Abstract
Understanding the creep behaviours of rocks is essential for the long-term stability of underground excavations in mining engineering. Creep behaviours are more important when the mining depth is greater, which leads to the emergence of weak rock masses and high in situ stresses. In this study, the creep behaviours of argillaceous sandstone (AS) were systematically investigated. For the experimental investigation, creep tests were conducted on AS with different confining pressures (3, 6, 9, 12, 15, and 18 MPa) using an MTS815.02 rock mechanics test system. The mechanical characteristics of AS were analysed. For the numerical study, a nonlinear creep model of AS under equal and different confining pressures was established based on rock creep theory and plastic theory. The results showed that confining pressure could effectively improve the creep failure strength of AS, accelerating its creep deformation rate and process and reducing the final expansion volume. The nonlinear creep model was embedded in the FLAC3D software, and the experimental and numerical results agreed well. The experimental investigation and proposed creep model can provide important guidance in underground mines for safe long-term stability of underground excavations.
Highlights
The long-term behaviors of rock masses around underground structures have received increasing attention from both academia and industry since these behaviors have significant influence on the structures’ stability [1,2,3]
After the rock samples were collected in accordance with the International Society for Rock Mechanics (ISRM) recommendations for rock mechanics tests, the samples were processed deform at a high deformation rate
After the rock samples were collected in accordance with the International Society for Rock Mechanics (ISRM) recommendations for rock mechanics tests, the samples were processed into cylindrical specimens with a diameter of 50 mm and and aa height height of of 100
Summary
The long-term behaviors of rock masses around underground structures have received increasing attention from both academia and industry since these behaviors have significant influence on the structures’ stability [1,2,3]. The investigation of the creep behaviors of rock can be categorized into experimental studies and numerical modelling. Experimental studies are often performed using creep tests on various rock types and under various conditions, such as different confining pressures and temperatures [12]. Despite many investigations on the mechanical properties of argillaceous sandstone (AS), the creep behaviors of AS under different confining pressures have not been well documented. Numerical modelling is another way to analyze the creep behaviors of rocks. Jia proposed a nonlinear elastic viscoplastic damage model based on the modified Mohr–Coulomb criterion and investigated the creep and permeability of clay rock during the construction of a high-level waste repository [24]. Major rock creep models only stay at the stage of theoretical explanation, this paper embeds the constructed creep model into numerical calculation software to verify its correctness
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