Abstract: The longitudinal deformation profile (LDP) can reflect the spatial effect of excavation face in tunneling. Most of the previous studies on LDP, however, ignore the influence of surrounding rock quality and stress level. Based on the Hoek-Brown failure criterion and the finite difference method, functions of LDP which can quantify the difference of spatial excavation effect are given. LDP with various surrounding rock qualities and stress levels can be calculated by using these functions. By means of an error analysis, and by comparing with other equations, the rationality and universality of the proposed method are shown. The results indicate that, when basic quality indices (BQ) of rock masses have the same value, LDP tends to become flatten as the tunnel depth increases, implying that the relaxation process of stress and displacement is slowing down. When tunnel depths are the same, LDP also tends to become flatten as the BQ decrease. These features of LDP behind the excavation face are even more salient compared to that at the front of the excavation surface. The longitudinal deformation at the excavation face depends also upon the surrounding rock quality and the stress level, and its maximum value is not more than 30% of the final longitudinal deformation.

Key words: tunneling engineering, longitudinal deformation profile, generalized Hoek-Brown failure criterion, surrounding rock quality