【摘要】 采用连续介质应变能理论分析蠕变宏观力学行为突变的过程,定义临界应变能密度值作为预测加速蠕变发生时刻的控制参数,采用西原正夫元件模型与Perzyna黏塑性理论相结合,考虑应力状态对加速蠕变的影响,用过屈服应力比函数反映加速阶段蠕变应变速率变化,建立了一种能描述蠕变3个阶段全过程的加速蠕变本构模型。该方法确定的加速蠕变时刻不仅能反映累积蠕变应变量的影响,而且能有效反映应力状态对加速蠕变的影响,为实现预测加速蠕变提供了可能,并且确定本构模型参数所需试验数量大大减少,为实际运用提供了方便。最后结合三轴蠕变试验,采用D-P屈服准则结合塑性流动法则,分析了不同流动法则对预测加速蠕变发生时刻的影响规律,数值模拟结果与试验数据基本吻合。更多还原

【Abstract】 The anthors analyzed the mutation process of the macro mechanical creep behavior from the perspective of the continuous strain energy theory,and defined the critical strain energy density to judge the occurrence time of accelerated creep. A accelerated creep constitutive model which can describe the whole process of transient creep,steady state creep,and accelerated creep was established by combining the Perzyna Visco-plasticity theory and Nishihara model,taking into account the influence of stress state on the accelerated creep and using the yield stress ratio to reflect the creep strain rate change of accelerated creep. The determined accelerating creep occurring time using this method not only reflectes the effect of cumulative strain of the creep,but also the influence of stress states on the accelerating creep,which provides possibility of prediction of the accelerating creep. In addition,the number of experiments to determine constitutive model parameters was significantly reduced,which is more convenient in practical applications. Finally,according to the triaxial creep test,the law that different flow rules affect the occurrence time of accelerated creep was analyzed by adopting Drucker-Prager yield criterion and plastic flow rule. As the simulation result is basically consistent with the test data,the research results provide a new method for the study of rock creep fracture process.更多还原