Mechanical design of transportation embankments built on thawed permafrost

冻土融化交通路基的力学设计

• 批准号: RGPIN-2021-02991
• 负责人: Dumais, Simon
• 金额: $ 1.89万
• 依托单位: Université Laval
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=749464
• 关键词: Mechanical; design; transportation; embankments; built

Transportation infrastructure is essential for the socio-economic development of Canada's North and for the quality of life of its inhabitants. However, transportation embankments inevitably affect the thermal regime of the permafrost by changing the surface conditions. The magnitude of the damages associated with thaw degradation of the permafrost depends on its thaw sensitivity and its ice content. The conservative design approach is to increase embankment height to keep the permafrost frozen such that the thaw front is contained within thaw stable materials. This approach requires large quantities of quality granular material which is economically and logistically challenging in addition to causing major strain on the environment. This conservative design approach is not always warranted. Indeed, when permafrost that does not contain excess ice, deformations due to thaw consolidation are limited. In such cases, the embankment height can be reduced to minimize the quantity of granular materials used in the construction. The thaw penetration thus exceeds the embankment thickness and stress from traffic loads are transferred to the thawed subgrade. Also, existing infrastructure is affected by climate change such that previously thermally stable embankments can become unstable. A mechanical pavement design methodology is thus required to prevent failure by exceeding the limit values for structural and functional conditions for new and existing infrastructure. The proposed research program aims at the development of engineering tools and methods adapted to climate change for the optimization of the mechanical design for the management of transportation embankments built on a permafrost subgrade. Six (6) graduate students will be trained in this research program as they will gain expertise in permafrost and cold regions geotechnical and transportation engineering. The methodology of the project includes the monitoring of a currently established mechanical test section along the Inuvik-to-Tuktuyatuk highway. The data acquired at the test section will be used to develop and calibrate numerical models to support the development of a design methodology. Laboratory testing of intact and artificial permafrost soils will be performed to characterize the mechanical properties of the permafrost. The results will be used in combination with an existing database of more than 300 thaw consolidation tests to develop relationships for the thaw consolidation behavior coupled with the mechanical properties of thawed permafrost. On a larger scope, the research program will contribute to increasing the understanding of the interaction between infrastructure, permafrost, and climate change.

交通基础设施对于加拿大北部的社会经济发展及其居民的生活质量至关重要。然而，交通运输不可避免地通过改变地表条件来影响多年冻土的热状况。与冻土融化退化相关的损害程度取决于其融化敏感性和含冰量。保守的设计方法是增加路堤高度，以保持永久冻土冻结，使解冻前沿包含在解冻稳定材料中。这种方法需要大量优质颗粒材料，除了对环境造成重大压力外，还在经济和后勤方面具有挑战性。 这种保守的设计方法并不总是有保证的。事实上，当永久冻土不包含多余的冰，由于解冻固结变形是有限的。在这种情况下，可以降低路堤高度，以最大限度地减少施工中使用的粒状材料的数量。因此，解冻渗透超过路堤厚度，并且来自交通荷载的应力被转移到解冻路基。此外，现有的基础设施受到气候变化的影响，使得以前热稳定的设施可能变得不稳定。因此，需要一种机械路面设计方法，以防止因超过新的和现有基础设施的结构和功能条件的极限值而发生故障。 拟议的研究计划旨在开发适应气候变化的工程工具和方法，以优化永久冻土路基上建造的运输工具管理的机械设计。六（6）名研究生将在本研究计划中接受培训，因为他们将获得永久冻土和寒冷地区岩土工程和交通工程方面的专业知识。该项目的方法包括监测目前沿Inuvik至Tukatuk高速公路沿着建立的机械测试路段。在试验段获得的数据将用于开发和校准数值模型，以支持设计方法的开发。将对完整的和人造的永久冻土进行实验室测试，以表征永久冻土的机械性能。结果将被用于与现有的数据库的300多个解冻固结试验，以开发的解冻固结行为与解冻多年冻土的力学性能相结合的关系。在更大的范围内，该研究计划将有助于增加对基础设施，永久冻土和气候变化之间相互作用的理解。