Performance Evaluation of Critical Geosystems Using Multiscale Methods

世界各国依靠各种岩土基础设施进行防洪、蓄水和水力发电。这些关键的地质系统通常涉及多孔介质与结构元件的相互作用，如溢洪道墙、与出口工程相关的管道或毗邻的支撑堤防的重力结构。在洪水期间的高水位或在没有明显触发事件的正常运行条件下，防洪堤或堤防大坝的内部侵蚀可能会发生破坏。后者可归因于各种因素，包括现有树根的腐烂或入侵的野生动物活动，导致防洪堤或堤坝内的局部空洞一直隐藏，直到土结构的安全受到威胁。在世界范围内，由于这些因素造成的土质结构破坏的平均成本每年超过数十亿美元。在土工系统中，土壤劣化和与侵蚀有关的破坏的负面影响不仅限于土工结构。现有建筑物下面或附近的管道泄漏也会引起突然的、不为人知的故障。***在加拿大，一些地区容易发生洪水，这在很大程度上是由于丰富的水资源和极端的季节性温度。人们对完整土质结构进行了广泛的研究，以研究管道、侵蚀和漫顶的机理。然而，关于土结构在(a)局部土壤劣化或(b)嵌入结构单元的破坏机制的综合研究在文献中非常缺乏。***目前的工程工具和程序在模拟流动水、土壤介质和嵌入结构之间相互作用的动力学方面非常有限。为了解决这个问题，目前的工作将发展一种严格的多尺度方法，以提供尽可能多的信息，合理可行的关于这个复杂的土壤-水-结构相互作用问题。这项发现补助金的主题涉及开发新的工程工具，以评估极端条件下使用离心机实验和多尺度建模方法的关键岩土结构的性能。这项研究计划的结果将有助于工程师和研究人员评估现有土坝和堤防的安全性。它也将解释土壤不稳定和破坏与泄漏管道埋在近地表和地下结构。***上述研究项目将在五年的资助期内培养四名硕士和五名博士研究生以及五名暑期本科生。即将毕业的岩土工程师将对实验研究和复杂建模的重要性（和局限性）有一个平衡的看法，并将成为加拿大和国际科学界的真正财富。

Countries around the world rely on various geotechnical infrastructure for flood control, water storage and hydroelectric power generation. These critical geosystems typically involve a porous media interacting with structural elements such as spillway walls, conduits associated with outlet works or adjoining gravity structures supporting the embankment. The failure of levees, or embankment dams by internal erosion may occur under high water levels during flood events or under normal operating conditions without an apparent triggering event. The latter can be attributed to various factors including decay of existing tree roots or invasive wildlife activities that result in local voids within levees or embankment dams that remain concealed until the safety of the earth structure is jeopardized. The worldwide average cost of failed or damaged earthen structures due to these factors exceeds billions of dollars per year. The negative impact of soil deterioration and erosion-related failure in geosystems is not limited to earth structures. Leaking pipes under or near existing structures are also known to cause sudden and unnoticed failure. ***In Canada, several regions are prone to flooding due, in large part, to the abundance of water resources and the extremes in seasonal temperatures. Extensive research has been done on intact earth structures to study the mechanisms of piping, erosion, and overtopping. However, studies related to the synthesis of failure mechanisms of earth structures with either (a) local soil deterioration, or (b) embedded structural elements are very scarce in the literature.***Current engineering tools and procedures are very limited in modeling the dynamics of the interaction between the flowing water, the soil media and embedded structures. To address this issue, the present work will develop a rigorous multiscale approach to provide as much information as reasonably feasible about this complex soil-water-structure interaction problem. The theme of this Discovery Grant relates to developing new engineering tools to assess the performance of critical geotechnical structures under extreme conditions using centrifuge experiments and multiscale modeling approaches. The outcome of this research program will help engineers and researchers to evaluate the safety of existing earth dams and levees. It will also explain the soil instability and failure associated with leaking pipes buried near surface and subsurface structures. ***The above research program will involve training of four Master and five Doctoral students in addition to five summer undergraduate students over the five year funding period. The graduating geotechnical engineers will have a balanced outlook on the importance (and limitations) of experimental research and sophisticated modelling, and will be a real asset to the scientific communities in Canada and internationally.