Development and test analysis of borehole in-situ rock mass shear measurement system

The pre-drilled rock shear measurement system can measure the internal friction angle and cohesion of in-situ rock in mines. Compared with the traditional laboratory test and field tests, such method can keep the essential state of rock mass to the maximum extent, and obtain the test data conveniently and quickly. Firstly, the overall design idea of the system was elaborated, and the pre-drilled in-situ rock shear equipment was successfully developed and the data acquisition and storage software platform was built. Secondly, the test data processing method was developed, based on the working principle of the shearing instrument, and the specific test procedures were formulated by supporting a complete measurement system test device. Finally, in order to verify the engineering applicability of the system method, a calibration test was carried out on the measurement system, and a rock mass intrusion test and shear test were carried out on the concrete platform. Compared with the indoor direct shear test, the shear test results show that the internal friction angle is 24.77%-41.33% smaller, and the cohesive force is 13.11%-32.84% smaller. In view of the difference of the test results, the instrument equipment and test methods are analyzed. It is pointed out that the test errors mainly come from the change of equipment shear loading mode and the difference of rock mass direct shear test method. The research results provide new ideas and methods for the accurate measurement of mechanical parameters of mine rock masses, and also provide references for subsequent system improvement design.