Failure Performance of 3DP Physical Twin-Tunnel Model and Corresponding Safety Factor Evaluation
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ORIGINAL PAPER
Failure Performance of 3DP Physical Twin‑Tunnel Model and Corresponding Safety Factor Evaluation Quan Jiang1 · Xiaopei Liu1,2 · Fei Yan1 · Yao Yang1,2 · Dingping Xu1 · Guangliang Feng1 Received: 27 February 2020 / Accepted: 1 September 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract Quantitative stability evaluation of multi-tunnel structure is an important issue related to the safety assessment and stable construction of geotechnical underground tunnels. In this work, the overall failure process of twin tunnels were exhibited by a physical simulation based on the 3D printing (3DP) sandstone analogues model, and a safety factor method was also presented for evaluating the general safety of multi-tunnel structure. For checking the 3DP material performance of physical model, uniaxial and triaxial compressions for the 3DP cylinder specimens were first tested and showed that their mechanical properties and failure characteristics were similar to natural rock in general. Then, the overloading tests for twin-tunnel model were carried out and have exposed the critical position of overall failure of twin-tunnel structure through visual observation and automatic measurement. Testing results and corresponding numerical back analysis indicated that the connectivity of plastic strain between tunnels can be deemed as the conservative instability criterion (i.e. yielding of material) and the inflection point of tunnels’ displacement can be deemed as overall failure criterion (i.e. structure failure) for twin-tunnel structure. The safety analysis for underground hydraulic caverns indicated that this method can provide a reference for quantitative and reasonable evaluation of the general safety of multi-tunnels or caverns and the local instability zone of surrounding rock. Keywords Twin tunnels · Safety degree · Physical model test · 3D print · Instability criterion
1 Introduction Multi adjacent tunnels or caverns widely exist in underground engineering, such as large caverns in hydropower stations (Tezuka and Seoka 2003; Zhu et al. 2010a; Plasencia et al. 2015; Broch 2016; Feng et al. 2019), twin tunnels of freeways and railways in both urban and mountainous areas (Suwansawat and Einstein 2007; Afifipour et al. 2011; Sharifzadeh et al. 2013; Merlini et al. 2018) and roadway groups in deep mines (Islam and Shinjo 2009; Zhu et al. 2014; Huang et al. 2018). The stability analysis of multitunnel structures (including caverns) is one of the key issues for avoiding engineering disasters during the design and construction of underground engineering. Affected by the * Fei Yan [email protected] 1
State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, China
University of Chinese Academy of Sciences, Beijing 100049, China
2
mutual influence of adjacent tunnels, the deformation and failure behaviors of multi-tunnel structures are more complex than those of a single tunnel. Currently, various meth
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