层理方向对含预制裂纹页岩Ⅰ型断裂特性的影响
Effect of bedding direction on mode Ⅰ fracture characteristics of precrack shale
李勇 1胡双杰 2桂辉高 2孙传猛 3甘涛 2李银2
作者信息
- 1. 重庆大学 资源与安全学院,重庆 400044;煤矿灾害动力学与控制国家重点实验室,重庆 400044
- 2. 重庆大学 资源与安全学院,重庆 400044
- 3. 中北大学 电气与控制工程学院,山西 太原 030051
- 折叠
摘要
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.
Abstract
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.
关键词
页岩/层理方向/Ⅰ型断裂/断裂韧度/扩展有限元法/裂纹扩展Key words
shale/bedding direction/mode Ⅰ fracture/fracture toughness/XFEM/crack extension引用本文复制引用
基金项目
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(cstc2020jcyjmsxmX0570)
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)
出版年
2024
NETL
NSTL
万方数据