Uniaxial creep test and three-dimensional numerical simulation of double flawed sandstone with different rock bridge angles

To analyse the influence of rock bridge angle α on the strength and failure characteristics of rock mass under different stress paths，seven kinds of double flawed sandstone samples with differentα were prepared，then uniaxial compression tests，single and multi-stage creep tests were carried out. Results show that the rock bridge angleα has significant effect on the critical stress，but the ratio of the critical stress of the same sample is less affected by α . The long-term strengthσL of the samples is very close to the crack initiation stress σ ci ，thus the long-term strength of the rock mass can be estimated only through the conventional compression test. In terms of crack propagation，the penetration characteristics of the same samples under the four loading paths are basically the same：the rock bridge is not penetrated when the samples withα = 0°–45°are damaged，while the samples with α = 60°–90°show the mode of direct penetration failure of the rock bridge. It is shown that the influence of α on the crack propagation is greater than that of the stress path. In addition，some samples also show the phenomenon that the apparent crack and the internal crack propagation are not consistent. In view of this，based on the continuous medium element simulation，a crack propagation judgment method based on plastic strain was proposed，and a three-dimensional model was established for calculation. The simulation results show that they are consistent with the test results. This method is more accurate than the traditional method of judging the crack propagation through the plastic zone，and can provide some reference for the three-dimensional time-dependent propagation simulation of rock fracture. © 2023 Academia Sinica. All rights reserved.