Improved Nishihara model and its application in describing rock accelerated creep behavior

作者：Jun Hu, Junxin Shi, Shuai Zhang, Shangjun Zhao, Zhaokui Sun · 发表于：Geomechanics and Geoengineering · 年份：2025 · DOI：10.1080/17486025.2025.2537286 · 被引用次数：2 · 研究领域：Rock Mechanics and Modeling、Landslides and related hazards、Geotechnical Engineering and Analysis

This study presents an enhanced Nishihara model for precisely describing rock creep under three-dimensional stress, emphasising the accelerated creep phase. Unlike the classical model-which combines elastic, viscoelastic, and viscoplastic elements but poorly captures nonlinear acceleration under high stress-the revised version adds a strain-activated nonlinear Newtonian component. We derive its 3D constitutive equations and calibrate parameters using sandy mudstone creep tests. Results show the modified model accurately reproduces initial, steady-state, and accelerated creep, outperforming the original formulation. Sensitivity analysis highlights the influence of deviatoric stress and nonlinear viscosity on creep evolution. Fitting additional data from granite and sandstone confirms the model’s versatility across rock types. These improvements enhance predictive accuracy for engineering applications, including tunnel-surrounding-rock collapse risk assessment.