Collaborative Research: Experimental and Computational Investigation of Multiphase Consolidation for Partially Saturated Soils

部分饱和土是三相土材料，在固体颗粒之间的空隙中含有空气和水。 此类土壤在土木工程的现场施工中经常遇到，包括地基、垃圾填埋场、斜坡、挡土墙、压实填料和公路。 部分饱和土的力学行为还没有得到很好的理解，因为复杂的相互作用的三相。 该奖项支持基础研究，使用实验和计算机建模方法，提供部分饱和土壤变形和体积变化（即，在不同的荷载条件下。 这项工作有可能改变目前对部分饱和土的理解，这与取样，测试，表征和监测有关，以及使用这些材料设计和建造可持续的民用基础设施。这项研究计划的目标是对部分饱和土的多相固结进行全面的实验和计算研究，然后评估这些发现在岩土工程和地质环境工程中的相关应用的意义。 这项工作既有内在的科学价值，在推进目前的广泛的物理过程的理解，以及实际效用方面的发展改进的预测方法，沉降，流体流动，有效应力，最终材料的性能配置文件的广泛的工程应用。 实验计划将包括多相固结试验进行了各种土壤与不断变化的应力和水文条件。 将使用基于统一有效应力理论和吸力特征曲线的新的一致框架来解释测量数据。 计算程序将开发新的模型，使用一种新的三拉格朗日（固体-水-空气）离散化方法来跟踪每个相的运动，同时考虑几何和材料非线性，可压缩非达西气体流动，耦合流效应，相不连续性，以及机械和水文滞后。 一旦得到验证，新模型将用于进行数值模拟研究，以评估多相土壤固结对各种工程应用的重要性，并强调这些影响对更广泛的岩土工程和地质环境工程界的重要性。

Partially saturated soils are three-phase earth materials that contain both air and water in the void space between the solid grains. Such soils are commonly encountered in field construction for a wide range of civil engineering works, including foundations, landfills, slopes, retaining walls, compacted fills, and highways. The mechanical behavior of partially saturated soils is not well understood because of complex interactions of the three phases. This award supports fundamental research, using both experimental and computer modeling methods, to provide needed knowledge of the mechanisms by which partially saturated soils undergo deformation and volume change (i.e., consolidation) under various loading conditions. This work has the potential to transform current understanding of partially saturated soils, which has relevance to sampling, testing, characterization, and monitoring, as well as design and construction of sustainable civil infrastructures using these materials.The objective of this research program is to conduct a comprehensive experimental and computational investigation of multiphase consolidation for partially saturated soils, and then assess the significance of these findings for relevant applications in geotechnical and geoenvironmental engineering. This work has both intrinsic scientific merit in terms of advancing the current understanding of a widespread physical process, as well as practical utility in terms of developing improved prediction methods for settlement, fluid flow, effective stress, and final material property profiles for a wide range of engineering applications. The experimental program will include multiphase consolidation tests conducted for a variety of soils with changing stress and hydrologic conditions. Measured data will be interpreted using a new and consistent framework based on unified effective stress theory and the suction stress characteristic curve. The computational program will develop new models using a novel tri-lagrangian (solid-water-air) discretization method to track movements of each phase while accounting for geometric and material nonlinearities, compressible non-Darcy gas flow, coupled flow effects, phase discontinuities, and mechanical and hydrologic hysteresis. Once validated, the new models will be used to perform numerical simulation studies to assess the significance of multiphase soil consolidation for a variety of engineering applications and highlight the importance of these effects to the broader geotechnical and geoenvironmental engineering community.