【作者】 焦黎杰；

【导师】 胡再强；

【作者基本信息】 西安理工大学 ， 岩土工程， 2009， 硕士

【摘要】 本文以国家自然科学基金项目：黄土二元介质模型及其对剪切带形成的试验与数值模拟研究为依托,对黄土剪切破坏过程中宏观物理力学现象和细观结构演化过程,在水、力两种荷载作用下分别进行了应力式直接剪切增湿试验和三轴-CT固结排水剪切试验研究,为揭示黄土剪切破坏结构演化机理提供了详实的试验资料。应用改制的四联应力式直剪仪,进行了四个固结压力下不同剪应力水平一次性浸水饱和与剪应力水平0.3不同增湿浸水量的湿剪试验。得到了湿剪位移和竖向变形随时间的变化曲线,对比分析了剪应力水平、固结压力和增湿浸水量对湿剪位移和竖向变形演化规律的影响。同时,在湿剪位移变形稳定后,继续进行了原状黄土后湿应力式直接快剪试验,得到了不同剪应力水平和不同增湿含水量对黄土后湿抗剪强度影响的演化规律。并且根据释放结构势定义综合结构势参数的思想,基于原状黄土和扰动黄土湿剪变形量定义了黄土的水敏结构性参数m。。综合分析认为,m。具有较高的合理性、灵敏性和研究黄土水敏结构性的优越性。在后勤工程学院-南郑医院-CT-三轴科研站,进行了干密度和含水量相同的原状黄土与扰动黄土四个围压下三轴固结排水CT实时扫描剪切试验,得到了黄土剪切破坏过程中大量的CT图像和CT数据。从宏观物理力学特性——偏应力-轴向应变-体积应变关系曲线,结合CT扫描图像,CT数和方差,感兴趣域(ROI)等细观结构变化规律,综合分析了原状黄土和扰动黄土三轴剪切过程中,应变软化型、应变硬化型试样剪切破坏的演化机理。并通过增加试样含水量的相同三轴-CT试验,对比分析了黄土各剪切破坏型式演化规律的正确性。最后,在对岩土破损力学深入学习分析的基础上,基于CT数方差定义了原状黄土破损结构势参数mf,并对mf进行量化处理得破损率b。绘制破损率b与轴向应变、偏应力关系曲线,并进行代入围压σ。的归一化拟合,建立了原状黄土三轴剪切软化型结构破损演化方程。更多还原

【Abstract】 In this paper, the National Natural Science Foundation Project:Loess binary medium model and its implications for the formation of shear bands experiment and numerical simulation study based on the loess macroscopic shear failure process of physical and mechanical phenomena and microstructural evolution, in the water, power load of two separately conducted direct shear stress-type humidifier-CT test and triaxial consolidation undrained shear test study to reveal the structure of loess shear failure mechanism of evolution provides a detailed test data.Application restructuring of tetralogy of stress-type direct shear device, carried out the consolidation under the pressure of the four different shear stress level of one-time water saturation and shear stress level of 0.3 different amount of humidifying water wet shear test. By the wet shear displacement and vertical deformation curve changes with time, comparative analysis of the shear stress level, consolidation pressure and the amount of humidifying water wet shear displacement and vertical deformation of the impact of evolution. At the same time, in the wet shear deformation displacement and stability, the continued stress of loess after the wet-style fast direct shear test, the shear stress of different levels and different water content of loess humidifier after wet shear strength of the effects of evolution. According to the release of the structure and potential definition of potential parameters of the integrated structure of thought, based on the disturbance of loess and loess defined shear deformation of loess water-sensitive structural parameters. Comprehensive analysis of the view that the reasonableness of high sensitivity and research loess water-sensitive structural superiority.College of Engineering in Logistics-Nanzheng hospital-CT-triaxial research stations, carried out the same dry density and water content of loess and loess disturbance four triaxial confining pressure drainage consolidation in real-time CT scanning shear test has been loess shear failure process of a large number of CT images and CT data. From a macro-physical and mechanical properties-deviator stress-axial strain-the relationship between volumetric strain curve, combined with CT scan images, CT number and the variance, the domain of interest (ROI) such as micro-structural changes in the law, a comprehensive analysis of the loess and the disturbance loess triaxial shear process, the strain-softening type, strain-hardening type specimen shear failure mechanism of evolution. And by increasing the water content of the same specimen triaxial-CT test, comparative analysis of the loess type of shear failure of the correctness of evolution.Finally, in the broken rock and soil mechanics-depth study based on the analysis, based on the CT number variance is defined loess damaged the structure of potential parameters, and to quantify the rate of treatment was broken b. Drawing breakage rate b and the axial strain, deviatoric stress curve, and on behalf of finalistsσ3 pressure normalized fitting, set up a loess-type structure of triaxial shear softening damage evolution equation.更多还原