考虑弹塑性应力渗流耦合作用的泥岩本构模型研究

发布时间：2018-05-03 15:56

本文选题：Boom + Clay　；参考：《长江大学》2017年硕士论文

【摘要】：泥岩是同时具有较低的渗透性、良好的蠕变特性、高吸附性以及遇水损伤自修复特性的富含粘土矿物,而Boom Clay继承了泥岩的上述特性的同时还有较好的膨胀性,使得Boom Clay地层具备非常好的化学封闭性,因此被比利时、法国、瑞士、德国等欧洲国家一致认定为处置核废料的最佳地层之一。为了能更确切的了解泥岩各地层不同的原位物理力学特性,欧洲内的数国均开展了地下实验项目,以对其进行系统的研究。本文结合比利时HADES地下实验室项目,对Boom Clay的弹塑性力学特性和应力-渗流耦合特性进行了研究,主要的研究内容如下:(1)对Boom Clay的地层分布、矿物组成颗粒粒径分布等基本物理参数进行了分析,结果表明:Boom Clay地层分布较为均匀;颗粒组成中,粒径小于32μm和小于62μm的居多;Boom Clay的矿物成分中粘土矿物占比大约在60%左右,这些粘土矿物包括伊利石、蒙脱石和高岭石;非粘土矿物主要为石英和长石组成。(2)对Boom Clay的室内三轴试验数据进行了分析,发现Boom Clay具有明显的峰前硬化和峰后软化力学特性,利用全应力-应变过程中的应变变化,建立了内变量,以此为参考,提出了能考虑应变硬化、软化的弹塑性耦合模型,并利用有限元软件ABAQUS对该模型进行了验证。验证结果发现,利用该模型所计算出的结果能够较贴切的反映Boom Clay在实际三轴压缩过程中的变形特征。(3)对Boom Clay在压缩变形过程中的渗透率演化规律进行了系统的分析,通过参考其他不同岩石在全应力-应变过程中的渗透性演化规律,并结合文中所建立的内变量将Boom Clay的渗透率演化过程分为三个阶段:扩容前的降低阶段、扩容后的极速增长阶段、达到残余阶段后的稳定阶段。为能充分考虑扩容点对渗透率突变的影响,引入了逾渗理论,在逾渗理论的基础上,结合围压与初始渗透率和峰值渗透率的关系,建立了能考虑围压效应的Boom Clay渗透率演化方程。(4)结合所建立的Boom Clay弹塑性耦合模型和考虑围压效应的Boom Clay渗透率演化方程,建立了Boom Clay应力-渗流耦合模型,利用USDFLD接口将模型嵌入到ABAQUS中,利用该模型对Boom Clay的三轴压缩试验进行了模拟,通过分析结果对该模型中的渗透率演化特征进行了验证。(5)基于Boom Clay各项物理力学参数、考虑应力-渗流耦合特征的Boom Clay模型等研究成果,结合比利时HADES地下实验室的CONNECTING GALLERY项目,建立Boom Clay地层中的盾构法巷道开挖有限元模型,对巷道开挖过程中的围岩应力、变形、和渗流特征变化进行模拟分析,为Boom Clay地层中的巷道开挖提供围岩的稳定性分析依据。
[Abstract]:Mudstone is rich in clay minerals with low permeability, good creep property, high adsorption and self-repairing property of water damage, while Boom Clay inherits the above characteristics of mudstone and has good expansibility. The Boom Clay formation has very good chemical closure, so Belgium, France, Switzerland, Germany and other European countries are unanimously recognized as one of the best formations for the disposal of nuclear waste. In order to better understand the different in-situ physical and mechanical properties of mudstone, several countries in Europe have carried out underground experiments to study them systematically. In this paper, the elastic-plastic mechanical properties and stress-seepage coupling characteristics of Boom Clay are studied in conjunction with the HADES underground laboratory project in Belgium. The main research contents are as follows: 1) stratigraphic distribution of Boom Clay. The basic physical parameters, such as particle size distribution of mineral composition, are analyzed. The results show that the formation distribution of Clay is relatively uniform, and the clay minerals account for about 60% of the mineral composition of the mineral particles smaller than 32 渭 m and less than 62 渭 m, respectively, and the distribution of clay minerals is about 60% in the mineral composition of Bom Clay, which is smaller than 32 渭 m and less than 62 渭 m. These clay minerals, including Illite, montmorillonite and kaolinite, and non-clay minerals, mainly composed of quartz and feldspar, are used to analyze the laboratory triaxial test data of Boom Clay. It is found that Boom Clay has obvious mechanical properties of pre-peak hardening and post-peak softening. Based on the strain variation in the process of total stress-strain, an elastic-plastic coupling model which can take strain hardening and softening into account is proposed and verified by the finite element software ABAQUS. The results show that the calculated results of the model can reflect the deformation characteristics of Boom Clay in the actual triaxial compression process. The permeability evolution law of Boom Clay during compression deformation is analyzed systematically. The permeability evolution of Boom Clay is divided into three stages by referring to the evolution law of permeability of other rocks in the whole stress-strain process and the internal variables established in this paper. After the expansion of the extremely rapid growth phase, the residual stage of stability after the stage. In order to fully consider the effect of expansion point on permeability catastrophe, the percolation theory is introduced. On the basis of percolation theory, the relationship between confining pressure and initial permeability and peak permeability is combined. The Boom Clay permeability evolution equation considering confining pressure effect is established. The Boom Clay elastic-plastic coupling model and the Boom Clay permeability evolution equation considering confining pressure effect are established. The Boom Clay stress-seepage coupling model is established. The USDFLD interface is used to embed the model into ABAQUS. The model is used to simulate the triaxial compression test of Boom Clay. The permeability evolution characteristics in the model are verified by the analysis results. The model is based on the various physical and mechanical parameters of Boom Clay. Considering the Boom Clay model of stress-seepage coupling characteristics and combining with the CONNECTING GALLERY project of HADES underground laboratory in Belgium, the finite element model of tunnel excavation with shield method in Boom Clay stratum is established. The stress and deformation of surrounding rock in the excavation process of roadway are analyzed. The stability analysis of surrounding rock is provided for roadway excavation in Boom Clay stratum.
【学位授予单位】：长江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD315

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