Author(s)

T. Ishimoto & M. Kawahara

Abstract

In the case of tunnel excavation, it is important to investigate ground properties before staring construction. However, it takes much money and time to investigate the ground properties. Therefore, a numerical technique to solve the problem is proposed in this paper. The method is parameter identification, which is inverse analysis based on an optimal control theory. The main purpose of this research is to present the parameter identification of elastic modulus at the Kasakura tunnel site located in Fukui prefecture in Japan. The blasting is made at the tunnel face and the vibration of the blasting is measured at the observation points. These observation velocities are used for the performance function. Keywords: finite element method, parameter identification, first order adjoint method, weighted gradient method. 1 Finite element equation Applying the finite element method to the basic equation, the finite element equation discretized by the linear tetrahedral element is obtained as follows. In this paper, indecial notation and summation convention with repeated indies are used. The basic equation is expressed by the following three equations; the equilibrium of stress equation, the strain-displacement equation and the stressstrain equation. σij,j − ρbi + ρ¨ui = 0, (1) εij = 1 2 (ui,j + uj,i), (2)

Keywords

finite element method, parameter identification, first order adjoint method, weighted gradient method.