Abstract: Tilt test is a common method to obtain the basic friction angle of rock. However, the existing tilt test technology has not formed a recognized standard, leading to an obvious difference between the test results of the same kind of rock materials. To solve this problem, an inclinometer was developed to measure the basic friction angle of rock based on the existing tester structure and testing mechanism. A series of multi-scale specimens with dimensions ranging from 50 mm to 150 mm in length and 25 mm to 75 mm in height can be tested. The high-precision rotation control of angular speed ranging from 6(°)/min to 60(°)/min can be realized through the servo motor and the high-speed ratio reducer. The corresponding test parameters, such as specimen’s sliding distance and inclination angle, can be monitored and recorded in real time. Then, the operation flow of testing basic friction angle was put forward. The main factors that have obvious effects on the experimental results were analyzed, such as specimen size and processing technology, angular velocity, test results criterion and the dryness of the structural plane. In this paper, the basic friction angles of 11 specimens, including granite and diabase, with discontinuity size of 100 mm×100 mm were tested, and it provided a reference for the test specification of inclinometer.

Key words: inclinometer, basic friction angle, structure design, control, pull test