a section arc wave velocity model and an undetermined wave velocity model) were compared for artificial seismic sources geological model experiment. The research findings indicate that: (1) The equivalent wave velocity within the goaf overburden shows weak regularity, exhibiting significant anisotropic features in wave velocity. Due to the distribution of the layer separation and void, a “remote point reaching first” phenomenon occurs; (2) To address the “three zone” structure of the goaf overburden, a segmented wave velocity model is established. It assumes that the deformation of the goaf overburden is described by a section arc surface and uses Snell's law to determine the seismic wave propagation path across rock layers; (3) In model experiment, the section arc wave velocity model, through adaptive corrections and zonal combinations, effectively reflects the anisotropic characteristics of wave velocities in the goaf overburden, with the equivalent velocity deviation controlled within 10%; (4) Compared to location method using undetermined wave velocity model, the section arc wave velocity model method significantly reduces locating errors. The average location accuracy for the unexcavated and full excavation models improved by 71% and 83%, and it also restrains the volatility of location results.