Transverse extent of numerical model for deep buried tunnel excavation

• Published in: Tunnelling and underground space technology Vol. 84; pp. 373 - 380
• Main Authors: Su, Kai, Zhang, Yan-Jun, Chang, Zhi-Hui, Wu, He-Gao, Wang, Tao, Zhou, Wei
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.02.2019; Elsevier BV
• Subjects: Boundary conditions; Computer simulation; Convergence; Excavation; Finite difference method; FLAC3D; Mathematical models; Model extent; Numerical analysis; Numerical model; Numerical prediction; Plane strain; Rock masses; Three dimensional models; Tunnel construction; Tunnel excavation; Tunnels; Model extent; FLAC3D; Tunnel excavation; Numerical model
• ISSN: 0886-7798; 1878-4364
• DOI: 10.1016/j.tust.2018.11.034

•The influence of the transverse extents of numerical model on tunnel convergence is studied.•A comprehensive function of transverse extents to yield the minimum transverse section area with a given error is proposed.•The universal suggestion of numerical model transverse extents for deep buried tunnel are presented. Numerical simulation has been widely used for predicting rock mass convergence during tunnel excavation. Considering that tunnel construction is a three-dimensional (3D) process, the 3D numerical analysis, instead of the plane-strain models, are commonly employed in engineering practice. As the 3D numerical analyses require large numbers of computational resources, the geometric extents are often kept to a minimum to reduce simulation time. However, there is a lack of published information concerning appropriate the size of numerical model. The study investigates how the transverse range of tunnel section, including the upper boundary, the lower boundary and the lateral boundary, affects the tunnel convergence via the finite difference software package FLAC3D, respectively. Then, a comprehensive function to yield the minimum transverse section area within a given error is proposed. After several cases with different categories of rock are employed in the simulations, the universal model extents with the minimum transverse section area are proposed.