Geomechanical Properties of Muskeg (Peat)

加拿大的麝香(泥炭)覆盖的土地比世界上任何其他国家都多，覆盖了18%的土地面积，主要是在该国北部地区。岩土工程中普遍认为，应尽可能避免将其作为基础材料。然而，回避并不总是一种选择，特别是对于线性、连续的结构，如公路、铁路和管道所需的结构。随着资源和基础设施开发的不断扩大，特别是在加拿大北部，预计涉及泥炭的工程项目数量只会增加。在艾伯塔省北部，在马斯凯格建造的较老的基础设施在过去十年中交通量大幅增加，这造成了广泛和持续的稳定和定居点问题。 麝香是在陆化过程中形成的。这一过程始于浅水的边缘，由于水的酸性、缺氧条件和温度，植物物质的腐烂速度被减缓到开始积累和填满湖泊的速度。这导致了一系列泥炭的形成，这取决于积累的植物材料的类型、腐烂状态和获得氧气的途径。麝香被描述为一种“普通的、非凡的物质”(霍布斯1986)。这突出了这样一个事实，即泥炭表现出与矿物(颗粒)土相似的特性和分类特性之间的相关性(因此是普通的)；但这些特性的值与矿物土非常不同(因此是非同寻常的)。这方面的一个例子是泥炭的强度，鉴于其异常高的水分含量，泥炭的强度非常高。马斯凯格火山在空间上以及同一区域内不同地层之间也表现出高度的可变性。由于其复杂的性质，马赛克基础对在其上建造的基础设施的建设和维护提出了独特的问题。 在申请人以前和现在进行的研究中，发现了对麝香的基本工程特性理解方面的几个重要差距。这些差距包括：1)马赛克特性变化的量化，以及这对选择马赛克特性用于基础设施建设和修复的影响；2)马赛克在路堤荷载下的随时间变化的变形行为模型，导致大的沉降；以及3)马赛克的各向异性强度和刚度特性的完整表征，这是确定马赛克地基稳定性的基础。这项研究的结果有望有助于提高加拿大基础设施的安全性和可靠性，通过更好地预测穆斯克格的性能来降低建筑成本，并减少目前在穆斯凯格上建造的结构的维护要求。

Canada has more muskeg (peat) covered land than any other country in the world, covering 18% of the land area, primarily in northern areas of the country. The common view of muskeg in geotechnical engineering is that it should be avoided as a foundation material whenever possible. However, avoidance is not always an option, particularly for linear, continuous structures such as those required for roads, railways and pipelines. As resource and infrastructure development continues to expand, particularly in northern Canada, it is anticipated that the number of engineering projects involving peat will only increase. In northern Alberta, older infrastructure constructed over muskeg has been subjected to large increases in traffic over the past decade, and this has resulted in widespread and ongoing stability and settlement issues. Muskeg forms by the process of terrestrialization. This process starts at the margins of a shallow body of water, and due to the acidity, anoxic conditions and temperature of the water, the decay of the plant material is slowed to a pace at which it begins to accumulate and fill in the lake. This results in a range of peat formations, depending on the type of accumulated plant material, the state of decay and the access to oxygen. Muskeg has been described as an “ordinary extraordinary material” (Hobbs 1986). This highlights the fact that peat exhibits similar traits and correlations between geotechnical engineering properties and classification properties as mineral (particulate) soils (and thus ordinary); but with values for these properties that are greatly different from mineral soils (thus extraordinary). One example of this is the strength of peat, which is remarkably high given its exceptionally high water content. Muskeg also demonstrates a high degree of variability spatially as well as between different formations within a single region. Due to its complex nature, muskeg foundations pose unique problems for construction and maintenance of infrastructure constructed on top of it. Several important gaps in the understanding of the fundamental engineering properties of muskeg were identified during previous and current research conducted by the applicant. These gaps include 1) a quantification of the variability of muskeg properties, and the effect of this on the selection of muskeg properties for the construction and remediation of infrastructure; 2) a model for the time-dependent deformation behaviour of muskeg under embankment loading which results in the large settlements; and 3) a complete characterization of the anisotropic strength and stiffness properties of muskeg which are fundamental to the determination of the stability of muskeg foundations. The results of this research are expected to contribute to the safety and reliability of infrastructure in Canada, reduce construction cost by the better prediction of the properties of muskeg and a reduction of the maintenance requirements for the structures currently constructed on muskeg.