摘要
采用含张开型表面裂隙辉长岩试样,对单轴压缩荷载作用下预制裂隙的破裂模式进行一系列试验研究。试验结果表明:预制裂隙的破裂模式是以一种新的方式——反翼裂隙(其扩展方向是与翼裂隙方向相反的)模式为主的,且新生裂隙的起裂位置并不在预制裂隙的端部。翼裂隙只在试验的后期出现。预制裂隙倾角对试样的起裂应力影响较为显著,当60°≤α≤75°时,试样的起裂应力约为辉长岩抗压强度σc的75%;当30°≤α≤45°时,试样内部轴向应力值接近辉长岩抗压强度σc的90%时,预制裂隙才起裂。反翼裂隙扩展角为135°～145°,当反翼裂隙扩展长度达到预制裂隙长度的1/2时,其扩展方向基本与加载方向一致。裂隙扩展过程的声发射(AE)定位结果与试验观察结果是一致的,这表明反翼裂隙是张开型表面裂隙三维破裂模式的主要特征,反翼裂隙属于局部劈拉应力作用下的压张性裂隙(模式V),其扩展的具体理论机制目前还不清楚,值得进一步研究。此外,当预制裂隙倾角在45°附近时,试样起裂后极易发生爆裂现象,说明原生裂隙的倾角也许是影响岩爆现象的一个重要参数。
A series of experimental studies are carried out to investigate the propagation of an open surface-flaw in gabbro samples under compression load.A new fracture pattern is observed where an anti-wing crack（its growth direction is opposite to that of wing crack）is induced at a distance away from the flaw tip in the region of compression stress zone.The wing crack appears at the later stage.Besides,the stress for crack initiation is strongly affected by the inclined angle α of the pre-existing flaw.The stress for crack initiation decreases when the flaw angle increases（30°≤α≤75°）.Besides,the outburst phenomenon always appears at the flaw tips when the flaw angle equals about 45°,which may be an important parameter for the problem of the rock outburst.The initiation angle of the anti-wing crack is between 135°and 145°from the flaw plane.The growth of the anti-wing crack turns to the loading direction when the crack growth length equals about half of the flaw length.The results of acoustic emission（AE）support the observations from the experiments.The anti-wing crack pattern can be observed in all the specimens containing an open surface-flaw.However,the growth mechanisms of the anti-wing crack are not fully investigated up to now.A further study would be carried out in the future.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2007年第3期525-531,共7页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(50579033
90510019)
国家重点基础研究发展规划(973)项目(2002CB412705)
香港理工大学科研基金项目(A-PE31
G-T419)
关键词
岩石力学
表面裂隙
翼裂隙
反翼裂隙
破裂模式
单轴压缩
rock mechanics
surface flaw
wing crack
anti-wing crack
fracture pattern
uniaxial compression
