干密度对非饱和粉质黏土土水特征的影响

Effect of Dry Density on Soil-Water Characteristics of Unsaturated Silty Clay

摘要: 非饱和土广泛地存在于自然界和工程领域，其工程性质和行为特征备受关注，对工程建设安全性和地质环境稳定性至关重要。土–水特征曲线(SWCC)作为描述非饱和土的基本工具，揭示了土壤湿度状态与基质吸力的变化关系，其形状和参数与土壤力学行为、渗透性及工程应用紧密相关，而干密度的变化则直接影响土体的孔隙结构、持水性能和力学响应。基于此，本研究基于压力板仪，开展土–水特征曲线测试，探究了不同干密度条件下粉质黏土土–水特征曲线的变化规律。结果表明：土样的干密度对土–水特征曲线的变化具有显著影响，相同基质吸力下，初始干密度越大的试件对应的质量含水率越小，随着干密度的增大，试件之间质量含水率的差异逐渐减小；当基质吸力由0增大至500 kPa时，干密度为1.5、1.6、1.7 g/cm3的试件的质量含水率分别减小了11.1%、10.7%、9.8%；基于VG模型，建立考虑干密度的土–水特征曲线模型，可快速预测山东某地区粉质黏土土–水特征曲线，提供便捷途径。

Abstract: Unsaturated soil widely exists in nature and engineering fields. Its engineering properties and be- havior characteristics have attracted much attention, which is very important for the safety of engineering construction and the stability of the geological environment. The soil-water characteristic curve (SWCC), as a basic tool to describe unsaturated soil, reveals the relationship between soil moisture state and matric suction. Its shape and parameters are closely related to soil mechanical behavior, permeability, and engineering application. The change of dry density directly affects the pore structure, water holding capacity and mechanical response of soil. Based on this, this study carried out the soil-water characteristic curve test based on the pressure plate instrument and explored the variation law of the soil-water characteristic curve of silty clay under different dry density conditions. The results show that the dry density of the soil sample has a significant effect on the change of the soil-water characteristic curve. Under the same matrix suction, the larger the initial dry density, the smaller the corresponding mass moisture content of the specimen. With the increase of dry density, the difference of mass moisture content between specimens gradually decreases. When the matric suction increased from 0 to 500 kPa, the mass water content of the specimens with dry density of 1.5, 1.6 and 1.7 g/cm³ decreased by 11.1 %, 10.7 % and 9.8 %, respectively. Based on the VG model, a soil-water characteristic curve model considering dry density is established, which can quickly predict the soil-water characteristic curve of silty clay in a certain area of Shandong and provide a convenient way.