黄土湿陷性与其物理力学指标的关系及评价方法

根据黄土物理力学指标可快速评价其湿陷性,故很有必要对黄土湿陷性与其物理力学指标之间的关系进行研究。为探究该关系,在大量现场试坑浸水试验及相应的室内试验基础上,采用数理统计、理论分析和数据挖掘相结合的方法,针对郑西(郑州—西安)高速铁路沿线的Q₃大厚度湿陷性黄土,系统研究了马兰黄土湿陷系数与深度、含水率、干密度、孔隙比、塑性指数和压缩系数之间的关系,并提出工程中用单个或多个物理指标评价黄土湿陷性的新方法。研究结果表明黄土湿陷系数与其物理力学指标之间具有较好的相关性,其中湿陷系数与深度、含水率、干密度之间呈线性负相关性,与孔隙比呈线性正相关性;对于关中地区Q₃黄土,黄土是否具有湿陷性的界限含水率为20%,界限干密度为1.4 g/cm³,界限孔隙比为0.9;相比而言,孔隙比对黄土湿陷系数影响最大,干密度和含水量次之,而后是塑性指数,压缩系数与湿陷系数的相关性较低。最后,基于数据挖掘技术,提出用多个物理指标综合评价黄土湿陷性的经验公式,可用于估算黄土的湿陷性。

Relationship between Collapsibility and Physical-mechanical Indexes of Loess and Evaluation Methods

The collapsibility of loess can be evaluated rapidly through physical and mechanical indexes.On the basis of field immersion tests and corresponding indoor tests,we analyze the relationship of loess collapsibility against depth,water content,dry density,void ratio,plasticity index,and compressibility coefficient using mathematical statistics,theoretical analysis,and data mining.The thick Q3 loess along the Zhengzhou-Xi'an Highway is taken as research background.The research conclusions are as follows:the coefficient of loess collapsibility is well correlated with physical and mechanical indexes,among which depth,moisture content,and dry density are linearly negative-ly correlated with collapsibility;void ratio is linearly positively correlated with collapsibility.The limit moisture con-tent for loess collapse is 20％,limit dry density,1 .4 g/cm3,and limit void ratio,0.9.In comparison,the collaps-ibility coefficient is mostly influenced by void ratio,followed by dry density,moisture content,plasticity index and coefficient of compressibility.In addition,we put forward an empirical formula of evaluating loess collapsibility by using multiple physical indexes based on data mining.