Field model tests and bearing capacity analysis of tunnel anchorage of Jindong Bridge

Tunnel anchorage of Jindong Bridge is built in the complicated rock stratum, but there is no similar engineering experience for reference. In order to analyze the bearing capacity of tunnel anchorage of Jindong Bridge, a model test tunnel is excavated on the side slope of the mountain at the upstream side of the real anchorage to make a tunnel anchorage model of 1∶11; then, the backstepping method is adopted to conduct the model tests, including elastic-plastic stage tests, creep tests and full-load overload tests, as well as the supporting tests such as physical mechanical property tests on rock mass (rock block) and acoustic wave tests on rock mass. The test results show that the character of the model anchorage rock mass is basically the same as that of the real anchorage, the acoustic wave of the surrounding rock of the model anchorage is lower than that of the real anchorage, and the stratum of the model anchorage has a better geological representation. The model anchorage exhibits the approximate elastic deformation under the action of 8 times the design load, and there is no creep under the long-term action of 6 times the design load. It is deduced that the surrounding rock of the real tunnel anchorage has the overload stability coefficient of more than 8 and the long-term safety stability coefficient of more than 6. The results can be used as the reference for the engineering design of similar complicated surrounding rock.