Unsaturated soil mechanics & near-ground-surface phenomena

非饱和土力学

• 批准号: 3787-2008
• 负责人: Fredlund, Delwyn
• 金额: $ 4.37万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=388843
• 关键词: Unsaturated; soil; mechanics; near; ground

There were two primary subjects that have been historically been by-passed in textbooks on classical soil mechanics; namely, the behavior of unsaturated soils and the quantification of moisture flux conditions at ground surface. The last 40 years have witnessed rapid strides in our understanding of unsaturated soil mechanics as it applies to relatively homogeneous continua. There are; however, two aspects of unsaturated soil mechanics that stand in great need of further research. The first aspect involves the structural characterization of the soil conditions near ground surface. Often these soils contain extensive fissures, fractures and cracks that significantly affect the unsaturated soil properties. It is proposed that the secondary macrostructure of these soils be characterized through use of bimodal mathematical functions. It is proposed that there be one air entry value associated with the macrostructures features and another air entry value associated with the intact matrix of the soil. The unsaturated soils near to the ground surface thus become bimodal, nonlinear and hysteretic. Many of these soils also exhibit significant volume change during wetting and drying. The second aspect of unsaturated soil mechanics in need of research is the quantification of moisture flow conditions at the ground surface. Both the infiltration of water and the exfiltration during evaporation (as well as evapotranspiration) are subject areas of great interest to practicing geotechnical engineers. These conditions are closely related to our understanding of the impact of climate change. It is through the ability to mathematically quantify water balance conditions at the ground surface that the effects of climate change can be taken into consideration through numerical modeling studies. In my estimation, the characterization of fissured, fractured and cracked soil masses near the ground surface, and the quantification of ground surface moisture flux conditions are two of the main topics requiring further research in unsaturated soil mechanics.

历史上有两个主要主题在古典土壤力学的教科书中被封为。也就是说，不饱和土壤的行为和地面上的水分通量条件的定量。在过去的40年中，我们对不饱和土壤力学的理解迅速发展，因为它适用于相对均匀的连续性。有;但是，不饱和土壤力学的两个方面非常需要进一步的研究。第一个方面涉及地面附近土壤条件的结构表征。这些土壤通常包含广泛的裂缝，裂缝和裂缝，从而显着影响不饱和土壤的特性。有人提出，通过使用双峰数学函数来表征这些土壤的二级宏结构。有人提出，存在一个与宏观结构特征相关的空气进入值，而另一个与土壤完整基质相关的空气进入值。因此，靠近地面的不饱和土壤成为双峰，非线性和滞后。在润湿和干燥过程中，许多这些土壤也会显示出显着的体积变化。需要研究的不饱和土壤力学的第二个方面是定量地面上的水分流条件。蒸发期间的水和渗出液的渗透（以及蒸散液）都是实践岩土工程师引起的极大兴趣的主题。这些条件与我们对气候变化影响的理解密切相关。通过数学上量化地面水平状况的能力，可以通过数值建模研究来考虑气候变化的影响。据我的估计，地面附近裂缝，断裂和破裂的土壤质量的表征以及地面水分通量条件的定量是两个主要主题，需要进一步研究不饱和的土壤力学。