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不同于常规土体单元试验中恒定围压的应力路径,进行了减围压(卸载)应力路径下丰浦砂的平面应变压缩试验,研究了初始围压和初始相对密度对砂土的剪切强度和剪切带特性的影响。结合二维数字图像(DIC)相关方法,分析剪切带的形成过程,对剪切带的厚度和倾角及其影响因素进行定量地分析。研究结果表明,剪切带形成于峰值剪切强度之前;对于密实丰浦砂试样,随着围压的增加,其剪切强度(最大有效主应力比)减小且峰值强度出现越晚,剪切带厚度减小而剪切带倾角变化不大;丰浦砂试样的相对密度越高,剪切强度越大且峰值强度出现越早,剪切带厚度越小而剪切带倾角越高。此外,基于峰值内摩擦角的Coulomb公式可以较好地预测平面应变试验条件下丰浦砂的最大剪切带倾角。
Different from the stress path of constant confining pressure in the conventional soil unit test, the plane strain compression test of Fengpu sand under the stress-relieving (unloading) stress path was carried out. The effects of initial confining pressure and initial relative density on the shear of sand Effect of strength and shear band characteristics. Combined with two-dimensional digital image (DIC) correlation method, the formation process of shear band is analyzed, and the thickness and inclination angle of shear band and its influencing factors are quantitatively analyzed. The results show that the shear band is formed before the peak shear strength. With the increase of the confining pressure, the shear strength (maximum effective principal stress ratio) decreases and the peak intensity appears later, The thickness of the shear zone decreases and the inclination of the shear zone does not change much. The higher the relative density is, the higher the shear strength is and the earlier the peak intensity appears. The smaller the shear zone thickness is, high. In addition, the Coulomb formula based on the peak internal friction angle can predict the maximum shear band inclination of Fengpu sand under the plane strain test.