Field survey and characterization of southern Ontario tills and St. Lawrence Valley marine clays****

第四纪冰川沉积物覆盖了安大略南部的大部分地区和圣劳伦斯山谷的冰碛物或海洋细粉。 由于河流水流与河床和河岸沉积物的相互作用，切割成这些物质的河流表现出特殊的地貌行为。土木工程（如水坝、桥墩等），旁边（线性基础设施，如公路、铁路等）或跨越（例如桥梁等）这些河流必须考虑这些粘性沉积物的侵蚀，特别是在河流水流被建筑物改变的情况下。 目前对这些物质的侵蚀阈值和侵蚀速度知之甚少，也不了解它们的地理分布以及不同地层和矿床之间的物质特性范围。这就给水利、岩土工程、运输和结构工程项目带来了设计挑战和长期维护考虑，可能导致生命周期成本增加，并可能因意外侵蚀而发生故障。 最近对许多已完成的项目进行的勘察表明，需要对几个地点进行紧急干预，因为这些地点的积极侵蚀已对人员造成安全问题，如果侵蚀在不久的将来继续下去，可能造成环境和经济损失。拟议的研究将通过实地调查确定侵蚀过程的特征，并从收集的土壤样品中确定沉积物内部和内部材料的标准岩土参数的范围和可变性，从而提高对评估和预测河流在冰川冰碛和海洋粘土中的侵蚀过程的认识。该项目将有助于确定由于冰川冰碛或海洋粘土的存在而具有潜在设计挑战的项目，从而降低设计风险和成本。知识的增加将提高专家知识，培训年轻的工程师，同时咨询公司将能够更有竞争力地投标，客户将以更低和更可预测的成本改善项目的长期管理。

Quaternary glacial deposition has covered much of southern Ontario with tills and the Saint Lawrence Valley with glaciolacustrine or marine fines. Rivers incised into these materials exhibit particular geomorphologic behavior due to the interaction of the river flows with the bed and bank sediments. Civil engineering works built either in (e.g. dams, bridge piers, etc.), beside (linear infrastructure such as roads, railways, etc.) or across (e.g. bridges, etc.) such rivers must consider the erosion of these cohesive sediments particularly where river flows are modified by built structures. There is currently very little knowledge about the threshold and rate of erosion of these materials, nor about their geographic distributions and the range of material properties between different strata and deposits. This leads to design challenges and long-term maintenance considerations for hydraulic, geotechnical, transportation and structural engineering projects that can result in increased lifecycle costs and the potential for failure due to unexpected erosion. Recent reconnaissance surveys conducted for many completed projects have indicated that urgent intervention was required at several locations where active erosion had caused safety issues for personnel and could cause environmental and economic losses if erosion were to continue in the near future. The proposed research will develop the improved understanding required to assess and predict erosion processes of rivers in glacial tills and marine clays for built structures by characterizing the erosion process from field surveys and determining, from collected soil samples, the range and variability of standard geotechnical parameters of the materials both inter and intra-deposits. This project will help identify projects with potential design challenges due to the presence of glacial tills or marine clays, allowing for designs with a lower risk and lower costs. The increased knowledge will improve expert knowledge and train young engineers, while consulting companies will be able to bid more competitively and clients will have improved long-term management of projects with lower and more predictable costs.****************