Laboratory model test on "wedge-effect" of pullout capacity of tunnel-type anchorage

The tunnel-type anchorage is the key force component to bear the main cable load of suspension bridge, and the mechanism of tunnel anchorage and surrounding rock joint bearing is very complicated. The simplified calculation model of tunnel anchor is established; and a formula for calculating the pullout capacity of tunnel anchor is deduced by using the wedge effect method. Furthermore, in order to verify the rationality and correctness of the "wedge effect" calculation method, the 14 groups corresponding indoor model tests are designed and carried out. Through the model tests, the uplift bearing capacity is obtained; and the relationship between the influence factors and the uplift capacity is studied. With the accurate related parameters of indoor model, using the calculation method of bearing capacity of indoor tunnel anchor model, and contrasted it with the results of model test, the results show that the theoretical calculation results are consistent with the law of influence factor and destruction characteristic. Research results show that it is scientific and reasonable to calculate the bearing capacity of tunnel anchorage by the simplified formula considering the "wedge effect". This calculation method has the characteristics of clear mechanical meaning and concise formula form, so as to provide reference for engineering practice.