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宋飞, 张建民. 各向异性砂土渐近状态试验研究[J]. 岩土工程学报, 2010, 32(4).
引用本文: 宋飞, 张建民. 各向异性砂土渐近状态试验研究[J]. 岩土工程学报, 2010, 32(4).
Experimental study on asymptotic behaviour of anisotropic sand[J]. Chinese Journal of Geotechnical Engineering, 2010, 32(4).
Citation: Experimental study on asymptotic behaviour of anisotropic sand[J]. Chinese Journal of Geotechnical Engineering, 2010, 32(4).

各向异性砂土渐近状态试验研究

Experimental study on asymptotic behaviour of anisotropic sand

  • 摘要: 砂土的渐近力学行为是土的本构关系的重要研究内容之一。通过系列三轴排水剪切试验、三轴等向压缩试验和等应变增量比试验研究了砂土的各向异性及其对于渐近状态的影响。研究结果表明:在剪切变形较小时,砂土主要表现出压缩变形的各向异性,在剪切变形较大的条件下则表现为强度的各向异性;当沿着等应变增量比路径加载时,应力比最终趋于一个常数,即渐近状态的应力比;相对于沉积面水平的试样而言,沉积面铅直的渐近状态应力比稍大;在剪切变形较小时,各向异性砂土的渐近状态应力比与各向同性准则预测结果相差较大,当剪切变形较大时二者较接近。通过比较不同各向异性材料的等应变增量比试验结果研究了各向异性的程度对于渐近状态应力比的影响。在揭示各向异性砂土渐近状态的物理机制的基础上给出了定量描述渐近状态应力比随应变增量比变化的数学表达式。

     

    Abstract: Asymptotic behavior is one of the important mechanical characteristics of sand. Anisotropy and its effect on the asymptotic behavior of sand are investigated by use of a series of triaxial drained shear tests and strain paths tests. Studies show that when the ratio of lateral to axial strain increment is one, the axial stress isn’t equal to the lateral one, which can be called anisotropy of compression deformation. And anisotropic shear strength due to anisotropic alignment of particles can be seen clearly in the strain paths tests where the strain increment ratio is small enough to cause the soil failure. When the sand is loaded along the constant strain increment ratio paths, the ratio of lateral to axial stress will eventually approach a constant value, i.e. the asymptotic stress ratio. And the asymptotic stress ratio is a little larger for the specimens with vertical bedding plane than that with horizontal one. When the shear deformation of soil is small, the difference between the measured asymptotic stress ratio and that predicted by the isotropic asymptotic state criterion is large, but it gradually decreases with the increase of the shear deformation. The effect of anisotropy on the asymptotic stress ratio is investigated on the basis of strain paths tests on different anisotropic materials. Furthermore, the asymptotic behavior of anisotropic sand is discussed and an equation is formulated to quantitively determine the relationship between the asymptotic stress ratio and the strain increment ratio for anisotropic sand.

     

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