Study of a Seepage Channel Formation Using the Combination of Microseismic Monitoring Technique and Numerical Method in Zhangmatun Iron Mine

Abstract

In 1996, a grout curtain was constructed in the Zhangmatun Iron Mine near Jinan City, China, which is subject to large groundwater inflows, to decrease the water volume rushing into the mine workings. However, water inflow has recently been increasing in the southwestern area through a seepage channel, which has resulted from the failure of the grout curtain. To understand how the seepage channel formed, the microseismic (MS) activities located in this area were studied and a numerical model was supplementarily used to analyze the damage zone. It is found that the seepage channel formation process is significantly affected by the distance between mining activities and the grout curtain. Mining activities periodically approached and retreated from the southwest grout curtain, causing periodically active and inactive microseismicity, and eventually the grout curtain failure. The damage zone in the grout curtain obtained from the numerical analysis coincides with the seepage channel, especially in the area where the distance between the grout curtain and excavation is less than 35 m. Therefore, the combination of MS monitoring and numerical analysis of damage zones can provide us with an overall understanding of the formation process and causes of the seepage channel.