干密度和含水量对重塑黄土抗剪强度特性的影响研究

Influence of dry density and water content on shear strength characteristics of remolded loess

为阐明生产建设项目回填土边坡抗剪强度与土壤含水量和干密度的关系,以陕西省西安市周至县活龙山研究区土壤(典型黄土)为研究对象,根据实地调查取样,采用击实法制备3个密度梯度、7个含水量梯度的21组供试土样,进行直剪试验,分析土壤干密度与含水量对重塑土抗剪强度指标的影响。结果表明:在密度相同的条件下,重塑土的内摩擦角随着含水量的增加整体呈现下降趋势,当含水量过大时出现小幅跃升现象;土壤内摩擦角随干密度的变化规律不显著。土样粘聚力与干密度呈正相关,与含水量呈负相关,且含水量较低或密度较大时,粘聚力的变化幅度较大。土壤抗剪强度与干密度均呈线性正相关,与含水量呈负相关。说明干密度和含水量对重塑土抗剪强度特性有较大影响;干密度主要通过粘聚力影响抗剪强度,而含水量则通过粘聚力和内摩擦角共同影响抗剪强度。

In order to clarify the relationships between production and construction project backfill slope shear strength with soil water content and dry density,we chose the Longshan soil （typical loess） of Zhouzhi County of Xi＇an in Shaanxi as the research object.According to the field investigation,the compactions were prepared with 3 density gradients and 7 water gradients,a total of 21 combinations for direct shear test.The effects of density and moisture content on the shear strength index of remolded loess dry soil were investigated.The experimental results show that：in the condition of the same density, the internal friction angle of remolded soil presents a downward trend with the increase of water content, and a small jump phenomenon occurs when the water content is too large;the soil internal friction angle with the variation of dry density is not significant. The cohesive strength of soil sample is positively correlated with the dry density,and it has a negative correlation with water content, and the cohesive strength varies greatly when the water content is low or the density is large.The soil shear strength has a linear positive correlation with dry density,and negatively correlated with water content.The test shows that dry density and water content have a great influence on the shear strength characteristics of remolded loess. Dry density mainly influences the shear strength through cohesion,while water content affects the shear strength by cohesive strength and internal friction angle.