Abstract
Tunnels commonly pass through inclined rock stratum, but research on the collapse of the rock surrounding the tunnels in inclined rock strata is currently underdeveloped. The purpose of this study was to predict the progressive asymmetrical collapse failure of deep-buried tunnels in inclined rock strata to decrease the risk of collapse during tunnel construction. We constructed a new two-dimensional progressive asymmetrical collapse failure mechanism for deep-buried tunnels in inclined rock layers to analyze their collapse failure characteristics with the help of the nonlinear Hoek–Brown yield criterion and the limit analysis theorem. The calculation equations of the range and total weight of the asymmetrical collapsing block in rectangular and circular tunnels were obtained via theoretical derivation. The validity of the proposed method in this work was verified by comparison with existing research. To discuss the impact of different parameters on the range and total weight of an asymmetrical collapsing block of the surrounding rock in inclined rock stratum, the range and total weight of the asymmetrical collapsing block of the most common rectangular and circular tunnels under the varied parameters are provided. The results of this study can provide useful support for practical tunnel construction and design.
Highlights
Due to unfavorable factors such as excavation disturbances or late support, tunnels with weak surrounding rock are prone to collapse
Many scholars have attempted to introduce various methods to analyze the stability of tunnels and predict tunnel collapse failure [1,2,3,4,5,6,7]
Mollon et al [2] provided design charts for the case of a frictional and cohesive soil by determining the surface collapse pressure of a circular tunnel driven by a pressurized shield based on a translational three-dimensional multiblock failure mechanism
Summary
Due to unfavorable factors such as excavation disturbances or late support, tunnels with weak surrounding rock are prone to collapse. Lee et al [1] conducted a series of centrifuge model tests and numerical simulations to investigate tunnel stability and arching effects in soft soils, and proposed the boundaries of the positive and negative arching zones. Zhang and Han [8] found that unfavorable factors such as rock weakening and large span caused a series of collapses in Longyou Cave in Zhejiang province, China through site investigations and laboratory tests, and proposed some effective measures to increase the safety of this cave, including slowing rock weathering. The kinematics of tunnel collapse were not considered in these studies, which does not reflect actual tunnel collapse mechanisms, and these methods are difficult to use widely in practical engineering
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