Prediction of mechanical parameters of the surrounding rock based on Hoek-Brown criterion

Abstract

The research object is F1-6, a branch of Nujiang fault zone, which is crossed by the diversion tunnel of a hydropower station in Southwest of China, the relationship between geological strength index (GSI), disturbance parameter (D) and acoustic wave velocity of rock mass is explored. The Hoek-Brown criterion based on wave velocity is applied to predict the mechanical parameters of the surrounding rock in F1-6.The feasibility of the method is verified by the in-situ test of the fracture zone (F1-6), and the deformation of tunnel after excavated is predicted by the numerical simulation method. The study show that the mechanical parameters of fault fracture zone predicted by Hoek-Brown criterionbased on wave velocity are close to the results of in-situ test. It is feasible to predict the mechanical parameters of deep fracture zone by this method, which can solve the difficulty that the mechanical parameters of deep fracture zone can not be obtained by test directly. In addition, the numerical simulation based on the derived mechanical parameters can provide guidance for the design and construction of tunnel engineering.