Development of a Hollow Cylinder Torsional Apparatus for Rock

The mechanical characteristics of rock subjected to the changing of the principal stress magnitude and orientation caused by excavation are significant for the construction of larger and deeper underground engineering. However, there have been few experimental studies on rock mechanical characteristics under the changing principal stress orientation due to the lack of the test device. Hence, in this paper, a new rock mechanical experimental technique and device was developed to conduct the complex stress path with coupling variations of stress magnitude and orientation. The theoretical principle and apparatus composition were introduced in this work, and two test cases were conducted to verify its feasibility and reliability. This study has important practical significance and scientific value for promoting the technical level of rock mechanical test and enriching the theoretical frame of rock mechanics.