【作者】 陈留凤；

【导师】 彭华；

【作者基本信息】 武汉大学 ， 工程力学， 2018， 博士

【摘要】 泥岩是深部地下工程常见地层,由于含有膨胀性矿物,与水膨胀效应显著。本文针对泥岩水力耦合特性,综合采用多种宏细观测试方法,开展了泥岩干湿循环试验,系统研究了其水力特性,并结合数值仿真方法,进行了研究,拟揭示泥岩的干湿变形和损伤演化机理,主要工作如下:(1)利用所研制的湿度-质量跟踪实验系统,实时跟踪干湿循环过程泥岩质量变化,研究了不同干湿循环梯度和次数对泥岩土水特征曲线影响规律,发现了干湿循环次数对泥岩土水特征曲线影响较大,并利用V-G模型,进行了定量分析;(2)提出一个二维扩散模型,反映了干湿循环过程泥岩水气交换过程,反演得到了泥岩的扩散系数。在低湿度环境下,水蒸气的扩散系数随着湿度增加而增加,当湿度达到98%又降低。结合核磁共振和水银压汞试验,研究了泥岩含水分布和孔隙结构分布特征;(3)利用数字图像相关技术和环境电子扫描显微镜,实现了泥岩干湿循环细观原位测试。通过开展不同干湿循环试验,研究了干湿循环次数和干湿循环梯度对泥岩变形和细观结构影响规律;(4)泥岩干湿变形呈现显著的非均质性、非线性、各向异性和不可逆性,通过细观图像定量分析,分别揭示了泥岩变形和损伤机理,确定出它与材料矿物组成和细观结构的内在关系;(5)通过数值仿真,模拟分析了含夹杂对泥岩干湿变形影响规律。结果表明,泥岩干湿变形,由于不同矿物组成的变形不协调性将产生应力集中,并导致了不同矿物界面产生微裂隙,形成损伤破坏;提出的泥岩水力耦合模型可以反映干湿循环过程中泥岩水气扩散和变形特征。更多还原

【Abstract】 Many structures of underground engineering are constructured in mudstone formation.Due to having clay minerals,mudstone exhibits a notable coupled hydro-mechanical behavior,particually swelling.In this paper,we will study the hydromehcanical behavior of the mudstone combining different macro-microscopic experimental and numerical methods to reveal the mechanisms of deformation and damage during drying and wetting.The main work is summaried as follows:(1)Develepment of a specific setup to follow the weight of the mudstone samples,the effect of cyclic hydration and dehydraiton on the soil water content curve will be analysied and quantified;the cyclic number of hydration and dehydraiton on the SWCC is notable and the latter will be fitted using the V-G model;the quantitifed anlaysis will be carried out;(2)Propose of a two-dimensional diffusion model to describe the hydration of the mudstone and characterization of the diffusion coefficition;the diffusion coefficient increases with the increase of relative humidity(RH)when RH is at low level,and it redecreases when RH reaches 98%;combining with NMR and MIP techniques,the water distribution and pore size of the mudstone will be analysied;(3)The deformation of the mudstone at multiscales will be identified combining ESEM and DIC techniques.The cyclic hydration and dehydration tests have carried out to investigate the cyclic number and hydric gradient on the hydric deformation and structure.The results show that the hydric deformation of the mudstone strongly depends on the hydric gradient and cyclic number of hydration and dehydration;(4)The hydric deformation of the studied mudstone exhibits notable heterogeneous,nonlinear and anisotropic and irreversible.The mechanisms of the heterogeneous,nonlinear and anisotropic deformation of the mudstone will be revealed by analyzing the microstructure change and component;(5)Using finite element method,the hydric deformation will be simulated.It is found the internal stress concentration will be created during during hydration and dehydration and it is due to the imcompatible deformation of the different components and such stress is the origine of the damage of the mudstone.更多还原