粗颗粒盐渍土大型剪切强度试验研究

Experiments on Large-scale Direct Shear Strength of Coarse-grained Saline Soil

对新疆准东地区的粗颗粒盐渍土进行了室内大型剪切实验,研究了粗颗粒盐渍土的剪切破裂面形态、剪应力-位移曲线特征及干密度对抗剪强度指标的影响规律。结果表明:粗颗粒盐渍土剪切破裂面具有明显的高低不平与上下起伏的形态,剪切过程中土颗粒间表现出明显的镶嵌咬合和剪胀特征,使粗颗粒盐渍土表现出一定的黏聚力;粗颗粒盐渍土剪切应力随剪切位移变化的承载过程表现为应变软化类型,具有明显的峰值强度。随着干密度(压实系数)增加,抗剪强度指标显著增加,亦即提高粗颗粒盐渍土压实系数可显著提高地基承载力,具有明显的工程效益。

Large-scale shear test on coarse-grained saline soil in Zhundong area of Xinjiang was carried out to analyze the shear fracture surface mode,characteristics of shear stress-displacement curve,and influence of dry density on shear strength index. The results show that coarse-grained saline soil has uneven shear fracture surface resulting in the obvious characteristics of mosaic and occlusion between soil particles,and the dilation effect. Therefore the coarse-grained saline soil has obvious cohesive strength and the shear stress-displacement curve has obvious peak intensity which can be characterized by strain softening type. With the increase of dry density（ compaction coefficient） the shear strength index increases significantly. Therefore,increasing the compaction factor can greatly improve the bearing capacity of foundation and obtain the favorable engineering benefit.