In order to study the mechanical behavior of fractured rock mass with different apertures in the process of uniaxial compression, based on a set of micro-parameters that are calibrated by laboratory experiment of fractured sandstone specimen, a modified Rigid Body Spring Method ( RBSM) is used to simulate the failure process of jointed rock with different fracture aper-tures. The results show that with the increase of fracture apertures, the peak strength of jointed rock mass firstly increases and then decreases, but finally maintains stability. The failure modes of jointed rock mass with different fracture apertures are catego-rized into 3 types according to the initiation position of the micro crack. Furthermore, we reach a conclusion that the ultimate fail-ure is essentially caused by tension stress no matter what type of the failure mode is. As axial strain continues to rise, the develo-ping rate of micro cracks within the specimen gradually increases, however the number of shear cracks is far less than the tension cracks. Finally, the meso-mechanism of micro cracks initiation is revealed by the evolution of the displacement field.%为了研究不同张开度裂隙岩体单轴压缩过程中的力学特性，以裂隙试样室内试验结果标定岩体细观参数，采用改进刚体弹簧元法对不同张开度裂隙试样压缩破坏过程进行数值模拟。结果表明：试件峰值强度随着裂隙张开度的增大表现出先增大后减小，最后维持稳定的规律；根据微裂纹起裂位置，将不同张开度裂隙岩体破坏模式总结为3类，并得出最终失稳破坏本质上都是由张拉所致的结论；随轴向应变增加，试件内部微裂纹的发育速度逐渐提高，但剪切裂纹数量远小于张拉裂纹；最后通过位移场演化规律从细观层面揭示了微裂纹开裂的力学机理。
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