细颗粒组分含量对钙质砂抗剪强度的影响

由于吹填过程的水力分选作用钙质砂土地基颗粒分布不均匀，容易形成分布不均、形态各异的以不同细粒含量的粉细砂层为主的细粒汇集层，引起钙质砂土地基承载力和不均匀沉降问题。开展不同细粒含量的粉细砂三轴固结排水剪切试验，分析细粒含量对钙质砂土力学特性的影响。研究结果表明，（1）当细粒含量增加时相同围压下土样剪胀性逐渐减弱，且峰值偏应力也逐渐减小；（2）各组试样干密度为1.40 g/cm3状态下各含量粉细砂均表现出应变软化特征，当细粒含量为10%时粉细砂土体强度稳定性最差，之后稳定性随细粒含量增加而逐渐增大；（3）钙质细砂由于颗粒咬合作用，具有表观黏聚力，当细粒含量小于40%时，随着细粒含量增加，颗粒之间的咬合作用显著降低，表观黏聚力线性减小。研究成果可为粉细砂层的地基处理及边坡稳定分析提供参考。

Effect of fine particles content on shear strength of calcareous sand

The hydraulic sorting effect in the dredger filling process results in uneven distribution of grains with different sizes in the calcareous sand foundation. Because of the formation of fine-grained layer, composed of silt and fine-grained sands with different contents of fine-grained particles, which is uneven distributed and very heterogeneous, it may lead to the bearing capacity and uneven settlement problems of the calcareous sand foundation. In this paper, to study the effect of fine-grained particles content on mechanical properties of calcareous sands, a series of triaxial shear tests under consolidation drainage conditions are carried out on fine sands with different contents of silty-sands. The results show that (1) the dilatancy property and peak deviator stress of soil samples decrease gradually when the content of fine particles increases under the same confining pressure. (2) All these fine sands with a dry density of 1.40 g/cm3, show the strain softening characteristics. The worst stability occurs in samples with 10% content of silty-sands, and it strengthens with the increased content of silty-sands. (3) The particle occlusion effect, makes a non-negligible apparent cohesion in the calcareous fine-grained sands. However, a significant decline in the cohesion occurs due to the decreased particle occlusion effect with the increase in silty-sand content when the fine particles content is less than 40%. Results in this paper can provide references for foundation treatment and slope stability analysis of fine-grained sand layers.