蒸发作用下黏性土水分迁移规律及工程性质响应研究

Evaporation is one of the most direct interaction modes between drought climate and natural soils. It can significantly alter soil moisture content and engineering properties, and is also the primary cause of many engineering and environmental geology problems. Considering the increasing frequency of drought climate and the related disasters, in this project, clayey soil is selected as the typical test material due to its sensitivity to drought climate. In order to understand the moisture transport characteristics and engineering property response of clayey soil as subjected to evaporation, both the laboratorial model test and in-situ long term monitor test will be performed with combination of electrical resistivity tomography (ERT) technique and micro scale analysis. The following subjects will be systematically investigated: the 3D distribution and transport characteristics of soil moisture during evaporation; the coupled interactions between moisture transport and soil multiple fields (suction, deformation, etc.); atmosphere-clayey soil long term interaction characteristics; the desorption process of absorbed water on clay mineral surface and the water-soil micro-interaction mechanisms; response of physical and mechanical properties of clayey soil during evaporation. Based on the obtained test results, and with the combination of theoretical knowledge derived from soil science, soil structure and soil mechanics, the mass and energy exchange behavior between atmosphere and soil and the related drought disaster mechanisms will be revealed. A theoretical atmosphere-soil interaction model will be proposed by considering both the atmospheric and soil factors. The achievements of this project are of great significant not only for directing drought resisting and disaster reduction in engineering geology field, but also for protecting geological environment.

蒸发是干旱气候-土体相互作用的主要方式，是导致土体水分场和工程性质发生改变的重要前提，也是许多工程地质和环境地质问题的重要诱因。本项目以干旱气候灾害为研究背景，选取对干旱气候比较敏感的黏性土为研究对象，分别开展室内模型试验和原位长期监测试验，同时结合高密度电阻率成像技术及微观分析手段，围绕蒸发作用下黏性土水分迁移规律及工程性质响应这一中心课题，着重对以下内容开展系统研究：蒸发作用下黏性土水分场的三维空间分布及迁移特征、水分迁移过程与土体剖面多场（吸力、变形等）之间的耦合作用、大气-黏性土长期相互作用特征、黏土矿物吸附结合水的解吸过程及水-土微观作用机制、黏性土物理力学性质响应。在试验研究的基础上，结合多学科理论，进一步阐明干旱气候-黏性土物质能量交换规律及灾变过程，并构建同时考虑气象和土性因素的大气-土体相互作用理论模型，以期使本项目研究成果为工程地质抗旱减灾和保护地质环境提供指导。

蒸发是地表水循环的一个重要环节，是大气-地表物质能量交换的主要方式，也是导致土体水分场变化和工程性质灾变的重要前提。在此背景下，本项目选取对干旱气候比较敏感的黏性土为研究对象，分别开展室内模型试验和原位长期监测试验，围绕蒸发作用下黏性土水分迁移规律及工程性质响应这一中心课题，着重对蒸发作用下黏性土水分场的三维空间分布及迁移特征、水分迁移过程与土体剖面多场参数之间的耦合作用、大气-黏性土长期相互作用特征、黏土矿物吸附结合水的解吸过程及水-土微观作用机制、黏性土物理力学性质响应等开展了大量研究工作，取得了系列创新性成果，主要体现在：.（1）突破了以往蒸发试验研究中土体含水率点式监测的局限性，建立了一套基于高密度电阻率成像技术（ERT）的土体蒸发过程中内部水分场分布、迁移规律、裂隙发育的三维定量分析与精细化监测方法；.（2）突破了以往土体蒸发研究只注重气象因素单向作用及蒸发量计算的局限性，揭示了土性因素对蒸发的反作用及蒸发作用下土体的工程性质响应特征；.（3）阐明了干旱气候作用下土体水分蒸发和迁移过程与水分场、吸力场、变形场之间的耦合作用机理及大气-土体物质能量交换规律，建立了同时考虑气象和土性因素的大气-土体相互作用理论模型；.（4）研发了可实时探测蒸发过程中土体内部水/力学性质时空演化特征的超微型贯入仪，构建了贯入阻力与土体剖面含水率及吸力之间的定量关系；.（5）定量获得了亲水性黏土矿物不同吸附结合水类型对应的比重及界限参数，掌握了蒸发过程中亲水性黏土矿物的微观脱水机制及其与宏观体变行为之间的关联，阐明了不同结合水类型的脱水能量学特征对黏性土水分蒸发和迁移过程的影响机理。.上述成果对掌握干旱气候-黏性土物质能量交换规律，分析干旱气候作用下黏性土灾变过程，指导干旱地区的工程实践和防灾减灾具有重要意义。累计发表论文50余篇，其中SCI论文15篇，申请发明专利2项，培养研究生14名。