Rock mechanics comperhensive study of tunnel anchorage for super large suspension bridge

Abstract

Aiming at bearing capacity problem of tunnel anchorages at Yaan side for Luding super large suspension bridge over the Dadu river, to study systematically the deformation, creep characteristics and bearing capacity of the tunnel anchorage and its surrounding rockmass by a comprehensive research method based on rock mechanic tests are proposed. The approach included in the research consists of in-situ geological investigation and rock mechanical tests, the 1:10 anchorage physical model test with the same rockmass at site of the actual schemed tunnel anchorage, and the numerical simulations related to bearing capacity evaluations of the actual tunnel anchorage. Several conclusions have been drawn. Geological representation of model tunnel anchorage is verified by comparing the surrounding rock geological condition and mechanical characteristics of model tunnel anchorage and actual tunnel anchorage is basically similar. Recommended test values of mechanical parameters of rockmass are proposed based on rock mechanical tests. In-situ scale model test results show that: (1) the maximum deformation of anchoring concrete-plug is 0.42, 2.50, 6.41 mm respectively under 1 P (design load), 3.5 P and 7 P, while the maximum deformation of surrounding rock is 0.25, 1.86, 6.59 mm respectively under 1 P , 3.5 P and 7 P. (2) Anchoring concrete-plug, surrounding rock and their dislocation experience deceleration creep and then tend to be stable, which belongs to attenuation type creep. (3) A characteristic point of anchoring concrete-plug model system is 5.25 P, which comforts code requirement. In addition, the technological line and achievement is an example for bridge construction in some other similar engineering.