Time-lapse monitoring of hard-rocks properties in the vicinity of underground excavation

Studying the behavior of the rock mass is essential for developing a geophysical monitoring system, which allows continuous time-lapse monitoring of the state of the rocks environment. For example, rock mass monitoring might be a crucial part of a system for storing dangerous, especially nuclear waste in a geological environment. The goal of this project is developing a working system for long-term time-lapse monitoring of a geological environment using non-destructive geophysical techniques. The monitoring system works with geoelectrical and seismic properties of the hard-rocks environment. The system carries out 4D monitoring of the rock properties behavior in the close vicinity of an underground excavation. For the initial experimental measurements, two geophysical methods were chosen - electrical resistive tomography (ERT) and ultrasonic microseismic. The ERT method uses a set of 48 stainless electrodes 20 cm apart (9.4 m length of the profile in total) and the frequency of the measurements is six hours (i.e., four measurements per day). Currently the seismic uses frequency of five minutes between gathering one seismic record. Attention is paid to the behavior of a significant fracture located in the middle of the measuring system. The monitoring device collects data that are being sent via the LAN connection to the project members' computers.