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在室内和现场试验的基础上,根据泥岩的非线性蠕变变形特点,构造了基于摩尔-库仑准则的蠕变势,建立了泥岩非线性蠕变损伤本构模型及其损伤演化方程;对泥岩裂隙自愈合机制进行了探讨,得到围压、孔隙水和饱水时间是影响裂隙愈合的主要因素,通过引入愈合应力和水化学愈合因子的概念,建立了泥岩渗透性自愈合模型。研究结果表明,泥岩非线性蠕变是其内部结构损伤在蠕变过程中的综合表现,泥岩的蠕变速率不仅与应力水平、时间相关,而且还与累积蠕变变形密切相关,提出的模型能较真实反映泥岩蠕变变形过程、损伤演化、渗透性演化和裂隙自愈合,且材料常数较少,便于从实验数据中获得。文中涉及到的数值算法、程序实现、模型参数的确定以及工程应用将在本文的Ⅱ部分给出。
Based on the laboratory and field tests, the creep potential based on the Mohr Coulomb criterion is constructed according to the nonlinear creep deformation characteristics of mudstone. A nonlinear creep damage constitutive model of mudstone and its damage evolution equation are established. The self-healing mechanism of fractures is discussed. Confining pressure, pore water and time of saturated water are the main factors that affect fracture healing. By introducing the concept of healing stress and chemical healing factor, a self-healing model of mudstone permeability is established. The results show that the nonlinear creep of mudstone is a comprehensive manifestation of the damage of its internal structure in the creep process. The creep rate of mudstone is not only related to stress level and time, but also to the cumulative creep deformation. The proposed model energy More accurately reflect the mudstone creep deformation process, damage evolution, permeability evolution and fracture self-healing, and less material constant, easy to get from the experimental data. The numerical algorithm involved in the paper, the realization of the program, the determination of the model parameters and the application of the project are given in Section II of this paper.