Risk Analysis of Tunnel Construction Scheme Change based on Field Monitoring and Numerical Analysis

Abstract

Because of the surrounding environment restriction, some sections of the Lanzhou Metro Line 2 were forced to change the original open excavation method to the concealed excavation method. Among them, the ingate is the transitional section connecting the shaft and the cross passage, which is accompanied by the force conversion of the structure during the plan change process, and accidents are prone to occur. Combining this project situation, a construction scheme for turning the shaft from the cross passage into the ingate of mine line was proposed, and the finite element software is used to simulate the scheme. Numerical analysis shows that the stability of the tunnel supporting structure, shaft, and cross passage all meet the design requirements. The final ground settlement caused by the proposed construction method is 7.1 mm, and the settlement of the vault is 11.97 mm. It also turns out that the proposed construction method causes less deformation, and the method can be applied to the construction of the ingate conversion. The rationality of the method and numerical model was further verified by the comparison between the monitored data of surface settlement and vault sinking and numerical simulation results. Finally, the modified concealed excavation method and the original open excavation construction method is compared. It is concluded that the concealed excavation method is superior to the original open excavation method in terms of construction schedule, construction safety, economic benefits, and impact of construction on the surrounding environment. It indicates that it is a good choice to replace the construction method early if necessary. The successful implementation of this project can provide a reference for the design and implementation of similar urban subway projects.

Application of the principal component analysis–cloud model in the assessment of the seismic stability of slopes

“…Many researchers (Zhou et al, 2018;Song et al, 2023) provided various methods to assess the seismic stability of slopes. The quasi-static or finite element methods for slope stability analysis are often adopted; for example, the critical problem of dynamic analysis of slope using FLAC3D was discussed in detail by Jing et al (2022); the dynamic factor of safety method was proposed by to provide the variation in the slope factor of safety with the time history of the earthquake; and some scholars have put forward a more suitable twopolar method to predict the seismic collapse of slopes (Gu et al, 2021).…”

Risk assessment of deep excavation construction based on combined weighting and nonlinear FAHP

“…Xu et al (2020) proposed a cloud model-based FAHP for risk assessment of tunnels. Moreover, Alireza et al (2021), Shahab et al (2020), Indrajit et al (2020, Guo et al (2022), Zhao et al (2021), Song et al (2021)and other researchers combined methods such as machine learning, Numerical simulation, and the N-K model with FAHP approach to broaden its application scope.…”