原状Q2黄土结构损伤演化的细观试验研究

利用和CT机配套的多功能土工三轴仪，对原状Q2黄土在三轴剪切过程中内部结构的变化进行了动态、定量和无损的量测，得到了软化破坏土样内部结构演化的CT图像和相应的CT数据，从细观上解释了软化破坏过程。试验结果表明，原状Q2黄土内部存在大量孔隙、裂隙、姜石等结构缺陷，初始损伤明显且具有各向异性。原状Q2黄土软化破坏细观变形可大致分为4个阶段，即微压密阶段，损伤开始阶段，损伤快速发展阶段和损伤减缓发展阶段。剪切过程呈现以局部变形为主的细观变形特点，但整体上CT数减小，方差增大。用CT数和方差均可较好的描述原状Q2黄土软化破坏的损伤演化规律，随着含水率和固结围压的增大，CT数和方差变化率越小。

Meso testing research on structure damage evolution of natural Q2 loess

The interior structure change of natural Q2 loess in the process of tri axial shear test was monitored nondestructively by means of computerized tomography(CT) technology. The clear CT images and relevant data reflecting the structure evolution of softening failure samples were attained. The cause of softening failure was explained. The test results show that some structure damages such as pores, crevices as well as stiff lumps exist in natural Q2 loess. The initial damage of Q2 loess is obvious and inhomogeneous. The meso deformation of softening failure can be divided into four stages: slightly condensed stage, initial damage stage, damage rapidly developing stage and steady damage developing stage. The meso deformation in test process is manifested by local deformation. Generally, the CT number decreases and variance of CT number increases in the process of test. It is suitable to adopt CT number or variance of CT number to describe the structure damage evolution of natural Q2 loess. Following the increase of water content and confinement pressure of consolidation the change rates of CT number and variance tend to decrease.