摘要
在单轴平面应变压缩条件下,采用FLAC模拟扩容角对具有初始随机材料缺陷的光滑端面岩石试样的破坏过程及对应力—应变曲线的影响。利用FISH函数于试样内部规定初始缺陷。密实的岩石服从莫尔库仑剪破坏与拉破坏复合的破坏准则,破坏之后呈现应变软化-理想塑性行为。缺陷在破坏之后经历理想塑性行为。扩容角较高时试样内部最终发生破坏的单元数目较多。随着扩容角的增加,剪切带变得粗壮和陡峭。扩容角对应力—轴向应变曲线影响不大。扩容角增加时,在应变软化阶段,应力—侧向应变曲线变平缓,根据作者过去提出的理论公式,这是由于剪切带宽度增加的贡献超过剪切带倾角增加的贡献所致。当扩容角较高时,应力峰值时试样内部的最大剪切应变增量较高,因而试样破坏的前兆比较明显。剪切带倾角的数值结果与Arthur倾角比较接近,未能超过Coulomb倾角。扩容角越大,剪切带最终可以获得越来越高的剪切应变和体积应变。
For rock specimen with smooth ends and with initially random material imperfections, the effects of dilation angle （DA） on the failure process and stress--strain curve were numerically modeled using FLAC in uniaxial plane strain compression. Using a written FISH function, the initial imperfections within the specimen were prescribed. For intact rock exhibiting linear strain-softening behavior beyond the occurrence of failure and then ideal plastic behavior, the failure criterion is a composite Mohr-Coulomb criterion with tension cut-off. Initial imperfection undergoes ideal plastic behavior beyond the occurrence of failure. Rock specimen with higher DA is subjected to severe failure in the final deformation stage. Wider and steeper shear bands are observed at higher DA. The effects of DA on the stress--axial strain curve can be neglected. Less steep stress--lateral strain curve at post-peak is expected at higher DA since the contribution of the increase in shear band width to lateral strain exceeds the contribution of the increase in shear band inclination according to an analytical expression proposed by Wang and coworkers. Higher DA leads to higher value of maximum shear strain increment within the specimen. Therefore, more apparent precursor to failure can be observed at higher DA. Shear band inclination is closer to Arthur theory and is lower than Coulomb theory. Higher DA results in higher values of shear strain and volumetric strain in shear band.
出处
《中国有色金属学报》
EI
CAS
CSCD
北大核心
2007年第7期1063-1071,共9页
The Chinese Journal of Nonferrous Metals
基金
国家自然科学基金资助项目(50309004)
关键词
非均质性
材料缺陷
扩容角
剪切带
轴向应变
侧向应变
前兆
heterogeneity
material imperfections
dilation angle
shear band
axial strain
lateral strain
precursor
