Microseismic event monitoring of highly stressed rock mass around underground oil storage caverns

摘要

Acoustic emission (AE) and microseismic (MS) events are well-known indicators of fracturing or damage in rock subjected to high stress. Source location of the microseismic events enables assessment of the intensity and extent of excavation-induced rock mass degradation. Thus, microseismic event monitoring has been shown as a valuable means of stability evaluation of underground rock structures. In this study, microseismic event monitoring system is applied to highly stressed rock mass around U-1 underground oil storage caverns in Yeosu, Korea. The over-stressed rock mass zone is characterized by localized brittle failure accompanied by popping and spalling. In response to such problems, modifications were made to excavation designs and additional supports were installed. However, due to limitations of the existing monitoring method, a method of monitoring the overall behavior of the rock mass across the over-stressed zones became necessary in order to ensure the structural stability of the caverns and the safety of the workers during excavation processes.