Abstract
In the process of tunnel excavation, the cutter wear rate is accelerated when the tunnel boring machine (TBM) passes through the rock stratum and the cutter is commonly replaced frequently during the excavation. In the replacement stage, the stability of the excavation surface is crucial to the operation of the project. In this study, commercial software PLAXIS3D is adopted for the evaluation of the stability of the excavation surface by considering different scenarios. The Hoek–Brown failure criterion is adopted as the constitutive model for the rock in the numerical analysis. Various failure modes under different working conditions are obtained. The results from the numerical analyses indicate that the excavation surface during the replacement is stable for those different scenarios. The factor of safety (FoS) for the stability of the excavation surface varies from 2.88 to 14.04. The failure modes near the excavation surface can be divided into four types: (i) central inward invasion, (ii) bilateral inward invasion, (iii) sliding, and (iv) outward invasion. With the increase of support pressure, the safety factor increases first and then decreases.
Highlights
It is known that the geotechnical problems are commonly associated with shear failure of soil or rock
Most of the stability evaluations for the geotechnical problems are based on the failure criterion of soil or rock. e shear strength reduction method is commonly adopted by the numerical analysis and has received most attention in geotechnical engineering [1, 2]
Li et al [4] conducted the numerical analysis for the excavation work by adopting the shear strength reduction method
Summary
It is known that the geotechnical problems are commonly associated with shear failure of soil or rock. Most of the stability evaluations for the geotechnical problems are based on the failure criterion of soil or rock. E shear strength reduction method is commonly adopted by the numerical analysis and has received most attention in geotechnical engineering [1, 2]. Li et al [4] conducted the numerical analysis for the excavation work by adopting the shear strength reduction method. Lu et al [5] and Shi et al [6] adopted the shear strength reduction method to calculate the stability of excavation surface in the tunnel construction. Numerical analyses are conducted to evaluate the stability of the excavated rock surface by adopting the shear strength reduction method. The failure modes of the excavated rock surface are categorized and discussed
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