Design of Geotechnical Infrastructure Using the Mechanics of Unsaturated Soils

在非饱和土力学基础上设计考虑吸力影响的岩土基础设施，可以为加拿大带来显著的经济效益。然而，这种设计方法在传统实践中是有限的。这是因为非饱和土力学理论固有的复杂性，以及耗时的实验研究，需要复杂的测试设备和训练有素的人员。由于这些原因，提出在实践中易于实施的扩展非饱和土力学的设计方法是重要的。为了解决这一迫切需求，申请人将通过本提案专注于三个重要的研究主题。***(i)研究主题一：公路、铁路路面设计；***根据《机械-经验路面设计指南》，路面设计方法分为1级、2级或3级，以满足不同的路面设计标准。第1级方法昂贵且繁琐，需要精心设计的测试设备，而第3级方法本质上是经验的，并且有局限性。为了满足加拿大的路面设计标准，将提出两步方法作为二级方法。考虑到相关的荷载和设计因素，这种方法也可以应用于铁路。***(ii)研究主题二：膨胀土的升沉和膨胀压力随吸力变化的估计；***膨胀土的膨胀压力受湿润引起的土吸力减少的影响。由于膨胀压力的影响，横向和竖向的地面隆起对岩土基础设施的性能都有显著的影响。本文将提出一种基于传统土性质的估算膨胀压力和一维隆起的简单方法。这种技术将引起人们的兴趣，因为它可以用于用膨胀土或在膨胀土中建造的浅层和深层基础的可靠设计。***(iii)研究主题三：膨胀土中膨胀对边坡稳定性的影响；***建议的研究将开发一个数值模拟工具框架，以可靠地设计膨胀土中的边坡，这是最具挑战性的岩土工程问题之一。这个框架也可以通过一些修改扩展到其他有问题的土壤，如加拿大东部的敏感粘土。***申请人通过本提案的长期愿景是为非饱和土壤和其他有问题的土壤（如加拿大的膨胀和敏感土壤）的可持续岩土基础设施的设计做出贡献。目标是提供简单而可靠的解决方案，可用于在实践中以更大程度的信心实施非饱和土壤的力学，同时为加拿大经济做出贡献

Significant economic benefits can be achieved for Canada by designing geotechnical infrastructure based on the mechanics of unsaturated soils, taking account of the influence of suction. However, such design approaches are limited in conventional practice. This is because of the inherent complexity of mechanics of unsaturated soils theory, as well as the time-consuming experimental studies that need elaborate testing equipment and trained personnel. For these reasons, it is important to propose design approaches extending the mechanics of unsaturated soils that are simple for implementing in practice. To address this urgent need, the applicant, through this proposal, will focus on three research themes of significant interest. ***(i) Research Theme I: Design of pavements for highways and railways; ***Pavement design methods as per Mechanistic-Empirical Pavement Design Guide are categorized as Level 1, 2 or 3 to meet the various design standards required for pavements. Level 1 methods are expensive and cumbersome, and need elaborate testing facilities, while Level 3 methods are empirical in nature and have limitations. A two-step approach will be proposed as a Level 2 method for meeting the pavements design standards of Canada. This approach can also be applied for railways, taking into consideration the relevant load and design factors.***(ii) Research Theme II: Estimation of the variation of heave and swelling pressure of expansive soil with respect to suction; ***Swelling pressure associated with expansive soils is influenced by soil suction reduction induced by wetting. Ground heave in both lateral and vertical directions has significant effect on the performance of geotechnical infrastructure due to the influence of swelling pressure. A simple technique will be proposed based on the conventional soil properties for estimation of swelling pressure and 1-D heave. Such a technique will be of interest because it can be used for reliable design of both shallow and deep foundations constructed with or within expansive soils. ***(iii) Research Theme III: The effect of swelling on the stability of slopes in expansive soils; ***The proposed research will develop a framework of numerical modeling tools to reliably design slopes in expansive soils, which is one of the most challenging geotechnical problems. This framework can also be extended with some modifications for other problematic soils, such as the sensitive clays of eastern Canada.***The applicant's long-term vision through this proposal is to contribute to the design of sustainable geotechnical infrastructure in unsaturated soils and other problematic soils such as expansive and sensitive soils of Canada. The goal is to provide simple, yet reliable, solutions that can be used to implement the mechanics of unsaturated soils in practice with a greater degree of confidence, and simultaneously contribute to the Canadian economy.**