Damage Modeling and Hazard Index for Weakly Cemented Rock Using Energy Release Characteristics

Weakly cemented rock is a typical engineering material widely distributed in western China. The engineering disaster of weakly cemented rock is more complex than common granite and sandstone, and the effective surrounding rock support is difficult. It is of important significance for weak cementation geotechnical engineering to investigate the energy release behavior under various stress levels. In this study, the confining pressure effect of siltstone under triaxial compression was analyzed, and the rock energy release characteristics were studied using acoustic emission (AE) monitoring technology. The results indicate that the damage mechanical characteristics of weakly cemented rock are significantly different from those of granite, marble, sandstone. By analysing the AE b value and micro fracture surface, it is found that the dispersed secondary intergranular cracks of siltstone are constrained, under low stress level. Under high stress level, the mineral particles of siltstone extensively fracture, causing the release strongly of energy, and the b value fluctuates significantly. The energy release factor was introduced to modify the damage variable, then a damage constitutive model for weakly cemented rocks was established. Finally, the elastic energy release scale index was proposed to quantitatively characterize the hazard of weakly cemented rock engineering disasters under various stress levels.