A Large-Scale Model Test System for Stability Study of Tunnel Under Static-Dynamic Load

In order to study the stability of tunnels under static-dynamic load, a new large-scale static-dynamic model test system was developed. The system was composed of a static loading unit, a dynamic loading unit, a data acquisition unit and a test bench, which were specially designed to overcome the technical problems of large-scale static-dynamic model test, such as dynamic loading and control, high-rate strain measurement and easy operation. The system used a model of 3600 × 3600 × 2500 mm in size to study a larger load disturbance area than static tests. It can accurately apply three-dimensional gradient static stress and dynamic load with adjustable amplitude (or magnitude), frequency and waveform to simulate the true geo-stress field and disturbance field, and accurately and rapidly collect displacement, stress, strain, velocity, acceleration and other important parameters of the model. In addition, it was convenient to adjust the scale of the model, remove and retain the test model. The system was used to carry out a static load model test and a static-dynamic load model test with a tunnel as a prototype. The results of the tests were consistent with the numerical results by FLAC-3D, which proved the reliability and accuracy of the system.