A newly-built geomechanical model test system and its application

In order to further improve the deficiencies of the model test in the field of underground engineering,a new set of experimental system of the geomechanical model was developed independently. To verify the feasibility and sta- bility of the new-built system,a large-scale similar model test was carried out based on the study of the deformation characteristics of surrounding rock during the excavation of a coal mine roadway. The performance was verified by com- paring the test results with the field test results. The innovations are as follows:① 280 hydraulic actuators are used to realize active and steady loading in various directions,which can restore the distributional characteristics of the in-situ stress field in the surrounding rock. ② Expanding the effective loading area significantly reduces the effect of size effect and boundary conditions on the accuracy of the test results. ③ For the first time,EDC servo hydraulic control system,photoelectric encoder and real-time data transmission system are adopted to realize real-time data acquisition and improve accuracy. The test results show that during the excavation and support of roadway,the deformation law of surrounding rock of model roadway basically agrees with the field measurement,and the main characteristics of sur- rounding rock deformation are basically the same. The system is verified to be able to better reflect the dynamic evolution characteristics of the surrounding rock of the prototype roadway and has certain engineering application value. It provides a good way to study the stability of surrounding rock in underground engineering.