Effect of Nonlinear Deformational Macrojoint on Stress Wave Propagation Through a Double-Scale Discontinuous Rock Mass
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ORIGINAL PAPER
Effect of Nonlinear Deformational Macrojoint on Stress Wave Propagation Through a Double‑Scale Discontinuous Rock Mass L. F. Fan1 · M. Wang1 · Z. J. Wu2 Received: 30 June 2020 / Accepted: 5 November 2020 © Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract The overall dynamic mechanical behavior of a double-scale discontinuous rock mass with a nonlinear deformational macrojoint was investigated. A method of combining the split three characteristic lines with the piecewise linear displacement discontinuity model (DDM) was proposed. The method was applied to investigate the transmission coefficient of P-wave propagation normally through a double-scale discontinuous rock mass with a nonlinear deformational macrojoint. The results were verified by comparison with the results of P-wave propagation normally through a double-scale discontinuous rock mass with a linear deformational macrojoint. The results showed that for a small amplitude stress wave, the nonlinear deformational macrojoint can be simplified as a linear deformational form to study the stress wave propagation, whereas for a large amplitude stress wave, the effects of the nonlinear deformational behavior of the macrojoint must be considered. The difference of the effects of nonlinear and linear deformational macrojoints on large amplitude stress wave propagation can be overlooked in the low-frequency or high-frequency regions. In addition, when the incident stress wave amplitude and initial macrojoint stiffness are sufficiently large, the effects of the nonlinear deformational macrojoint on stress wave propagation can be overlooked, and the effects of microdefects must be considered. The influence degree of microdefects on the stress wave propagation increases with the increase of incident stress wave frequency. Keywords Nonlinear deformational macrojoint · Microdefects · Split three characteristic lines · Piecewise linear DDM
1 Introduction The study of stress wave propagation in natural rock mass is of great significance for the dynamic stability of rocks. The discontinuities of microdefects and macrojoints that exist in rock mass significantly influence the stress wave transmission (Jaeger et al. 2007; Deng et al. 2012, 2014; Fan et al. 2020a; Wei et al. 2019). The microdefects cause viscoelastic behavior of the rock mass under dynamic loading (Fakhimi and Fairhurst 1994; Fan et al. 2013; Ichikawa et al. 2011; Niu et al. 2018; Wu and Shao 2019). On the other hand, the complete deformational behavior of filled macrojoints is generally nonlinear (Li 2013; Li et al. 2018a, b; Ma et al. 2011; Kulhawy 1975; Bandis et al. 1983; Barton et al. 1985), * Z. J. Wu [email protected] 1
College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China
State Key Laboratory of Water Resources and Hydropower Engineering Science, School of Civil Engineering, Wuhan University, Wuhan 430072, China
2
which makes the effective mechanical properties of a double-scale discontinuous rock mass
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