Failure characteristics of sandstone specimens with randomly distributed pre-cracks under uniaxial compression
Failure characteristics of sandstone specimens with randomly distributed pre-cracks under uniaxial compression
复制标题
DOI：
10.1007/s12665-020-08933-4
复制
发表时间：
2020-04
影响因子：
2.8
通讯作者：
Hao Shi;Houquan Zhang;Lei Song;Z. Yang;G. Yuan;Xinran Xue;Yu Wang
中科院分区：
文献类型：
--
作者：
Hao Shi;Houquan Zhang;Lei Song;Z. Yang;G. Yuan;Xinran Xue;Yu Wang
以预裂纹数量（或密度）为变量，利用粒子流代码软件（PFC）研究随机分布的预裂纹对砂岩力学性能的影响以及相应的破坏过程。结果表明，随着预裂纹数量和总长度的增加，砂岩试件的无侧限抗压强度（UCS）近似呈负指数变化，而弹性模量则近似线性下降。随着预裂纹数量的增加，砂岩破坏对应的UCS和新裂纹数量均逐渐减少；另外，由于数据近似服从正态分布，新生裂纹的角度主要集中在90°左右。预裂纹越少的试件，分区破坏现象越明显。近水平预裂纹的上下均分布有应力屏蔽区，其尖端更容易存在集中应力。本文基于Mori-Tanaka方法建立了岩石损伤强度理论，通过引入预裂隙非均匀排列的密度系数η，可以很好地描述裂隙砂岩的演化强度。
Setting the number (or density) of pre-cracks as a variable, the effects of randomly-distributed pre-cracks on the mechanical properties and the corresponding failure process of sandstone are studied using Particle Flow Code software (PFC). The result shows that, as the number and total length of the pre-cracks increase, Unconfined Compressive Strength (UCS) of the sandstone specimen approximately shows a negative exponential variation, while the elastic modulus decreased near-linearly. With the increase of pre-crack number, both the UCS and the new crack number corresponding to the failure of the sandstone are gradually reduced; in addition, the angle of new cracks, as the data approximately obeyed the normal distribution, are mainly concentrated at about 90°. Partition damage phenomenon is more obvious for the specimen with less pre-cracks. And there are stress shielding region distributed above and below the near-horizontal pre-cracks, and the concentrated stress is more likely to exist at whose tips. The strength theory of rock damage is established based on the Mori–Tanaka method in this paper, by introducing a density coefficientηfor the non-uniform arrangement of pre-cracks, the evolution strength of cracked sandstone can be well-described.