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为研究无黏性粗粒土直接剪切试验的强度尺寸效应,采用相同试样尺寸直剪仪对不同最大粒径无黏性粗粒土进行直剪试验。试验土料最大粒径分别为40、20、10、5和2 mm,各组土料具自相似质量分形结构以保证土料孔隙特征相同,并采用预先植入竖直锡丝的方法测量剪切带宽度。结果表明:随最大粒径增大,剪切带宽度和强度增大,且当最大粒径大于试样高度的1/20时,产生明显的强度尺寸效应现象;咬合力c和内摩擦角φ随试样高度与最大粒径比值的增大而减小,且与其对数呈明显的线性关系;随最大粒径增大,强度尺寸效应逐渐明显的原因为剪切带内颗粒数减少,颗粒间接触力强力链容易形成。
In order to study the strength-size effect of direct shear test of non-cohesive coarse grained soil, the direct shear tests of different maximal particle size non-cohesive coarse grained soil were carried out with the same specimen size straight shear tester. The maximum particle size of the test soil was 40, 20, 10, 5 and 2 mm respectively. The soil samples of each group had self-similar mass fractal structure to ensure the same pore characteristics of the soil. The method of pre-implantation of vertical tin wire Cut width. The results show that with the increase of the maximum particle size, the shear band width and strength increase, and when the maximum particle size is greater than 1/20 of the sample height, obvious strength size effect occurs; the bite force c and the internal friction angle φ With the ratio of the sample height to the maximum particle size decreases, and with the logarithm showed a significant linear relationship; with the maximum particle size increases, the size effect of the strength gradually obvious because the number of particles in the shear zone decreases, the particles Indirect force chain easy to form.