A model test investigation on prestressed anchor cable support for the Haidong fault tunnel

The support of fault tunnels is one of the key factors limiting tunnel construction. Prestressed anchor cables are proposed as a new type of support. However, there are few quantitative studies on tunnel excavation failure and support mechanisms. On the basis of the background of the tunnel in the Haidong fault fracture zone of the water diversion project in central Yunnan and using the excavation compensation method, a self-developed three-dimensional geomechanical model box is employed to conduct tunnel excavation tests. The displacement field, temperature field, stress field changes and mechanical mechanisms under the support of prestressed anchor cables are studied, and the support effect of high preload anchor cables is verified in practical engineering. The test results show that high pretightening force anchor cable support can better influence the self-bearing capacity of the surrounding rock. When overload failure occurs, bolts are subjected to brittle fracture failure, whereas anchor cables experience flexible bending deformation failure. The area enclosed by the characteristic curve of the surrounding rock after anchor cable support and that of the unsupported surrounding rock can be used as a potential quantitative representation method for the increase in the self-bearing capacity of the surrounding rock. Field monitoring results indicate that bolt support at nonfault locations and anchor cable support at fault locations have better effects on controlling surrounding rock deformation.