Analysis of Face Stability Based on Incomplete Soil Arching Effect

Abstract

The excavation face stability is a critical issue in the analysis of the tunneling disturbance to the surrounding environment, in which the soil arching effect is a phenomenon that cannot be ignored. Based on the wedge-prism model, this study proposed a slice method to calculate the limit support pressure, taking into account both the vertical soil arching effect of the prism and the horizontal arching effect of the wedge. In addition, the rotation of the principal stress was introduced to improve the lateral stress ratio on the vertical sliding faces including the wedge and the prism, in which two new trajectories of the major principal stress were recommended, based on a previous numerical study. Furthermore, the contribution of the incomplete soil arching effect was discussed in this study, assuming that there was a function between the effective internal friction angle of the soil and the tunnel cover depth. Through the comparison of the results with theoretical and numerical models, the improved model was validated and showed agreement with them. Finally, parameters related to the limit support pressure were thoroughly investigated to provide a better understanding of the proposed model.