Stability of shallowly buried soft rock tunnel anchorage by in-situ model tests

To study the stability (strength characteristics, deformation laws and long-term stability) of the shallowly buried soft rock (mudstone) tunnel anchorage under heavy load, based on a Changjiang bridge tunnel anchorage project under construction, the 1:10 reduced-scale models are used for field tests on the shallowly buried soft rock (mudstone) tunnel anchorage. According to the research, the shallowly buried soft rock (mudstone) tunnel anchorage still has the bearing capacity. Under the condition of design load or even several times the design load, the tunnel anchorage also has the long-term stability. The failure mode of the shallowly buried soft rock (mudstone) tunnel anchorage is as follows: the surrounding rock at the upper of the anchorage body breaks into blocks first, then the bottom of the anchorage body slides along the contact surface with the surrounding rock. The bottom boundary of the destroyed area is the contact zone of the anchorage body and the surrounding rock. The anchorage body has no damage. Besides, the spatial distribution laws of the creep deformation of surface surrounding rock and the deformation laws of the surface and deep surrounding rocks are also investigated. The research results may provide reference for the similar projects.