Impact of Extent of Wetting in Arid Region Geotechnical Practice

美国发展最快的10个城市中有8个位于西南部的干旱或半干旱地区。随着预期的增长，需要配套的基础设施，包括地面和地下结构。对于土木工程师来说，对干旱土壤的不同力学行为也有越来越多的认识，包括土壤膨胀、崩塌和湿润引起的边坡失稳问题。一些相关的失败可能是灾难性的。最近对现有非饱和流动模型的评估表明，尽管通过适当的模型校准可以相当准确地模拟入渗速率，但饱和程度和原位应力不能很好地预测。本研究解决了在估计湿润程度和程度以及量化湿润对土壤行为的影响方面改进干旱地区岩土工程实践的需要。工作结果将包括湿润程度和程度的实际设计信封，允许评估由于城市化或灌溉增加而导致的饱和度变化。多学科团队包括来自岩土工程、建筑和地质学的PI。方法包括：(1)大型深场溶渗仪；(2)收集、分析和展示从报告信息和从业人员文件中收集的大量现有岩土和地质环境数据；(3)非饱和土抗剪强度和压缩性对润湿反应的测试，包括孔隙空气和孔隙水压力控制和测量。＊＊＊

9612073 Houston Eight of the ten fastest growing cities in the U.S. are located in the arid or semi-arid regions of the southwest. With the expected growth, there is a need for supporting infrastructure including surface and subsurface structures. For civil engineers, there is also a growing appreciation for the different mechanical behavior of arid soils, including problems with soil expansion, collapse, and wetting-induced slope instability. Some of the associated failures can be catastrophic. Recent evaluations of existing unsaturated flow models demonstrate that, although rates of infiltration can be simulated fairly accurately with appropriate model calibration, the degree of saturation and the in situ stresses are not well predicted. This research addresses the need for improving arid-region geotechnical practice in estimating the degree and extent of wetting, and quantifying the effect of that wetting on soil behavior. The result of work will include practical design envelopes of degree and extent of wetting, allowing the assessment of changes in saturation due to urbanization or increased irrigation. The multidisciplinary team includes PI's from geotechnical engineering, construction, and geology. The methodology includes: (1) large-scale, deep field lysimeters, (2) collection, analysis, and presentation of the extensive existing geotechnical and geoenvironmental data assembled from reported information and practitioners files, and (3) unsaturated soil testing for shear strength and compressibility in response-to-wetting, including pore-air and pore-water pressure control and measurement. ***