Total deformation prediction of the typical loess tunnels
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ORIGINAL PAPER
Total deformation prediction of the typical loess tunnels Yiguo Xue 1 & Xinmin Ma 1 & Weimin Yang 2 & Lei Ma 3 & Daohong Qiu 1 & Zhiqiang Li 1 & Xin Li 1 & Binghua Zhou 1 Received: 10 August 2019 / Accepted: 20 March 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The total deformation of loess tunnels is an essential basis for determining reasonable support timing, optimizing support parameters, and predicting collapses. Accurately predicting the total deformation is of considerable significance to the safe design and construction of loess tunnels. In this paper, a representative data sample set of the total deformation in loess tunnels was obtained using numerical simulations, and a back-propagation neural network (BPNN) was adopted. The input parameters were the bulk density, water content, elastic modulus, Poisson’s ratio, cohesion, internal friction angle of the loess, tunnel depth, and primary support strength. The output parameters were the total vertical and horizontal convergence deformation of the loess tunnel. The prediction results showed that the BPNN model could effectively predict the total deformation of a typical loess tunnel. Finally, the sensitivity analysis of the impact factors showed that the primary support strength and internal friction angle were parameters affecting the total deformation the most and least, respectively. This study can provide targeted guidance for the safe construction of loess tunnels. Keywords Loess tunnel . Total deformation . BPNN prediction model . Sensitivity analysis
Introduction In recent years, an increasing number of highways and railway tunnels have been built in loess areas. Because of loess’s unique characteristics, which include collapsibility, vertical joints, anisotropy, and macroporosity (Tan 1989; Liang et al. 2016; Mokritskaya et al. 2018), loess tunnels often cause geological hazards due to large deformations, such as vault cracking and cavern collapses. The deformation data of a tunnel is vital for judging the reliability of the tunnel supports and the stability of the surrounding rock. The majority of studies on the deformation laws of tunnels have been conducted through monitoring measurement analysis (Stiros and Kontogianni 2009; Bagherbandi 2016; Ma et al. 2018; Qiu et al. 2019), theoretical analysis (Rogers
* Daohong Qiu [email protected] 1
Geotechnical and Structural Engineering Research Center, School of Civil Engineering, Shandong University, Jinan 250061, China
2
School of Qilu Transportation, Shandong University, Jinan 250002, China
3
School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China
et al. 1994; Nishimura et al. 1999), numerical simulation (Li et al. 2016; Li et al. 2019; Zhang et al. 2020), and physical model tests (Qiu et al. 2017; Wan et al. 2019). The deformation of a loess tunnel can be divided into three stages: a rapiddeformation stage, a sustained-growth stage, and a slowgrowth stage, after which the tunnel tends to steady (Lai et
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