Affiliation:
1. Department of Civil and Environmental Engineering, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong SAR, P.R. China
Abstract
Tunneling results in stress relief and arching in the ground. New tunnel excavation beneath an existing tunnel but at different angles can lead to different patterns of stress redistribution. Studies on multitunnel interaction have mainly focused on perpendicular tunnels, and the effects of tunneling skew angle remain poorly understood. Three-dimensional centrifuge modeling and numerical back-analyses were conducted to investigate the effects of twin-tunnel interaction at three skew angles (30°, 60°, and 90°). The effects of new tunnel excavation on an existing tunnel were simulated by controlling tunnel volume and weight losses in-flight. A hypoplastic soil model capable of simulating path-dependent and strain-dependent soil stiffness was adopted for the numerical back-analyses. Distinct load redistribution patterns were identified to explain deformations of the existing tunnel at different skew angles due to the advancement of the new tunnel. For 90° tunneling, hoop force increased at the crown and decreased at the left springline of the existing tunnel. The opposite responses were identified at 30° tunneling. A critical skew angle of 30° tunneling led to the maximum invert settlement and tunnel deformation of the existing tunnel. At 30° tunneling, the induced strain in the tunnel lining was 2.3 times larger than that of tunneling at 90°, exceeding the cracking limit suggested by the American Concrete Institute.
Publisher
Canadian Science Publishing
Subject
Civil and Structural Engineering,Geotechnical Engineering and Engineering Geology
Cited by
10 articles.
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