Abstract: To study the failure mechanism and failure mode of tunnel-type anchorage at soft rocks, overloading failure test was conducted through 1∶10 scale field model of tunnel-type anchorage. The surface deformation and internal deformation, the results of borehole inclinometers and the cracks of tunnel-type anchorage model in the overloading process were analyzed. The deformation-load curve and the characteristics of deformation failure of tunnel-type anchorage model under thrust were obtained. Furthermore, the results were comprehensively analyzed in association with numerical simulation results. Research results showed that: similar with the deformation failure of soft rock under loading test, the whole process of the deformation failure of tunnel-type anchorage model experienced three stages. Destructive bottom boundary was formed by tension-shear between the bottom of anchorage and contact area of rocks. Due to upward extrusion, longitudinal tensile cracks of rocks above the anchorage and shear fractures with angle of about 45 degrees to the anchorage were formed. The ultimate bearing capacity of tunnel-type anchorage is mainly decided by the tensile capacity and shear capacity of rocks on the bottom boundary and top of the anchorage.

Key words: tunnel-type anchorage, scaled model test, numerica1 simulation, deformation and failure mechanism, failure mode