摘要
基于岩石试件的卸荷试验,研究卸荷条件下岩石的变形、参数及破裂特征。研究结果表明:(1)卸荷过程中岩石向卸荷方向回弹变形较为强烈、扩容显著,脆性破坏特征明显。(2)卸荷过程中岩石的变形模量E逐渐减小,泊松比μ逐渐增大,E减小了5%～27%,而μ增大了50%～335%,变化均随初始围压的增大和卸荷强度的增强而增大,两者均与体积应变相关。(3)相对于加载试验,卸荷岩石的c减小而φ增大,且卸荷强度愈强,c减小得越多,φ增大的程度越小。峰值c减小了33.2%～47.8%,而残余c为正常值的65.3%～77.6%,峰值φ增加了14.7%～33.2%,而残余Φ增大了5.9%～9.4%。(4)卸荷条件下岩石破坏具有较强的张性破裂特征,各种级别的张裂隙发育,双向卸荷时甚至在次卸荷方向上也可能出现张拉裂隙,剪性破裂面一般追随张拉裂隙发展。
Based on unloading tests of rock samples, the deformation, parameters and fracture features of rocks under unloading are studied. The test results show that： （1） The characteristics of intense rebound deformation, distinct dilatancy and brittleness failure of rocks are all shown in the process of tmloading. （2） Deformation modulus E gradually decreases and Poisson ratio μ increases in the process of unloading. The deceasing amount of E is 5%-27%, while μ increasing 50%- 335%. The variables all increase with initial confining pressure increasing and unloading intensity, which are related with volumetric strain. （3） The cohesion c decreases but the internal friction angle φ increases relatively with the loading tests, and both are less with unloading intensity. The peak value of c decreases 33.2% - 47.8%, and remains normal value of 65.3% - 77.6%; peak value of φ increases 14.7% - 33.2%, and remains normal value of 5.9% - 9.4%. （4） The fracture is characterized by strong tensile, and all tensile cracks are fully developed, showing hypo-unloading when the rock samples are unloaded in two directions; and the shear fractures expand following tensile cracks.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2008年第11期2205-2213,共9页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金雅砻江水电开发联合研究基金重点项目(50539050)
重庆大学人才引进基金
关键词
岩石力学
三峡花岗岩
卸荷试验
变形特征
力学参数
破裂机制
rock mechanics
Three Gorges granites
unloading test
deformation feature
mechanical parameters
fracture mechanism
