Defining the operational strength of peat (muskeg)

马斯基土壤和泥炭土覆盖了加拿大陆地面积的18%，主要集中在北部地区。深入了解麝香的工程特性对这些地区交通基础设施的建设和维护非常重要。定义高纤维泥炭的强度仍然是难以捉摸的，因为泥炭线性应变硬化，因此没有发展出可以定义为强度的最大值。此外，用于评估泥炭的传统岩土测试方法无法评估纤维结构产生的拉应力。我的研究和对其他人的研究的回顾导致了高纤维泥炭的假设，包括纤维增强的全部影响，在拉应力状态下失效；在这种应力状态下的试验可以通过扩展应力路径的三轴试验来完成；这种泥炭的强度很难用莫尔-科隆表面来定义。因此，目标1是量化纤维泥炭和纤维加筋土内产生的拉应力；具体地说，纤维中的张力如何被纳入强度并在破坏机制中表现出来。本研究将评估纤维在泥炭和纤维增强粘土中的作用，然后了解纤维土的这种拉伸行为如何表现为承载能力。我以前的博士生和我观察到，在铁路路堤下面的泥炭中，孔隙压力(u)的季节性增加远远超过静水压力，然后迅速下降。研究发现，这是气体生成的结果，并受温度控制。研究发现，气体的存在和孔隙压力的增加会推动流体流动，形成一种热驱动的固结机制，并降低有效强度。这导致了一种假设，即在未来30年里，阿尔伯塔省北部的平均气温将从1.4℃上升到40℃，这将导致更长时间的加速退化和热驱动固结，这种对温度的敏感性有可能对北部基础设施产生负面影响。因此，目标ii是评估泥炭对生气的区域敏感性，从而评估热驱动固结和强度降低；并量化这些地区已经观测到和预测到的气体生成速率对温度升高的敏感性。在研究项目开始时，将对加拿大不同地区的三个地点进行仪器测量，以测量天然气产生的u。数据和热模拟将确定由不同气候变化情景引起的温度分布，并评估加剧降解和伴生气体产生的可能性。这项研究将进一步发展对麝草和泥炭土壤特性的基本理解，从而影响北部地区的发展以及加拿大基础设施的安全性和可靠性。

Muskeg and peat soils cover 18% of Canada's landmass and is primarily concentrated within the northern regions. A strong understanding of the engineering properties of muskeg is important for the construction and maintenance of transportation infrastructure in these regions. Defining the strength of highly fibrous peats is still elusive, as peat linearly strain harden and thus does not develop a maximum value that can be defined as a strength. Further, traditional geotechnical testing methods used to evaluate peat cannot evaluate tensile stresses generated by the fibrous structure. My research and a review of others' led to the hypotheses that highly fibrous peat, inclusive of the full effects of fiber reinforcement, fails at a tensile stress state; testing at this stress state can be accomplished with triaxial tests with extension stress paths; and the strength of this type of peat is poorly defined by a Mohr-Coloumb surface. Thus, Objective i is to quantify the tensile stresses generated within fibrous peat and fiber reinforced soils; specifically, how tension in fibers are incorporated into strength and manifest in the mechanism of failure. This research will evaluate the effects of fibers in peat and fiber reinforced clays, and then develop an understanding of how this tensile behaviour of fibrous soils manifests for bearing capacity. My past PhD student and I observed the seasonal increase of pore pressure (u) in peat beneath railway embankments well above hydrostatic pressure followed by a rapid decrease. This was found to be the result of gas generation and is controlled by temperature. The presence of gas and increased pore pressure was found to push fluid flow as a thermally driven consolidation mechanism and reduce effective strength. This led to the hypothesis that the estimated increases of mean temperature from 1.4oC to > 4oC for northern Alberta over the next 30 years will result in longer periods of accelerated degradation and thermally driven consolidation and that this sensitivity to temperature has the potential to negatively impact northern infrastructure. Thus, Objective ii is to evaluate the regional susceptibility of peat to gas generation and thus thermally driven consolidation and reduced strength; and to quantify the sensitivity of the rate of gas generation to increased temperatures that have been observed and predicted for these regions. Three sites in different regions of Canada will be instrumented to measure u resulting from gas generation at the start of the research program. The data and thermal modeling will determine the temperature profiles resulting from the differing climate change scenarios and evaluate the potential for increased degradation and associated gas generation. This study will further develop a fundamental understanding of the properties of muskeg and peaty soils, and thus impact the development in northern regions and the safety and reliability of Canada's infrastructure.