Soil-structure interaction and pre-failure deformation with reference to material degradation

岩土工程中与基础设施有关的土-结构相互作用问题，如水坝、公路路面和市政公用设施，包括污水和供水管道，是极其重要的。虽然适当的设计可以将由于土壤强度不足而导致的破坏风险降低到可接受的水平，但重复施加低于土壤强度的应力和/或环境变化引起的土壤退化可能会导致土壤的累积变形，从而影响建立在土壤上/土壤中的基础设施的功能。例如，由于重复的交通负荷和季节性环境变化（如湿度和温度），颗粒基/底基材料和路基土壤的退化每年要花费数百万美元来维持加拿大高速公路的良好状态。提出的研究的主要目的是研究（重复）应力和环境变化下土壤的破坏前变形和退化，以及它们对土壤上建造的结构功能的影响。本研究包括试验研究和计算机模拟土的行为和土-结构相互作用。将使用诸如磁共振成像（MRI）之类的图像技术来测量和可视化土壤行为的退化，同时将开发数值模型来模拟土壤退化引起的结构性能变化。该研究的独特之处在于，在分析土壤-结构相互作用时，它考虑了与循环载荷和环境变化相关的材料退化。研究结果将为可靠和经济的结构设计以及受各种应力和环境条件影响的现有基础设施的修复提供有效的工具。这项工作将涉及研究生，他们将在项目结束时成为高素质的研究人员。

Soil-structure interaction problems in geotechnical engineering related to infrastructure, such as dams, highway pavements, and municipal utilities including sewage and water supply pipelines, are extremely important.  While appropriate designs reduce the risk of failure due to insufficient soil strength, to an acceptable level, a repetitive application of stresses lower than the soil strength and/or soil degradation induced by environmental change may induce accumulative deformation of the soil, and hence affect the function of infrastructure built on/in the soil. For example, degradation of granular base/subbase materials and subgrade soils owing to repetitive traffic loading and seasonal environmental change (e.g., moisture and temperature) costs millions of dollars every year to maintain Canadian highways in good condition. The main objectives of the proposed research are to investigate pre-failure deformation and degradation of soils subjected to (repetitive) stresses and environmental change, as well as their influence on the function of structures built on the soil. This research consists of both experimental study and computer modelling of soil behaviour and soil-structure interaction. Degradation of soil behaviour will be measured and visualized using image techniques such as Magnetic Resonance Imaging (MRI), while numerical models will be developed to simulate the variation of performance of structures induced by soil degradation. The proposed research is unique in that it accounts for material degradation related to both cyclic loading and environmental change when analyzing soil-structure interaction. The results will provide effective tools for reliable and economic design of structures as well as rehabilitation of existing infrastructure subjected to various stress and environmental conditions. The work will involve graduate students who will become highly qualified researchers at the end of the program.