Modeling progressive damage and failure of rock under continuous cyclic loading considering strength degradation of mesoscopic finite elements

摘要

The failure process of rock materials submitted to cyclic loadings such as drilling, excavation, and external vibration, constitutes the mechanism of some underground excavation instability. However, there still does not exist a well-established numerical method for modeling progressive damage and failure of rock subjected to cyclic loading-unloading and assessing or predicting the impact of cyclic loading on the stability of rock engineering. The primary objective of this study is to introduce a new numerical model based on finite element code to numerically analyze the damage and failure process of rock under cyclic loading. An assumption of linear strength degradation of the mesoscopic elements was proposed by taking stress level, and upper and lower limit stresses into consideration. Then, it was implemented to iteratively calculate stress and strain fields after some loading-unloading cycles under the framework of RFPA2D (rock failure process analysis in two-dimension) code. To examine the reliability of the newly proposed model, simulations of cyclic loading tests for sandstone samples were numerically reproduced, and the results were validated with experimental data in the literature. The consistency between numerical and experimental results demonstrates that the proposed model, which considers the strength degradation of mesoscopic finite elements, albeit with several limitations, may have potential application in modeling rock damage and fracture under cyclic loading conditions.