Optimizing a Rock-Like Material Mix Design for Enhancing the Mining Fracture Monitoring Accuracy of Borehole Resistivity Method

Water disaster prevention and gas extraction in coal mining need to accurately determine the development strata of mining fractures. The borehole resistivity method (BRM) is an advanced technology to monitor the dynamic development of mining fractures during the construction of underground engineering. However, the huge difference between the physical property of the sealing material for the BRM and the surrounding rock affects the accuracy of monitoring data. With the gradual expansion of the application range of BRM, the requirements for the monitoring accuracy of the technology are getting higher and higher. Therefore, it is an urgent engineering problem to develop a new rock-like material (RLM) to further improve the monitoring accuracy of BRM. This study aims to optimize the RLM mix design for BRM by introducing a few conductive ingredients such as steel slag (SS), graphite powder (GP), and multi-walled carbon nanotubes (MWCNs). To be consistent with the field conditions, the curing temperature, curing age, and triaxial stress loading and unloading scheme of RLM were designed to align with the temperature change, monitoring period for BRM, and stress conditions in the coal mines. The porosity, resistivity, and triaxial compressive strength of all rock-like material samples were tested. The results show that optimal mixture of the RLM is 41.9