Formation process and mechanism of seepage channels around grout curtain from microseismic monitoring: A case study of Zhangmatun iron mine, China

摘要

The grout curtain in Zhangmatun iron mine, China, suffers from the leakage of water due to the influence of multiple factors including inadequate grouting area, weak rock and mining disturbance. Water seepage through rock mass around the grout curtain further deteriorates the water plugging'effect of the grout curtain and poses a potential hazard to workers underground. Thus, a microseismic (MS) monitoring system was established in the Zhangmatun iron mine. In the present paper, a MS monitoring analysis method for assessing a potential seepage channel is proposed. Using the proposed MS monitoring analysis method, the dip, dip angle and center depth of the potential seepage plane across the grout curtain in Zhangmatun iron mine are determined to be 126.1 degrees E, 53.97 degrees and 275 m, respectively. The spatial and temporal behaviors of density distribution, source parameters and cracking type of the seismic source are analyzed to reveal the initiation, propagation, coalescence of seepage channel located at the southwest of the iron mine. Four types of local seepage channel formation, processes are summarized by correlating the mechanism of microcracking. Two main weak areas around the grout curtain at the levels of 230 m and 318 m are identified and two seepage paths whose water discharge points are localized to the roof of stope 9, 10 and sidewall of stope 10 are determined, respectively. Our study helps to get a better understanding of damage and failure of rock mass around grout curtain and thus provides a basis for taking reinforcement measures to secure the stability of grout curtain in mines.