Climatological influences of deep seated translational landslides in residual clay shale bedrock

缓慢移动的山体滑坡给公路和铁路等高价值基础设施带来了巨大的经济风险。两个具体的例子包括具有战略意义的加拿大西部交通走廊，如萨斯喀彻温省的耶洛黑德公路和不列颠哥伦比亚省(BC)的汤普森河谷铁路走廊。这些地点的持续流动正在造成维护费用增加的风险，以及与斜坡移动后基础设施关闭相关的经济损失。这项拟议的研究将探索与这些滑坡有关的两个关键破坏机制的相互作用：预剪切基岩的行为和气象效应对逐渐软化导致的延迟破坏的影响。半干旱气候容易受到孔隙压力动态的大幅波动，并在净渗入深层地下水系统的速度上产生季节性或年际脉冲。对于大型、深层平移滑坡来说，这些孔压动态对破坏表面发展的影响还没有被很好地理解。这些气候驱动的孔压动态往往与沿线建设交通基础设施的深深切割的河谷的水位波动一起加剧。这些循环的孔隙水压力会导致应变软化，导致斜坡的渐进式位移。虽然当水位上升时，毗邻斜坡的河流水位可以提供稳定的附加力，但它也会导致斜坡内孔隙压力的积累，其消散速度比洪峰事件后河流水位随后的下降要慢得多。拟议的研究将结合现场测试和监测、实验室测试和数值模拟，旨在表征萨斯喀彻温省中部和卑诗省中部非常缓慢移动的山体滑坡的地面运动。当局会在斜坡内安装仪器，以补充现有的监察工作。将使用概念(定性)和数值(定量)模型来证明孔压动态与河流侵蚀之间的联系，说明应变的演变和滑坡体稳定性的变化。

Slow-moving landslides present large economic risks to high-value infrastructure such as roadways and railways. Two specific examples include strategic Western Canadian transportation corridors such as the Yellowhead Highway in Saskatchewan and the Thompson River Valley rail corridor in British Columbia (BC). Ongoing movements at these locations are creating risks in terms of increased maintenance costs, and economic losses associated with infrastructure closure following slope movement. This proposed research will explore the interactions of two key failure mechanisms associated with these landslides: the behaviour of pre-sheared bedrock and the influence of meteorological effects on delayed failure resulting from progressive softening. Semi-arid climates are subject to wide swings in pore-pressure dynamics and produce seasonal or inter-annual pulses in the rates of net percolation into deeper groundwater systems. The impact of these pore-pressure dynamics on the development of failure surfaces is not well understood for large, deep-seated translational landslides. These climate-driven pore-pressure dynamics are often compounded by fluctuations of the water levels in deeply incised river valleys along which transportation infrastructure is constructed. These cyclic pore-water pressures can result in strain softening, leading to progressive displacement of the slope. Although the river level adjacent to the slope can provide a stabilizing surcharge force when the water level is elevated, it can also result in pore pressure build up within the slope, which dissipates more slowly than the subsequent drop in river levels following peak flood events. The proposed research will incorporate a combination of field testing and monitoring, laboratory testing, and numerical modelling designed to characterize the ground movement of very slow-moving landslides in central Saskatchewan and central BC. Instrumentation will be installed within the slopes to supplement existing monitoring. Conceptual (qualitative) and numerical (quantitative) modelling will be used to demonstrate the linkages between pore-pressure dynamics and river erosion on the evolution of strain and changes in the stability of the slide mass.