51704144), and Talent Project of Revitalizing Liaoning Funding Project (Grant no. 2017YFC1503101), Natural Science Foundation of China (Grant no. LJ2017QL037), National Key R&D Projects (Grant no. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.ĭata Availability: All relevant data are within the manuscript and its Supporting Information files.įunding: This work was supported by the Discipline Innovation Team of Liaoning Technical University (LNTU20TD08) Department of Education of Liaoning Province (Grant no. Received: Accepted: JPublished: August 26, 2021Ĭopyright: © 2021 Zhang et al. PLoS ONE 16(8):Įditor: Antonio Riveiro Rodríguez, University of Vigo, SPAIN The NBSS model is useful for studying the evolution of stress and displacement fields of complex surrounding rock mass, which provides important theoretical guidelines for the support design and stability analysis of soft rock tunnel engineering.Ĭitation: Zhang J, Yao B, Ao Y, Jin C, Sun C (2021) Analysis and numerical calculation of a coupled creep and strain-softening model for soft rock tunnels. The distribution of the plastic zone calculated by the NBSS model is larger with more localized fractures. We use the NBSS and nonlinear Burgers Mohr-Coulomb (NBMC) models to calculate the plastic zone distribution characteristics and deformation law. The accelerated creep curve obtained by the numerical calculation is consistent with the experiments, which verifies the model reliability. The experimental results show that the viscoplastic parameters and post-peak softening parameters of mudstone are highly sensitive to confining pressure and exhibit nonlinear characteristics. The nonlinear elastic-viscous model is used to simulate the steady creep behavior of mudstone, and the nonlinear viscoplastic strain-softening model is used to simulate the accelerated creep behavior and post-peak strength attenuation behavior. We present a coupled nonlinear Burgers strain-softening (NBSS) model and numerical calculation method to investigate the coupled effects of creep and strain-softening of soft rock tunnels.
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Proper mechanical model selection is critical in tunnel support design and stability analysis, especially to reflect the creep and strain-softening behavior of soft rock.