含两组交叉节理砂岩强度及破坏特征离散元分析

为研究含两组交叉节理岩体强度及破坏特征，采用一组经室内试验标定的砂岩细观参数，建立含两组交叉节理岩体颗粒流模型，进行单轴压缩和三轴压缩模拟。基于模拟结果，分析了节理数量、节理倾角和围压对含两组交叉节理岩体强度及破坏特征的影响。结果表明：① 与完整岩石相比，节理岩体强度明显降低。峰值强度随着节理数量的增加近似线性减小，随着节理倾角的增大呈先减小后增大非线性变化趋势，而随着围压的增大而提高；② 节理岩体表现为张性破坏、沿节理滑移破坏、穿节理剪切破坏、张性滑移破坏及剪切滑移破坏等5种破裂模式；③ 节理数量增加会加剧试样破坏程度，但不改变其破裂模式。单轴压缩下，当节理倾角较小时主要发生张性破坏，随着倾角的增大，表现为张性剪切或沿节理面滑移破坏。在围压作用下，试样表现为剪切破坏或剪切滑移破坏。最后从细观层面探讨了节理岩体宏观裂纹的细观位移场分布特征。

Discrete element study on strength and failure behavior of jointed sandstone with two sets of cross-joints

In order to study the strength and failure behavior of jointed rock mass with two sets of cross-joints,a set of micro-parameters in particle flow code (PFC) calibrated by brittle sandstone specimen laboratory experiment results was used to set up a jointed rock mass model with two sets of cross-joints model.Then PFC was applied to investigate the mechanical behaviors of jointed rock mass under uniaxial and triaxial compression.On the basis of the simulated results,the influences of joint number,joint angle and confining pressure on strength characteristic and failure mode were analyzed in detail.The main findings can be described as follows:① Compared with the intact rock specimen,the peak strength of jointed rock mass with two sets of cross-joints decreases obviously.The peak strength decreases linearly with the increase of joint number,while it first decreases and then increases as joint angle increases.Furthermore,the peak strength is lager when confining pressure is lager.② Five typical failure modes,i.e.axial tensile failure,sliding failure along joint plane,shear failure through joint plane,mixed tensile and sliding failure and mixed sliding and shear failure are observed for jointed rock mass under uniaxial and triaxial compression.③ With the increase of joint number,its failure mode doesn’t change,but failure extent increases.When joint angle is small,axial tensile failures occur,while sliding along joint plane failure or mixed tensile and sliding failure comes up when joint angle is big under uniaxial compression.With confining pressure,shear failure or mixed sliding and shear failure becomes the main failure mode.Finally,the displacement distribution characteristic to reveal the meso-mechanism of macro-cracks coalescence was discussed.