摘要
横观各向同性层状岩体的Ⅰ型张拉断裂破坏作为岩土工程常见问题受到广泛关注,对其开展研究具有重要的科学意义。本文以岷县木寨岭隧道炭质板岩为研究对象,利用CCD高速相机搭建观测系统来开展不同层理状态下直缝半圆盘三点弯(SCB)试验,通过数字图像相关方法分析炭质板岩裂纹扩展表面位移场演化特征和断裂过程区,研究结果表明:炭质板岩试样在韧带仅为宽度0.4 mm的人工直缝尖端应力集中程度高,起裂易发生,导致相应峰值破坏载荷均较小,且断裂破坏呈显著脆性;炭质板岩层理对其张拉断裂特性显著影响,典型层理如ME,MD,MA型试样断裂韧度依次为0.195,0.097,0.168 MPa·m;通过数字方法揭示了试样裂纹起裂及断裂演化的拓展过程,断裂扩展路径受层理影响有显著差异;基于缝端口张开位移和缝尖表面位移场关系,提出了计算断裂过程区长度的简化方法,对比理论解结果较为接近,具有科学、合理性。
As a common problem in geotechnical engineering,type I tensile fracture failure of transversely isotropic layered rock mass has been widely concerned,and it is of great scientific significance to conduct research on it.In this paper,with carbonaceous slates of Muzhailing Tunnel in Minxian County as research object,an observation system was built with charged couple discharge(CCD)high-speed cameras to carry out semi-circular bend(SCB)tests under different bedding conditions.Evolution characteristics of surface displacement field of carbonaceous slate crack propagation and fracture process area were analyzed with digital image correlation(DIC).The results have shown that the stress concentration of carbonaceous slate sample is high at the tip of artificial straight seam with ligament width of only 0.4 mm,the initiation of crack is easy to cause the corresponding peak failure loads to be small,and the fracture failure is significantly brittle.The bedding of carbonaceous slate has a significant effect on its tensile fracture characteristics with the fracture toughness of typical beddings such as ME-type,MD-type,and MA-type samples are 0.195,0.097,0.168 MPa·m successively,revealing the process of crack initiation and fracture evolution of test sample,and that the fracture propagation path is significantly different due to the influence of bedding.Based on the relationship between the opening displacement of the crack tip and the displacement field of the crack tip surface,a simplified method was proposed for calculating the length of the fracture process zone close to theoretical solutions,which proves to be scientific and reasonable.
作者
李二强
冯吉利
朱天宇
张龙飞
张洪昌
LI Erqiang;FENG Jili;ZHU Tianyu;ZHANG Longfei;ZHANG Hongchang(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China;School of Mechanics and Civil Engineering,China University of Mining and Technology-Beijing,Beijing 100083,China)
出处
《采矿与安全工程学报》
EI
CSCD
北大核心
2021年第5期979-987,共9页
Journal of Mining & Safety Engineering
基金
国家重点研发计划项目(2016YFC0600901)
国家自然科学基金项目(41172116,U1261212)。
关键词
层理
炭质板岩
直缝半圆盘三点弯
断裂韧度
数字图像相关方法
变形位移场
断裂过程区
bedding
carbonaceous slate
semi-circular bend
type I fracture toughness
digital image correlation
deformation displacement field
fracture process zone
