A micro-macro dynamic compressive-shear fracture model under static confining pressure in brittle rocks

作者：Li, Xiaozhao; Qi, Chengzhi^*

来源：International Journal of Impact Engineering, 2018, 122: 109-118.

DOI：10.1016/j.ijimpeng.2018.07.010

• Brittle rocks
• Micro-macro dynamic model
• Strain rate
• Dynamic compressive-shear fracture properties
• Static confining pressure

A new dynamic compressive-shear fracture model under static confining pressure is proposed in brittle rocks containing numerous initial microcracks. The formulation of this model is based on the wing crack model, the Mohr-Coulomb failure criterion, the crack-strain relation, and the established dynamic fracture toughness relating axial strain rate. The crack-strain relation is obtained by correlating the micro-and macro damages. The dynamic fracture toughness relating axial strain rate is established by combining the crack-strain relation and dynamic fracture toughness relating crack growth speed. The intact dynamic stress-strain constitutive relationship describing pre-peak hardening phase and post-peak softening phase is presented. The effects of strain rate on dynamic stress-strain relationship, compressive strength, shear strength, cohesion and internal friction are predicted. A novel critical strain rate making the dynamic crack initiation stress equal dynamic compressive strength is found. Exceeding this critical strain rate, the dynamic compressive strength, shear strength, cohesion and internal friction angle have a larger change. The sensitivities of confining pressure, crack size, crack friction, crack inclination angle on dynamic stress-strain relationship, compressive strength, shear strength, cohesion and internal friction angle under high strain rate are also discussed. Rationality of this proposed compressive-shear fracture model is verified by comparing the experimental data.

• 出版日期2018-12
• 单位北京建筑大学