摘要
基于颗粒离散元方法,建立考虑页岩层理面强度和刚度弱化效应的页岩试样二维颗粒流数值模型。依据页岩室内三轴压缩试验所得的宏观力学参数随相对吸水率的演化规律,对数值模型中不同吸水时间条件下的细观参数进行标定,研究不同吸水时间下页岩岩样的卸荷力学特性和破坏特征。结果表明,加载和卸荷两种应力路径下的岩样强度参数均随吸水时间增加而减少,但卸荷路径下的黏聚力普遍小于加载条件,内摩擦角则相反;不同吸水时间下岩样主要发生沿层理面破坏及与层理面成一定角度的剪切破坏,随着吸水时间的增加,岩样的破碎程度明显提升,试样的破坏更容易受控于层理面,其破坏趋势也从单剪转化为双剪模式;不同卸荷阶段下岩样内部微裂纹数目的发展规律亦有所差异,在卸荷屈服阶段张、剪裂纹的增长产生分异,剪裂纹数量增长逐渐趋于平稳而张裂纹数量增长率持续增加,当到达峰后阶段应力残余点时张裂纹数量的增长速率明显降低并趋于平稳。
Considering the weakening effect of strength and stiffness of the shale layer,the two dimensional particle flow numerical models of shale specimens are established using the granular distinct element method.Based on the evolution law of the macroscopic mechanical parameters with the relative water absorption rate,which is obtained from the triaxial compression tests of shale specimens,the mesoscopic parameters of the numerical model under different water absorption time are calibrated,in order to study the unloading mechanical properties and failure characteristics of shale specimens under different water absorption time.The results show that the strength parameters under loading and unloading stress paths decrease with the increase of water absorption time.However,the cohesion is generally smaller in unloading condition compared with that of loading condition,while the internal friction angle presents an opposite law.Under different water absorption time,the rock samples mainly fail along or at a certain angle to the bedding plane.More fractures are found in the rock samples with the increase of water absorption time.Thus the failure modes of the samples,changing from single shear to double shear,are more easily controlled by the bedding planes.The development law on the number of microcracks in rock samples under different unloading stages is also different.The growth rate of tensile and shear cracks in the yield stage under unloading status is differentiated,showing that the growth rate of shear cracks gradually tends to be stable while that of tensile cracks continues to increase.When the stress residual point at the post-peak stage is reached,the growth rate of tensile cracks significantly decreases,and then basically tends to be stable.
作者
卞康
陈彦安
刘建
崔德山
李一冉
梁文迪
韩啸
BIAN Kang;CHEN Yan-an;LIU Jian;CUI De-shan;LI Yi-ran;LIANG Wen-di;HAN Xiao(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China;University of Chinese Academy of Sciences,Beijing 100049,China;Faculty of Engineering,China University of Geosciences,Wuhan,Hubei 430074,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2020年第S01期355-367,共13页
Rock and Soil Mechanics
基金
国家重点研发计划项目(No.2016YFC0401802)
国家自然科学基金重点项目(No.51539002)
国家自然科学基金项目(No.51779249)
湖北省自然科学基金项目(No.2018CFB632)
中国科学院大学生创新实践训练计划(2018年)
关键词
吸水时间
页岩
卸荷
破坏特征
颗粒流
water absorption time
shale
unloading
failure characteristics
particle flow
