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在进行土工试验时,土样端部摩擦效应和初始缺陷都可以引起试样的不均匀变形,进而形成宏观的剪切带。基于数字图像测量技术改进了GDS多功能三轴仪,进行砂土的固结排水三轴试验,获得了试样在不同时刻的应变等值线云图和局部应力-应变全曲线,研究了试样端部的摩擦效应。结果表明,端部摩擦显著地影响试样的力学特性,对径向应变的影响可达10%。通过在砂土试样中放置粉质黏土块的方法获得了宏观不均匀土样,并测试其剪切带的形成过程。测试结果表明,试样在两种材料的界面处形成不连续刚度,引起变形的不均匀发展,进而形成宏观的剪切带而破坏。
During the geotechnical test, the frictional effect and initial defects of the soil sample end can cause the uneven deformation of the sample, and then form the macroscopic shear band. Based on the digital image measurement technology, the GDS multifunctional triaxial apparatus was improved and the consolidation and drainage triaxial tests of sand and soil were carried out. The strain contour curves and local stress-strain curves at different time were obtained. End friction effect. The results show that the end friction significantly affects the mechanical properties of the sample, the radial strain of up to 10%. Macroscopically heterogeneous soil samples were obtained by placing silty clay blocks in sand samples and the formation of shear bands was tested. The test results show that the sample forms discontinuous stiffness at the interface between the two materials, causing the non-uniform deformation and then the formation of macroscopic shear bands.