Abstract In this study, for an expressway tunnel project crossing the secondary fault of the Xiaojiang active area, a finite element model of tunnel dislocation-seismic motion response is established based on the wave theory and the numerical analysis method and taking into consideration the interaction between surrounding rock, structure and fault. The model is used to study the mechanical response characteristics of the tunnel support structure system under different seismic intensities on the basis of the existing reverse fault dislocation, and further analyze the influence law of the width of the fault fracture zone, fault dip and the quality of hanging-wall and footwall rock mass on the structural mechanical response. The results show that under the action of reverse fault dislocation-seismic motion, the lining structure damage first appears at the wall foot in the fault fracture zone, and the stress and the displacement of the lining wall foot change greatly, and the damage is more serious. Under the identical dislocation and seismic intensity, the distribution range of severe damage at the wall foot is 2-4 times those of other typical parts,and the wall foot and the fault fracture zone are the most unfavorable parts for fortification. As the seismic intensity increases, the width of the fault zone decreases, the dip of the fault increases, and the quality difference between hanging-wall and footwall of rock mass and the surrounding rock in the fractured area increases. The degree of lining damage and distribution range significantly increase, and the stress concentration is intensified. The fluctuation of stress amplitude rises, and the residual stress after the earthquake and the displacement abrupt change of the fault dislocation surface become more obvious.
Abstract：
In this study, for an expressway tunnel project crossing the secondary fault of the Xiaojiang active area, a finite element model of tunnel dislocation-seismic motion response is established based on the wave theory and the numerical analysis method and taking into consideration the interaction between surrounding rock, structure and fault. The model is used to study the mechanical response characteristics of the tunnel support structure system under different seismic intensities on the basis of the existing reverse fault dislocation, and further analyze the influence law of the width of the fault fracture zone, fault dip and the quality of hanging-wall and footwall rock mass on the structural mechanical response. The results show that under the action of reverse fault dislocation-seismic motion, the lining structure damage first appears at the wall foot in the fault fracture zone, and the stress and the displacement of the lining wall foot change greatly, and the damage is more serious. Under the identical dislocation and seismic intensity, the distribution range of severe damage at the wall foot is 2-4 times those of other typical parts,and the wall foot and the fault fracture zone are the most unfavorable parts for fortification. As the seismic intensity increases, the width of the fault zone decreases, the dip of the fault increases, and the quality difference between hanging-wall and footwall of rock mass and the surrounding rock in the fractured area increases. The degree of lining damage and distribution range significantly increase, and the stress concentration is intensified. The fluctuation of stress amplitude rises, and the residual stress after the earthquake and the displacement abrupt change of the fault dislocation surface become more obvious.
ZHAO Daneng1 WANG Yi2 REN Zhihua3
.Mechanical Response Analysis for Tunnel Structure Considering the Interaction of Fault Dislocation and Seismic Motion[J] MODERN TUNNELLING TECHNOLOGY, 2023,V60(4): 95-105
2023, Vol. 60 