岩石初始宏观变形模拟及微裂纹闭合应力确定方法

Initial macro-deformation simulation and determination method of micro-crack closure stress for rock

为了建立能够反映岩石初始宏观变形模拟方法以及微裂纹闭合应力确定新方法,首先,针对岩石及其内部微裂纹的受力变形特点,将岩石视为由岩石基质和微裂纹两部分组成,并以此建立了岩石与其组成成分之间的变形分析模型,并由材料变形力学分析角度分别建立了岩石基质和微裂纹的受力变形分析方法,从而建立了岩石初始宏观本构模型并给出了模型参数的确定方法;然后,针对现有微裂纹闭合应力确定方法存在的缺陷与不足,提出了基于本文模型的微裂纹闭合应力确定新方法;最后,基于本文模型探讨了围压对岩石初始宏观变形非线性上凹程度的影响,从理论上阐述了围压效应即围压与岩石初始宏观变形非线性上凹程度成负相关。研究结果表明,本文模型不仅能够很好地模拟岩石启裂前变形全过程,还能够阐述岩石与其组成成分之间的变形关系;微裂纹闭合应力确定新方法既满足微裂纹闭合应力的理论意义又能够避免人为因素的干扰,并具有易操作性的特点,表明了本文模型与方法的合理性与可行性。

This study aims to establish a simulation method reflecting the initial macroscopic deformation of rock and propose a determining method for internal micro-cracks closure stress. Firstly, a deformation analysis model was established between rock matrix and micro-cracks, based on the stress and deformation characteristics of rock and its internal micro-cracks. Then deformation analysis methods were put forward for rock matrix and internal micro-cracks, respectively, according to the analysis of material deformation mechanics. Thus, an initially macroscopic constitutive model was deduced for rock, and its determining methods for the model parameters were also given. Secondly, a new method was proposed to obtain the closure stress of micro-cracks, due to the defects and deficiencies of those existing methods. Lastly, this study investigated the effect of confining pressure on the nonlinear concave degree of initially macro deformation of rock by using the established model. The theoretical result indicated that there was a negative correlation between them. Research results show that this established model can not only simulate the full deformation procedure of rock before failure, but also explain the deformation relationship between rock and their components. The new method can not only satisfy the theoretical significance of micro-cracks closure stress, but also avoid the interference of human factors. Moreover, this new method is easy to operate. Therefore, the above results verify the rationality and feasibility of the proposed model and method in this study.