基于颗粒流的砂岩三轴破裂演化宏-细观机理

发布时间：2018-02-24 00:47

本文关键词： 砂岩三轴压缩试验颗粒流数值试验细观分析裂纹演化围压　出处：《煤炭学报》2017年S1期 　论文类型：期刊论文

【摘要】：以重庆地区砂岩的三轴压缩试验应力-应变曲线为基准,完成了二维颗粒流PFC~(2d)数值砂岩试样的细观参数标定。针对0.5~20 MPa围压下数值砂岩在双轴试验中的宏观力学响应,从试样内部位移、3种类型裂纹(总裂纹、拉裂纹和剪裂纹)的数目演化和角度分布等细观层面进行了解释。研究结果表明:PFC~(2d)数值试样能代表物理砂岩的主要宏观力学特性;试验过程中,试样内3种裂纹数目均呈"S"型累积,其突变点与宏观应力-应变曲线的弹、塑和破坏特征点对应;随着围压增大,由试验过程中剪裂纹始终占主导逐渐变为拉裂纹始终占主导,拉裂纹的占比逐渐增大;对于整个试样和破裂带,破裂带内拉裂纹的占比始终高于整个试样;总裂纹和剪裂纹角度分布的主方向明显,与加载方向相同;拉裂纹的角度分布较为均匀,在加载方向、破裂面及共轭破裂面方向的集中度相对明显。
[Abstract]:Based on the stress-strain curve of triaxial compression test of sandstone in Chongqing area, the meso-parameter calibration of two-dimensional granular flow (PFC) / 2d) numerical sandstone sample has been completed. The macroscopic mechanical response of numerical sandstone under 0.5 ~ 20 MPa confining pressure in biaxial test has been studied. The number, evolution and angular distribution of three types of cracks (total crack, tensile crack and shear crack) within the specimen are explained. The results show that the numerical specimen can represent the main macroscopic mechanical properties of the physical sandstone. During the test, the number of the three kinds of cracks in the specimen is "S" type accumulation, and the abrupt point corresponds to the elastic, plastic and failure characteristic points of the macroscopic stress-strain curve, and with the increase of confining pressure, During the test, the shear crack always dominates and the tensile crack always dominates, and the proportion of the tensile crack increases gradually, and for the whole specimen and the fracture zone, the percentage of the tensile crack in the fracture zone is always higher than that in the whole specimen. The main direction of the angular distribution of total crack and shear crack is obvious and the direction of tensile crack is the same as the direction of loading, and the angle distribution of tensile crack is relatively uniform, and the concentration of the direction of loading direction, fracture surface and conjugate fracture surface is relatively obvious.
【作者单位】：重庆交通大学土木工程学院;重庆交通大学山区桥梁与隧道工程国家重点实验室培育基地;
【基金】：国家自然科学基金资助项目(51308574) 重庆市科委基础与前沿研究基金资助项目(cstc2014jcyj A30023) 重庆市教委科学技术研究基金资助项目(KJ1400310)
【分类号】：TU45

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