Installation Methods Evaluation for Tunnel Microseismic Monitoring Sensors

In response to the need for tunnel microseismic (MS) monitoring and to avoid problems such as the damage of the primary support caused by drilling and installing acceleration sensors, this article proposes a new sensor installation method and manufactures a novel right-angle bracket for vibration acceleration sensor installation. This study examines the measurement errors caused by vibration transmission through the right-angle bracket. Modal analysis revealed that the low-order mode of the right-angle bracket system is about three times or more the main frequency of tunnel microseism, making it suitable for tunnel microseismic monitoring. Combining field experimental tests and numerical simulation, the time and frequency domain responses of the installation bracket under impact load were studied. The vibration differences captured by the sensors installed in different locations were compared and the reasons for the vibration monitoring differences were analyzed.