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基于三峡水库崩坡堆积物岸坡变形破坏问题,采用三维离散元软件PFC3D,建立了崩坡堆积层土石混合体大型三轴剪切试验模型,并对含石量分别为0%,20%,40%,60%,80%和100%以及截面尺寸分别为60cm×30cm,65cm×32.5cm,70cm×35cm,75cm×37.5cm和80cm×40cm的试样进行剪切破坏模拟。结果表明:土石混合体粘聚力随着含石量的增加而减小,近似呈线性关系。内摩擦角在含石量小于40%时,几乎不变;当含石量大于40%且小于60%时,内摩擦角处于过渡阶段,开始增大,且增大程度越来越快;当含石量大于60%时,内摩擦角急剧增加。同一含石量试样的粘聚力随着试样尺寸的增大而逐渐减小,且减小程度在含石量40%左右达到最大。随着试样尺寸的增大,含石量为0%的试样内摩擦角几乎不变;20%,40%和60%含石量的试样内摩擦角减小;80%,100%含石量的试样内摩擦角增大。崩坡堆积物试样破坏在“低含高围”情况下时出现“剪涨”现象,在“高含低围”情况下出现“剪缩”现象。研究认为PFC3D程序可以较好地研究水库崩坡堆积层的力学特性。
Based on the three-dimensional discrete element software PFC3D, a large-scale triaxial shear test model of soil-rock mixture with collapsed slope was established based on the problem of bank slope collapse and deformation in the Three Gorges Reservoir. 40%, 60%, 80% and 100%, and specimens with cross-sectional dimensions of 60 cm × 30 cm, 65 cm × 32.5 cm, 70 cm × 35 cm, 75 cm × 37.5 cm and 80 cm × 40 cm, respectively. The results show that the cohesion of soil-rock mixture decreases with the increase of rock mass content, and has a linear relationship. The internal friction angle is almost unchanged when the content of rock is less than 40%; when the content of rock is more than 40% and less than 60%, the internal friction angle is in the transitional phase and starts to increase and increases more and more rapidly; When the stone content is more than 60%, the internal friction angle increases sharply. The cohesion of the same stone-containing sample decreases with the increase of the sample size, and the degree of decrease reaches the maximum at about 40% of the stone content. With the increase of the sample size, the internal friction angle of the sample containing 0% stone is almost unchanged; the internal friction angle of the sample with 20%, 40% and 60% The internal friction angle of the stone containing sample increases. The collapse of slope debris accumulation sample “” shear rise “phenomenon in the case of ” low height with high “,” " The study shows that the PFC3D program can well study the mechanics characteristics of reservoir collapse landslide.