Three-dimensional face stability analysis of twin circular tunnels in double-layered soil based on semidefinite programming of adaptive node-based smoothed upper bound finite element limit analysis
Year: 2025
Type: article
Abstract: A new problem, i.e., face stability of horizontal and vertical twin circular tunnels in homogeneous double-layered soil is analyzed using a novel method proposed in this paper, adaptive 3D NS-UBFELA, i.e., three-dimensional node-based smoothed upper bound finite element limit analysis incorporating adaptive mesh refinement. In adaptive 3D NS-UBFELA, because of high computational efficiency but low accuracy offered by linear tetrahedral elements, the node-based strain smoothing technique is introduced into three-dimensional upper bound finite element limit analysis using linear tetrahedral elements to improve accuracy while ensuring efficiency. A new semidefinite programming (SDP) model is established based on the Mohr–Coulomb yield criterion. In adaptive mesh refinement, to achieve maximum solution accuracy for a given computational effort, volumetric strain rate is innovatively taken as the posteriori error indicator, and Octasection refinement is innovatively combined with limit analysis to locally refine elements marked by a newly proposed criterion. Adaptive NS-UBFELA is then verified and used to analyze the new problem. Results show that for vertical twin circular tunnels in two different layers of soil respectively, when the cohesion or friction angle of the first layer of soil is respectively equal to or greater than that of the second layer of soil and the cover depth of the upper tunnel is less than a certain value, volumetric strain rate only exists near the lower tunnel face. As the cover depth of the upper tunnel increases, volumetric strain rate of the upper tunnel face increases from zero, the overall stability of vertical twin circular tunnels decreases, and the minimal support pressure on tunnel faces increases.
Source: Computers and Geotechnics
Authors: Peng-Yu Li, Xiangsheng CHEN
Institution: Shenzhen University
Language: English
Subfield: Safety, Risk, Reliability and Quality
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,640
OpenAlex ID: W4416521677