Development and applications of physical model test system with true triaxial loading unit for deep tunnels or roadways

A large-scale physical model test system with true triaxial loading unit and digital photogrammetry is developed. Using this test system, it is possible to study the stability of rock mass and support control technology for the deep rock tunnel with an overburden of over 1000 m. The test system consists of a reaction frame, a hydraulic control unit with oil-driven actuators and vacuum oil feed-back pump, a deformation and stress measuring unit with self-developed digital photogrammetric technology and stress measuring method, and tunnel excavation and support instruments. Large-scale model with a size of 1000 mm×1000 mm×1000 mm can be used in this test system. Two model tests are presented. One is analyzing the deformation and stress distribution of a deeply buried tunnel. The other is reproducing a local fracture phenomenon. The test results show that the test system is useful for investigating the deformation and fracture laws of deeply buried tunnels such as mining roadways and TBM tunnels during excavation and supporting, and the mechanism of stability control for surrounding rock masses.