Collaborative Research: SWCC Based Models for Realistic Simulation of Swell Behavior of Expansive Soils

目前确定非饱和膨胀土体积变化特性的工程实践大多是基于简化的试验，并与指标特性相关联。这种做法可能会导致不经济和容易损坏的基础设计。因此，有一个基础性的研究需要回顾当前膨胀土中的表征实践，并对其进行修订，以反映非饱和土力学知识的现状。来自德克萨斯大学阿灵顿分校和亚利桑那州立大学的研究团队正在努力通过执行各种实验和建模任务来满足这一研究需求。试验任务包括对八种类型的膨胀土进行调查，以确定在广泛的土壤吸力范围内的土壤水分特征曲线，并考虑粘土矿物学、含水率、干重和应力历史来测量体积膨胀应变和膨胀压力。建模任务包括开发使用SWCC属性、粘土矿物学、孔洞数据来预测膨胀特性的分析公式，以及研究基于流动和变形的有限元建模以模拟体积变化行为。这项研究的最终成果是开发了利用非饱和土力学原理更好地预测膨胀土性质的方法。该研究的更广泛影响将集中在培训研究生和本科生非饱和土力学和膨胀土特性；将研究成果纳入本科和研究生课程；加强对膨胀土体积变化行为的了解，为膨胀土基础设施的设计提供更好的表征工具；让女性和少数族裔学生参与研究任务；以及在暑期课程中向K-12学生教授简单的实验模块，以提高他们对土木工程的兴趣。

Current engineering practice for determining the volume change behavior of unsaturated expansive soils are mostly based on simplified tests, and correlations with index properties. Such practices can lead to uneconomical and distress prone foundation designs. Hence, there is a fundamental research need to review the current characterization practices in expansive soils and to revise them to reflect the current state of knowledge of unsaturated soil mechanics. The research team from both UT Arlington and Arizona State University are working towards accomplishing this research need by performing various experimental and modeling tasks. Experimental tasks include investigations on eight types of expansive subsoils to determine Soil Water Characteristic Curves (SWCCs) over a wide range of soil suction, measure volumetric swell strain and swell pressure with consideration of clay mineralogy, moisture content, dry unit weight, and stress history. Modeling tasks include development of analytical formulations to predict swell characteristics using SWCC attributes, clay mineralogy, pore void data, and study flow and deformation based finite element modeling to simulate volume change behavior. The final outcome of this research is the development of methods for better predictions of expansive soil properties using unsaturated soil mechanics principles.The broader impacts of the research will focus on training graduate and undergraduate students in unsaturated soil mechanics and expansive soil characterization; incorporating research findings into undergraduate and graduate courses; strengthening understanding of volume change behavior of expansive soils and providing better characterization tools for design of infrastructure foundations on expansive soils; involving women and minority students in research tasks; and teaching simple experimental modules in summer classes to K-12 students to enhance their interests in civil engineering.