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扩容现象是岩石变形破坏过程中的重要特征。基于MTS815 Flex Test GT岩石力学试验平台,采用室内三轴卸荷试验和塑性力学理论分析,揭示了大理岩在卸荷条件下的扩容特征及能量变化特征。结果表明,随着围压的增大,岩样的各特征应力随之增大,其扩容特征随之减弱;岩样的扩容参数——扩容指标以及剪胀角均具有围压效应,即扩容指标与围压呈良好的指数型分布,剪胀角与应力比呈线性分布;岩样的卸荷破坏过程中能量特征为初始时以可释放应变能为主到破坏时的耗散能为主,其间的转折点为初始损伤扩容点,同时卸荷条件下的特征能量值与围压具有良好的指数类型关系;在峰值点与残余点处,岩样的能量损伤值与剪胀角以及能量特征值与扩容指标均存在着较好的指数类型关系。
Dilatancy phenomenon is an important feature in the process of rock deformation and destruction. Based on the MTS815 Flex Test GT rock mechanics test platform, indoor triaxial unloading test and plastic mechanics theory analysis are conducted to reveal the dilatancy characteristics and energy variation characteristics of marble under unloading conditions. The results show that with the increase of confining pressure, the characteristic stress of the rock sample increases with the increase of its compressive strength, and its dilatancy characteristics decrease. The dilatancy parameters of the rock specimen, dilatancy index and dilatancy angle all have the confining pressure effect, The index and confining pressure showed a good exponential distribution with a linear distribution of dilatancy angle and stress ratio. The energy characteristics of the rock specimen during the unloading failure process were primarily energy dissipation mainly from releaseable strain energy to failure , And the turning point during this period is the initial damage expansion point. At the same time, the characteristic energy value under unloading condition has a good exponential relationship with the confining pressure. At the peak point and the residual point, the energy damage value, dilatancy angle and energy characteristic There is a good exponential relationship between value and capacity expansion.