鉴于试验砂岩内摩擦角较大及峰后脆性强的特点，选用颗粒流程序PFC2D中的cluster单元进行模拟，在常规三轴压缩试验校正的基础上得到一组能够真实反映砂岩宏观力学行为的细观参数，模拟了砂岩两种卸围压路径，结果表明其峰值强度随初始轴向应力的增大而不断增大，其规律与试验相同。选取了两种卸围压路径微裂纹数目随应力-应变的演化趋势进行分析，结果表明卸围压对试样造成的损伤较加轴压大，同时初始轴向应力增大一定程度上增加了试样承受破坏的能力。通过对不同应力路径裂纹两侧位移场的分析可知卸围压会造成颗粒在横向产生位移不连续，导致试样破坏。

Cluster element in particle flow code (PFC2D) is used to construct numerical specimen in light of the large internal friction angle and brittleness at post-peak stage of tested sandstone. A set of micro-parameters that can reproduce the macromechanical behavior of sandstone were calibrated through comparing with the experimental results under triaxial compression. Then two different radial unloading paths are simulated. The numerically simulated results show that the peak strength increases with the increasing of initial axial stress, and has a similar trend with the experimental results. The evolution characteristic of microcrack numbers under two radial unloading paths is analyzed. The damage extent under radial unloading is more serious than that under axial loading. Furthermore, the ability to withstand damage enhance with the increasing of initial axial stress. From the analysis of displacement field under different loading paths, it is clear that sandstone fails due to the discontinuity of displacement.