静水条件下冰冻泥沙水下休止角的试验研究

Experimental study on the underwater angle of repose of frozen sediment in static water conditions

为研究冰冻泥沙在静水中融化后休止角的变化规律以及不同环境中泥沙休止角的差异,采用粒径为0～1 mm、1～2 mm、2～4 mm的泥沙试样,进行了风干泥沙在空气中的休止角、无冰泥沙以及冰冻泥沙水下休止角试验。试验结果表明:对于同一粒径范围的泥沙,风干沙在空气中的休止角最大,冰冻泥沙水下休止角次之,无冰泥沙水下休止角最小,三种试验情景中休止角均随泥沙粒径的增大而增大;泥沙水下休止角与风干沙在空气中休止角的差异,主要与水对泥沙的润滑作用以及泥沙在不同介质中的有效容重系数有关;泥沙在水下受到冰的影响表现为局部泥沙颗粒滑动,这更有利于斜坡上泥沙的堆积,相对于无冰泥沙而言,冰的存在使泥沙水下休止角增大。

Dry sediment,underwater sediment and underwater-frozen sediment are used to investigate the law of the angle of repose in different conditions. In this experiment,the particle size ranges of sediment are 0 ~ 1 mm,1 ~ 2 mm,2 ~ 4 mm,respectively. The results show that: 1) For the sediment with the same particle size,the angle of repose of dry sediment is the maximum,followed by the underwater-frozen sediment,and then by the ice-free sediment. 2) The sediment repose angle increases with particle size; the difference between the angles of repose of dry sediment and underwater sediment are mainly dependent on the effective bulk density coefficient of the sediment in various mediums. 3) A local sliding phenomenon exists during the formation of underwater angle of repose,resulted from the ice. It is conducive to the accumulation of sediment on the slope. Compared with the ice-free sediment,the ice between the sediment particles leads to increase of angle of repose.