School of Resources and Safety Engineering,Chongqing University
State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University
School of Electrical and Control Engineering,North University of China

层状页岩受内部层理方位分布特征的影响,其力学性质常表现出明显的各向异性特征。为了探究层理方向对层状页岩Ⅰ型断裂特性的影响,针对不同层理倾角β、预制裂纹角度为0°的半圆盘试件开展三点弯曲静态压缩试验和数值模拟试验。试验结果表明,试件的Ⅰ型标准化应力强度因子YⅠ会随着层理倾角的变化呈现出明显的差异性,并与层理倾角呈现出良好的三次函数关系,且仅在层理倾角β为0°和90°时,试件表现为纯Ⅰ型断裂模式,即层理倾角的变化会改变试件的断裂模式。同时,试件的Ⅰ型断裂韧度随着层理倾角的增大而逐渐减小,并与层理倾角呈二次函数关系;当层理倾角与预制裂纹角度垂直时,试件的Ⅰ型断裂韧度最大;而当层理倾角和预制裂纹角度平行时,试件的Ⅰ型断裂韧度最小。另外,基于扩展有限元法(XFEM),对半圆盘层状页岩试件的破断机制进行研究,验证了试验和计算结果的准确性。

The mechanical properties of layered shales are usually anisotropic due to the influence of internal bedding azimuths. In order to explore the influence of bedding direction mode Ⅰ fracture characteristics, three point bending static compression tests and numerical simulation tests were carried out on half-disc specimens with precrack angles of 0° and different bedding dip angle β. The test results show that the mode Ⅰ standardized stress intensity factor of the specimen YⅠ varies significantly with the change of bedding angle,and presents a good cubic function relationship with bedding angle; only when the bedding angle β is 0° or 90°,the specimen shows a pure mode Ⅰ fracture mode,that is,the change of bedding angle will change the fracture mode of the specimen. At the same time, the mode Ⅰ fracture toughness of specimens decreases gradually with the increase of bedding angle, and presents a quadratic function relationship with bedding angle. When the bedding angle is perpendicular to the precrack angle,the mode Ⅰ fracture toughness of the specimen is the largest. When the bedding angle is parallel to the precrack angle,the mode Ⅰ fracture toughness of the specimen is the smallest. In addition,based on the extended finite element method(XFEM),the fracture mechanism of the half-disc layered shale specimen is studied,and the accuracy of the test and calculation results is verified.

国家重点研发计划青年科学家项目(2022YFC2905700);重庆市自然科学基金面上项目(cstc2020jcyj-msxmX0570);山西省基础研究计划面上项目(202203021221106);中央高校基本科研业务费项目(2020CDJ-LHZZ-004)

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LI Yong,HU Shuangjie,GUI Huigao,et al. Effect of bedding direction on mode Ⅰ fracture characteristics of precrack shale[J].Mining Safety & Environmental Protection,2024,51(1):1-6.