Dam Seepage Sensing and Modelling

土质堤坝被广泛用于容纳水电站、供水和诸如采矿和油砂作业产生的废物。必须避免通过这种水坝的集中渗水，以防止细颗粒材料的内部侵蚀和管道的发展-这是大坝失败的主要原因。虽然加拿大的水坝标准是世界上最严格的，但随着时间的推移，最佳实践也在不断进步，国际上也认识到需要改进渗漏监测方法，以适用于老化结构。UNB和NB Power将通过实地试验和建模，设计和评估三种微创地球物理方法，用于早期检测和定量浓缩渗水。该项目将基于NB电力公司的Mactaquac发电站，该发电站位于圣约翰河附近的弗雷德里克顿，其中包括一个500米长的分区堤防大坝，于1968年完工，高出其趾32米。这些方法将主要依赖于监测大坝内部的季节性温度变化，如直接使用分布式温度传感（DTS）和间接通过电阻率成像（ERI）测量。渗流程度较高的地区预计会表现出更大的温度季节性变化，因此当大坝水库的水流过它时，电阻率也会更大。特别令人感兴趣的区域包括大坝的粘土核心和大坝毗邻的混凝土导流溢洪道结构的左桥台，该结构由于混凝土中的碱骨料反应性而发生微分膨胀。前者将利用沿坝顶的延时二维电阻率监测进行调查，该监测在瑞典的类似水坝上取得了令人鼓舞的结果。将使用钻孔DTS对坝肩区域进行更详细的调查，并辅以大坝背面电极的延时3D电阻率监测。该研究将建立在先前使用DTS和自我电位（SP）方法在基台区域进行的监测研究中获得的宝贵见解的基础上。它将适用于全球，但特别适用于加拿大等季节性温度变化较大的地区。

Earthen embankment dams are widely used to contain hydroelectric reservoirs, water supplies and wastes such as those produced by mining and oil sands operations. Concentrated water seepage through such dams must be avoided to prevent internal erosion of fine-grained materials and the development of piping - a major cause of dam failure. Although standards for dams in Canada are amongst the strongest in the world, best practices have progressed over time, and the need for improved seepage monitoring methods that can be applied to aging structures is recognized internationally. UNB and NB Power will design and evaluate, through field trials and modelling, three minimally invasive geophysical approaches for the early detection and quantification of concentrated water seepage. The project will be based at NB Power's Mactaquac Generating Station on the Saint John River near Fredericton, NB, which includes a 500 m long zoned embankment dam, completed in 1968, that rises 32 m above its toe. The methods will rely largely on monitoring of seasonal temperature variations within the dam, as measured directly using distributed temperature sensing (DTS), and indirectly by electrical resistivity imaging (ERI). Regions of higher seepage are expected to exhibit greater seasonal variations in temperature and hence resistivity as water from the dam reservoir moves through it. Zones of particular interest include the dam's clay till core and the left abutment where the dam adjoins a concrete diversion spillway structure that is undergoing differential expansion as a consequence of Alkali Aggregate Reactivity in the concrete. The former will be investigated using time-lapse 2D resistivity monitoring along the dam crest which has yielded encouraging results on similar dams in Sweden. The abutment region will be investigated in more detail using borehole DTS complemented by time-lapse 3D resistivity monitoring with electrodes on the back of the dam. The research will build on valuable insights obtained from prior monitoring research in the abutment region using DTS and self-potential (SP) methods. It will be applicable worldwide but particularly in regions such as Canada where seasonal temperature variations are large.