Development of an integrated hydro-mechanical coupling test system for meter-scale fractured rock masses in laboratory

To address the issues of bank slope deformation, landslides, and associated geological disasters caused by the impoundment of high dam reservoirs, the author, based on the proposed idea of constructing an external high-pressure hydraulic test chamber, has developed for the first time the CJ3000 rock mass hydraulic coupling test system (CJ3000 RTS). This system enables hydraulic coupling tests on meter-scale rock mass specimens to be conducted under controlled laboratory conditions. This paper systematically presents the design and development of the above system, which includes the equipment functions and the main technical specifications, seven major innovations, the performance testing results, the experimental operation and control procedures, etc. The total weight of this test system is 200 tons, and it is built on a soft soil foundation. The test system can provide a maximum vertical reaction load of 30,000 kN and a maximum horizontal reaction loads of 20,000 kN in two directions. The water pressure in the sealed cabin and the seepage pressure of the rock mass specimen are independently controlled, with a designed water pressure of 3 MPa. A new type of high-precision magnetostrictive displacement sensor resistant to high water pressure has been developed, and an experimental operation procedure for conducting multiple spatial target positions with large-scale equipment have been proposed. Finally, a mechanical test under triaxial hydro-mechanical coupling conditions was carried out on a basalt specimen with a size of 50 cm × 50 cm × 100 cm, and preliminary application results were obtained. The study demonstrates that the test method proposed is feasible, and that the developed CJ3000 rock mass hydraulic coupling test system is effective. This work is of significant importance for advancing research on the mechanical properties of rock mass under complex structural and stress conditions, particularly regarding their hydraulic coupling characteristics.