Methods of in situ strength testing of rocks and joints

The article offers in situ test methods for cohesion and internal friction angle in rocks and at joints. Technologies and instrumentation for shearing of rock wedges in an open pit mine and for laser scanning and digital imaging of local falls and breaks of inaccessible rock blocks in pitwalls have been developed and approved for constructing a limit equilibrium equation and for calculation of strength properties of rocks and joints. Rock wedges for the tests are prepared using various design drill rigs, the rock wedges are sheared using a 40-t jack placed in a special metal housing with an electric hydraulic pump. Exploration of inaccessible local falls in pitwalls uses electronic tachometers and 3D mine scanner. The tests and approval of the described exploration techniques have been carried out in open pits in Kazakhstan and Kirgizia.