基于三维离散元软件PFC3D模拟灰岩三轴压缩试验,研究试验过程中试样的变形、裂隙的发展以及破坏方式.通过数值模拟的位移场结果,可以直观地观察宏观断裂面的形成,围压较小时,试样发生局部的脆性破坏,而围压较大时,以试样的整体剪切破坏为主.三轴压缩破坏过程是能量耗散与释放的综合过程:初始加载阶段,外界输入能量主要转化为试样的可释放应变能,当超过储存极限时,试样产生破坏;中后期外界输入的能量主要转化为耗散能,用于试样内部微裂隙的产生、裂隙的发展、局部脆性破坏以及宏观断裂面的产生,最终导致试样整体破坏.试验结果表明,试样破坏时吸收的总能量和耗散能与围压有很强的线性关系,其线性拟合结果对于灰岩三轴压缩试验过程中的能量变化规律研究有一定意义.
The paper simulated limestone triaxial compression test based on DEM software PFC 3D ,and studied the specimen deformation ,cracks development and the way of failure during the test .The formation of macroscopic fracture surface can be visually observed by the numerical simulation results of displacement field .When the confining pressure is small,specimens will have partial brittle failure ,and when the confining pressure is large ,specimens will have over-all failure .The test process of triaxial compression failure can be seen an integrated process of energy dissipation and release.The energy of the external input is converted to strain energy of the sample in the initial loading phase .The sample will produce damage when energy exceeds the storage limit .The late energy of the external input is converted to dissipation energy mostly ,which lead to generation of internal micro-cracks,cracks development ,local brittle failure and macroscopic fracture surface ,and the sample will be destructed at last .The results show that the total energy ab-sorbed during the failure in the test and dissipation energy have a strong linear relationship with the confining pres -sure,and the linear fitting result is useful for the study of energy distribution rules during the limestone triaxial com-pression test .
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