不同围压和倾角砂泥岩互层岩样力学特性研究

Study on Mechanical Properties of Sand-Mudstone Interbedded Rock Samples with Different Confining Pressures and Dip Angles

为研究砂泥岩互层岩样的力学特性,首先通过室内试验获取砂岩和泥岩的力学参数,然后采用PFC^(2d)软件对砂岩和泥岩的微观参数进行标定,进而开展了不同围压和倾角条件下砂泥岩互层试件的三轴压缩数值试验,分析了围压、倾角对砂泥岩互层岩样力学性质和破坏特征的影响规律。结果表明:(1)相同围压下,随着岩层倾角的增加,抗压强度、弹性模量和黏聚力均为先减小后增大的变化趋势,在岩层倾角60°时为最小值,随着围压的增大,轴向应变也相应增大;(2)在试样加载过程中裂纹数量的突变点与应力应变曲线弹性、塑性和破坏特征点相对应,并且拉伸裂纹数量占总裂纹数的比例大于剪切裂纹的占比;(3)在岩层倾角和围压的影响下砂泥岩互层岩样的破坏模式可分为3种,即张剪破坏、顺层理面滑动的剪切滑移破坏、滑移破坏和张剪破坏同时存在的复合破坏。研究结论可为砂泥岩互层岩体相关工程的变形稳定分析提供参考。

In order to study the mechanical properties of the interbedded samples mass of sand and mudstone,the mechanical parameters of sandstone and mudstone were first obtained through laboratory tests,the microscopic parameters of sandstone and mudstone were calibrated by PFC~(2d) software,and then the sandstone-mudstone interceded rock samples were tested in triaxial compression numerial test under different confining pressure and dip angles conditions.The influences of confining pressure and dip angle on the mechanical properties and failure characteristics of sand-shale interbedded rock samples are analyzed.The results show that:(1) Under the same confining pressure,with the increase of the dip angle of rock formation,the compressive strength,elastic modulus and cohesion all tend to decrease first and then increase,and the minimum value is when the rock formation dip angle is 60°.As the confining pressure increases,the axial strain also increases accordingly.(2) The mutation point of the number of cracks during the loading process of the specimen corresponds to the elastic,plastic and failure characteristic points of the stress-strain curve,and the proportion of the number of tensile cracks to the total number of cracks is greater than that of shear cracks.(3) Under the influence of rock formation dip angle and confining pressure,the failure modes of sand-mudstone interbedded rock samples can be divided into three types:tension shear failure,shear slip failure along the bedding plane,slip failure and tension shear failure Simultaneous composite failure.The research conclusions can provide reference for the deformation and stability analysis of related engineering of sand-shale interbedded rock mass.