Research on the Mechanical Properties and Damage Constitutive Model of Multi-Shape Fractured Sandstone under Hydro-Mechanical Coupling

作者：Ying Zhang, Xu Wu, Qifeng Guo, Zhaohong Zhang, Meifeng Cai, Limei Tian · 发表于：Minerals · 年份：2022 · DOI：10.3390/min12040436 · 被引用次数：6 · 研究领域：Rock Mechanics and Modeling、Drilling and Well Engineering、Landslides and related hazards

In this paper, mechanical property tests of sandstone with multiple shapes of prefabricated fractures (single, T-shaped, and Y-shaped fractures) are carried out through the MTS815 rock mechanics testing machine and the Teledyne ISCO D-Series Pumps system. Considering the hydro-mechanical coupling effects, the experiments reveal the key thresholds, strength characteristics and deformation laws of multi-shape fractured sandstones during the progressive failure process. According to the elastic-plastic theory, the continuous damage theory and the statistical damage theory, a new damage model is constructed, which fully reflects the coupled effects among water, micro flaws and macroscopic prefabricated fractures. The crack closure stress σcc, crack initiation stress σci and damage stress σcd of multi-shape fractured sandstone samples are determined by the proposed volumetric strain response method. In the range of 0–90°, the σcc and σci of the multi-shape fractured sandstone samples are different, as well as the angles when the σcd and peak strength (σc) reach their peak values. The stress ratios (the σcc/σc, σci/σc, and σcd/σc are collectively referred to as stress ratios) are hardly affected by the shape and inclination of the fractures inside the rock. According to strength analysis and deformation characteristics, the weakening effect of water has less of an influence on the strength than prefabricated fractures. The stress–strain curve obtained, based on the hydro-mechanical...