考虑损伤阀值影响的岩石损伤统计软化本构模型及其参数确定方法

DAMAGE STATISTICAL SOFTENING CONSTITUTIVE MODEL FOR ROCK CONSIDERING EFFECT OF DAMAGE THRESHOLD AND ITS PARAMETERS DETERMINATION METHOD

在基于Lemaitre应变等价性理论的岩石损伤模型基础上,首先探讨岩石应变软化变形过程中损伤变量或损伤因子的变化规律,并结合岩石应变软化变形全过程特征及其损伤机制的研究,探讨建立岩石损伤演化模型时考虑损伤阀值影响的必要性;其次,在对现有岩石微元强度度量方法研究的基础上,提出可考虑损伤阀值影响的新型岩石微元强度度量方法,并引进统计损伤理论,建立可考虑损伤阀值影响的岩石统计损伤演化模型,该模型不仅能反映损伤阀值的影响,而且能反映岩石损伤程度受应力状态影响和岩石损伤在不同应力状态下损伤起始点不同的特性;再次,在此基础上,建立能充分模拟岩石应变软化变形全过程的损伤统计本构模型,并提出其参数确定方法,该模型不仅能充分反映岩石在低应力水平或变形较小时的线弹性变形特性,而且模型参数物理意义明确,适用于复杂应力状态情况;最后,通过工程实例分析,验证了该模型的合理性。

Based on rock damage model founded by Lemaitre＇s strain equivalent theory, the changing rule of damage variable or damage factor during the process of rock strain softening deformation, the characteristics of rock strain softening, the rock damage mechanism and the necessity of considering the influence of the damage threshold in developing rock damage evolvement model are discussed. Then, a new method for measuring microcosmic element strength of rock is presented with consideration of damage threshold; and a new statistical damage evolvement model is established by adopting statistical damage theory. This model can reflect not only the influence of damage threshold but also the influence of stress states on damage degree of rock as well as the damage characteristics of different initial points under different stress states. Based on these, a damage statistical softening constitutive model used to simulate the rock strain softening deformation process is developed; and the method to determine the model parameters is proposed. This model can reflect the linear-elastic characteristics of rock deformation in low stress level or small deformation. Moreover, the concepts of the model parameters are clear; and it is convenient for the model to be applied to complex stress state cases. Finally, the case study indicates that the constitutive model is reasonable.