Development and application of physical simulation test system for small and medium-sized tunnels based on biaxial motor loading

To study the failure process of deformation and evolution mechanism of the surrounding rock in deep tunnels, as well as to solve the key problems of the current tunneling test system, a new motor biaxial loading system with compact structure, moderate size and stabilized loading is developed for simulating physical tunnels. The system consists mainly of a frame-type reaction frame, a servo-controlled motor testing system, a self-developed digital photographic deformation measurement system and auxiliary devices for excavation. It can be used for the physical simulation tests on small and medium-sized tunnels and the uniaxial and biaxial compression tests on standard or non-standard specimens made of the common similar materials. Finally, the uniaxial and biaxial compression tests on the rock-like specimens and the simulation experiments to study the deformation evolution of the surrounding rock in mixed strata are performed to verify the feasibility of the test system. Partial experimental results are basically consistent with those of the similar studies, which indicates that the poposed test system meets the needs of studying the stability of the surrounding rock and other issues. Furthermore, the results may also provide reference for the related researches. © 2020, Editorial Office of Chinese Journal of Geotechnical Engineering. All right reserved.