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黄土的湿陷性是其重要的工程特性,常用一维压缩应力条件下的湿陷系数、自重湿陷系数和湿陷起始压力等指标定量评价。影响黄土湿陷性的因素较多,包括土的粒度、密度、湿度等基本物理性质指标,且各因素之间并非完全独立,存在一定相关性。采用因子分析法,通过对西安地铁4号线黄土高台地和宝鸡—兰州高速铁路隧道黄土塬湿陷性黄土场地地层物性质指标的统计分析和相关性分析,首先确定了相对独立的含水比(含水率与液限之比)和孔隙比3个物性指标反映的两个因子。然后,依据湿陷性黄土场地的试验资料,通过多元线性回归分析,分别得到了两个场地黄土的自重湿陷系数、湿陷起始压力以及压缩模量与含水比和孔隙比之间的相关关系。最后,比较分析了两个场地黄土自重湿陷系数、湿陷起始压力和压缩模量计算值与实测值,验证了利用因子分析法寻找影响黄土湿陷性的独立因子,建立黄土湿陷性参数与独立影响因子之间相关关系的合理性和准确性。针对两个地区两类地貌单元湿陷性黄土场地,建立的黄土湿陷性参数的相关关系具有快速、准确的评价黄土湿陷性和黄土地基湿陷变形的实际意义。
Collapsibility of loess is an important engineering characteristic. It is often quantitatively evaluated by such indexes as collapsibility coefficient under one-dimensional compressive stress, weight collapse coefficient and initial collapse pressure. There are many factors that affect the collapsibility of loess, including the indexes of basic physical properties such as grain size, density and humidity of soil, and the factors are not completely independent between each other. There is a certain correlation between them. By means of statistical analysis and correlation analysis of the stratigraphic properties of Loess Plateau in Xi’an Subway Line 4 and collapsible loess in Loess Plateau of Baoji-Lanzhou High Speed Railway, the relative independent water content ratio Moisture content and liquid limit ratio) and porosity than the three physical indicators reflect the two factors. Then, based on the experimental data of collapsible loess site, the multiple linear regression analysis was used to get the correlations between the self-weight collapsibility coefficient, initial collapse pressure, compressive modulus, water cut ratio and void ratio of two loess sites relationship. Finally, comparative analysis was made of the collapsible weight of collapsible loess, the calculated initial compressive modulus and compressive modulus of collapsed loess, and the calculated values and measured values of the compressive modulus of collapsed loess were compared. The factor analysis was used to find out the independent factors affecting the collapsibility of loess, The rationality and accuracy of the correlation between parameters and independent influencing factors. The correlation between the collapsible loess parameters and the two collapsible loess sites in the two regions shows that the loess collapsibility and the collapsible deformation of the loess foundation can be quickly and accurately evaluated.