颗粒形状对砂性土宏细观力学性质的影响

针对多数关于颗粒形状对砂性土宏细观力学性质的影响方面的研究中忽略的两个问题,天然砂性土中颗粒的随机不规则形状和对比试验中颗粒的体积不相等问题,基于已有的研究成果,对天然的硅质粗砂做了直剪试验,然后通过离散元程序PFC对其进行模拟,并设计了基于圆形颗粒的对比试验。试验结果表明,颗粒形状只有在较高的法向应力下才可以增加砂性土的剪切峰值强度,当法向应力较低时,不规则形状颗粒组成的砂性土的剪切峰值强度还不如圆形颗粒组成的砂性土,且当颗粒间的摩擦作用较弱时会有类似的现象,临界值强度并没有因颗粒形状的不规则而有明显差别。对此结果的细观机理也做了浅析,认为在较低法向应力时,圆形砂性土较大的剪胀角是其剪切峰值强度较大的主要原因。

Influence of particle shape on the macro- and micro-mechanical properties of sandy soil

In view of the two problems that are ignored in most studies on the influence of particle shape on the macro- and meso-mechanical properties of sandy soils, the random irregular shape of particles in natural sandy soil and the unequal volume of particles in comparative experiments. Based on the existing research results, a direct shear test was done on natural siliceous coarse sand, and then the discrete element program PFC was used to simulate it, and a comparative test based on round particles was designed. The test results show that the particle shape can increase the peak shear strength of sandy soil only under higher normal stress. When the normal stress is lower, the peak shear strength of sandy soil composed of irregularly shaped particles is still lower. It is not as good as sandy soil composed of round particles, and when the friction between the particles is weak, there will be a similar phenomenon. The critical value strength is not significantly different due to the irregular shape of the particles. The meso-mechanism of this result has also been analyzed, and it is believed that the larger dilatancy angle of round sandy soil is the main reason for the larger shear peak strength when the normal stress is lower.