Three-dimensional back-analysis method for the mechanical parameters of the new ground ahead of a tunnel face

In order to evaluate the mechanical characteristics of the new ground ahead of a tunnel face, a three-dimensional back-analysis method is proposed. The values for the modulus of elasticity, Poisson’s ratio, and the six components of the initial stress levels of the ground are identified through the method. The method consists of an ordinary 3D finite element method and the secant method, and it is based on the iteration procedure. The accuracy of the results obtained by the method is verified through numerical calculations. The applicability and the simplicity of the method also support its usefulness.