斥水剂作用下非饱和土水特性变化规律及宏细观机理研究

The hydrophobic soils will be obtained by different hydrophobic powders. The methods of WDPT (Water Drop Penetration Time) and MED (Molarity of an Ethanol Droplet) will be used to determine the soil water repellency. The effects of aqueous solutions with different solutes on soil water repellency will be obtained and the evaluation criterion of soil water repellency will be improved. The surface morphology of soil particles under modifying will be observed by ESEM and the change rule will be obtained. The contact angle of soil under modifying will be measured by contact angle apparatus. Then a new classification and evaluation system of soil water repellency will be established considered the macro-meso scopic. The tests of water-holding capacity of hydrophobic soils will be carried out to obtain the SWCC by high speed centrifuge. A series of water infiltration experiments will be carried out by modified triaxial apparatus and soil column instruments in order to obtain the change rule of soil hydraulic parameters, and the model of moisture movement model of hydrophobic soils will be established. A series of tests of hydrophobic soils in deformation characteristics and mechanical behavior will be carried out by unsaturated apparatus, and the model of mechanical behavior of hydrophobic soils will be established. Based on the experimental results and theoretical analysis, the preparing methods of hydrophobic soils which could meet the orders of impermeability, strength and deformation meanwhile will be presented. Then the hydrophobic soils will be applied in practical engineering finally. It can provide the research basis for the hydrophobic soils widely appling in the civil and hydraulic engineering.

采用斥水剂对非饱和土进行处理，获得不同斥水度的土体。采用滴水渗透时间法和酒精溶液入渗法开展土体斥水度测定试验，获得含不同溶质水溶液对土体斥水度的影响规律，完善现有土体斥水度评价标准；采用环境扫描电镜开展改性前后土体颗粒表面形态观测试验，获得相应的变化规律；采用接触角测试仪开展土体改性前后接触角测定试验，进而建立宏细观相结合的斥水土分类与评价体系；采用高速离心机，开展斥水土的持水性能试验，获得相应的土水特征曲线；采用改进三轴仪，开展不同条件下斥水土的水分运移试验，获得相应的水分运移特征和变化规律，建立斥水土的水分运移模型；采用相关测试仪器，开展斥水土的变形特性与力学行为试验，建立斥水土的力学行为模型。在此基础上，提出同时满足防渗、强度和变形的斥水土的制备工艺和工程实施方案，结合实际工程开展斥水土的初步应用。解决上述问题可为斥水土应用于土木水利工程领域提供研究基础。

1.项目背景.采用斥水剂对土壤进行斥水化处理，以提升土壤自身抗渗性能，进而达到工程防渗目的，是本项目研究思路，对其深入开展研究十分必要。.2.主要研究内容.（1）开展了斥水剂作用下土壤抗剪强度测定及其变化规律试验。.（2）开展了改性土壤的斥水性与入渗性能试验。.（3）归纳总结了斥水土壤性质及工程应用研究进展。.（4）开展了斥水剂作用下土壤物理性质变化规律试验。.（5）开展了斥水土壤斥水度变化规律及影响因素试验。.（6）开展了十八胺改性下膨胀土斥水与变形特性试验。.（7）开展了十八胺改性下膨胀土的抗剪强度试验。.（8）开展了斥水土覆盖亲水土下植被生长试验。.（9）开展了斥水土覆盖土质边坡的室内模型试验。.（10）开展了不同溶质作用下斥水土抗剪强度变化规律试验。.3.重要结果及关键数据.（1）不同二氯二甲基硅烷含量下的5种改性砂土斥水等级均为极度。随着DMDCS含量的增加，改性砂土的斥水等级不断增大，而黏聚力和内摩擦角均逐渐减小。.（2）十八烷基伯胺（OCT）含量越高，土壤斥水等级越大，上限含水率越低，而下限含水率越高。土壤斥水性越强，稳定入渗率呈下降趋势。起始出渗时间随水头差的增大而减小，随土壤斥水性的增大而增大。.（3）随着斥水土壤初始含水率的增加，土壤斥水等级呈现先增后减态势。斥水土壤塑限、最大干密度及最优含水率随着OCT含量的增大而增大，而液限则减小。当温度由0℃升至105℃时，土壤斥水程度为先增后减。强酸会显著降低OCT土壤的斥水性，洁厕剂、洗洁精等在一定程度上能降低土壤斥水性，而乙醇和丙酮的影响不大。.（4）随着含水率和OCT含量的增加，改性膨胀土的膨胀率逐渐降低。抗剪强度与十八胺含量呈线性关系，符合摩尔库伦抗剪强度准则。.（5）斥水土覆盖边坡下，百喜草生长良好，是斥水土生态护坡技术的优选植被。提出了“斥水土+植被”生态护坡技术实施方法。.（6）不同溶液浓度对OCT斥水土壤抗剪强度的影响程度表现为：硫酸铜 > 草酸 > 水溶性氮酮 > 脂肪醇聚氧乙烯醚 > 椰子油脂肪酸二乙醇酰胺 > 大苏打。.4.科学意义.通过四年来的研究工作，我们进一步认识了斥水土壤基本性质，具有较好的理论价值和工程意义，为今后深入研究和解决工程防渗问题提供参考。