A micro-macro dynamic compressive-shear fracture model under static confining pressure in brittle rocks
A micro-macro dynamic compressive-shear fracture model under static confining pressure in brittle rocks
复制标题
脆性岩石静围压下微观-宏观动态压剪断裂模型
DOI：
10.1016/j.ijimpeng.2018.07.010
复制
发表时间：
2018-12-01
影响因子：
5.1
通讯作者：
Qi, Chengzhi
中科院分区：
文献类型：
--
作者：
Li, Xiaozhao;Qi, Chengzhi
针对含有大量初始微裂纹的脆性岩石，提出了一种新的静围压下的动态压剪断裂模型。该模型的制定基于机翼裂纹模型、莫尔-库仑失效准则、裂纹-应变关系以及已建立的与轴向应变率相关的动态断裂韧性。裂纹-应变关系是通过关联微观和宏观损伤来获得的。通过结合裂纹-应变关系和与裂纹扩展速度相关的动态断裂韧性，建立了与轴向应变速率相关的动态断裂韧性。提出了描述峰前硬化阶段和峰后软化阶段的完整动态应力-应变本构关系。预测了应变速率对动态应力-应变关系、抗压强度、抗剪强度、内聚力和内摩擦力的影响。发现了一种新的临界应变率，使动态裂纹萌生应力等于动态压缩强度。超过这个临界应变率，动压强度、剪切强度、内聚力和内摩擦角都有较大的变化。还讨论了围压、裂纹尺寸、裂纹摩擦、裂纹倾角对高应变速率下动态应力-应变关系、抗压强度、抗剪强度、内聚力和内摩擦角的敏感性。通过实验数据的比较验证了所提出的压剪断裂模型的合理性。
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.