基于数据挖掘的土?水特征曲线演化规律研究

土?水特征曲线是非饱和土持水性能和水气运移规律的重要表征，由于其测试过程繁杂、影响因素众多，很难通过系列试验和数学模型全面表达。为探索土的类型和物理状态对土?水特征曲线的影响，以国内外大量试验数据为基础，以反映其形态的3个特征值（进气值、减湿率、残余含水率）为对象，采用数据分析统计方法揭示不同赋存条件对特征值的作用规律，采用机器学习方法探究影响因素的敏感性。研究结果表明：土体的物质组成（颗粒级配、粒径尺度、塑性指数）及赋存状态（密实程度、饱和含水率、干湿循环作用、环境温度）是影响其持水性能的常见分析指标，各影响因素对3个特征值的影响特征既有巨大差异也有相互联系，敏感性成果表明代表黏粒含量的塑性指数和反映密实程度的干密度是影响土体持水性能的最主导因素，给出的特征值分布范围考虑了两个主导因素的影响，具有较强的代表性和借鉴意义。

Evolution law of the soil-water characteristic curve based on data mining method

The soil-water characteristic curve (SWCC) is an important characterization of the water-holding performance and water-vapor transport law of unsaturated soil. Due to its complicated testing process and many influencing factors, it is difficult to fully express it through a series of tests and mathematical models. The aim of this study is to explore the influences of soil type and physical state on SWCC. The abundant test data from worldwide research are collected as the database, and three characteristic values of SWCC (air-entry value, dehumidification rate and residual volumetric water content) are selected as the analytic target. Then, some data analyses are adopted to reveal the influence and sensitivity of different occurrence conditions on the characteristic values, and machine learning methods are employed to analyze the sensitivity. In the database，the material composition (particle gradation, particle size, plasticity index) and occurrence state (compactness, saturated water content, dry-wet cycle and ambient temperature) of the soil are common indicators that affect its water holding capacity. The influence mechanism of above factors presents some great differences but also obvious interrelation. The results of sensitivity analysis indicates that the plasticity index that reflects the clay content and the dry density that represents compactness) are two dominant factors influencing the water retention capacity of unsaturated soils. The distribution ranges of three characteristic values are also provided with considering the influences of two dominant factors, and can present most of test results and guide the engineering application.