Kinematic analysis of the three-dimensional stability for tunnel faces by pseudodynamic approach

Abstract

Seismic waves have significant effects on the stability of geotechnical engineering projects. However, only a small number of studies have focused on the seismic stability of tunnel faces. Using the kinematic approach of limit analysis, this paper conducts a seismic analysis to evaluate the three-dimensional stability of the tunnel face. A three dimensional rotational mechanism is introduced to describe the active collapse of a tunnel face. To overcome the shortcomings of the conventional pseudostatic method, the pseudodynamic method, which can consider the variation in acceleration with time and space, is used to characterize earthquake acceleration. The collapse body is horizontally sliced into many layers considering the acceleration changing with space, and the work rate is calculated along the horizontal plane. Based on the kinematic analysis method, the explicit equation to calculate the required supporting pressure on the tunnel face is derived. The results can be obtained using the optimization algorithm. The validity of the proposed method is proven in comparison to that of existing solutions. Parameter analysis is further performed to reveal the effects of specific parameters on the retaining force.