Effect of climate on internal erosion in embankment dams and flood defences

内部侵蚀是指土壤从土工结构（如堤防和堤坝）内部因渗水而被侵蚀。无论是在世界范围内还是在英国，它都是大坝和防洪堤失败的两个最常见原因之一。更潮湿的冬季将导致河流流量峰值急剧增加，夏季干旱的风险增加，随之而来的对流风暴将增加山洪暴发的发生，这意味着水坝和防洪堤将承受更大的水力负荷。建造它们的土壤也将受到与蒸发和降雨增加有关的更大的干湿循环。这种循环对土壤抗侵蚀能力的影响尚不清楚。这项研究将首次研究这种气候过程如何影响内部侵蚀。结果将被放置在一个非饱和土壤力学框架内，以便深入了解气候变化的影响，以及驱动这些影响的具体机制。这些数据将用于创建一个基于科学的预测模型，以预测这些土壤在受到气候周期影响时可能如何恶化。实验研究的假设是：气候引起的干湿循环会导致路堤填土材料的劣化，导致其抗侵蚀能力降低。受影响的基础设施将包括英国的堤坝和防洪堤。这样的周期一直在发生，但由于气候变化，其严重程度可能会增加。该项目的具体目标是：1)建造并投入使用最先进的孔蚀测试装置（HET）。HET是一种测定路堤土抗侵蚀能力的实验技术，是这方面应用最广泛的研究工具。模型土壤的测试结果将以其他小组公布的结果为基准。2)受试者填入湿润和干燥路径，以模仿真实堤防中的路径。真实的路堤填充物和实验室土壤与英国大坝的敏感材料具有相似的特征，将进行测试。该方法应该是可重复的，并且产生的样品在密度和含水量方面是均匀的。3)进行一系列HET测试，以获得描述土壤抗侵蚀能力的高质量数据，这些土壤是：(i)压实和（ii）压实后的湿/干路径。4)建立一个预测模型，预测路堤材料的抗侵蚀能力在其使用寿命期间可能发生的变化。这将把可测量的土壤特性与从压实状态到抗侵蚀能力的变化联系起来。

Internal erosion occurs where soils are eroded from within geotechnical structures such as embankment dams and levees by water seepage. It is one of the two most common causes of failure in dams and levees, both worldwide and in the UK. Wetter winters will lead to dramatic increases in peak river flows and the increased risk of summer drought followed by convective storms will increase the occurrence of flash floods, meaning that dams and levees will be subject to greater hydraulic loads. The soil from which they are constructed will also be subject to greater wetting and drying cycles related to increased evaporation and rainfall. The effect of this cycling on soil erosion resistance is unknown. This research will be the first to study how such climate processes affect internal erosion. The results will be placed within an unsaturated soil mechanics framework to allow a deep understanding of the effect of climate change, and the specific mechanisms which drive these effects. The data will be used to create a science-based predictive model about how these soils may deteriorate when subjected to climatic cycles. The hypotheses for experimental investigation is:- Climate induced wetting and drying cycles will cause deterioration leading to a reduction in the erosion resistance of embankment fill materials. The affected infrastructure will include UK embankment dams and levees. Such cycles have always occurred but their severity is likely to increase due to climate change. The specific Objectives for the project are:1) Construct and commission a state of the art hole erosion testing device (HET). The HET is an experimental technique to determine the erosion resistance of embankment soils and is the most widely used research tool for this purpose. Results of tests on model soils will be benchmarked against other groups' published results. 2) Subject fills to wetting and drying paths to mimic those in real embankments. Both real embankment fills and laboratory soils with similar characteristics to susceptible materials from UK dams will be tested. The method should be repeatable and create samples which are homogeneous in terms of density and water content. 3) Carry out a series of HET tests to obtain high quality data describing the erosion resistance of soils which are: (i) as compacted and (ii) subjected to wetting / drying paths following compaction. 4) Create a predictive model of how the erosion resistance of embankment materials is likely to change over their lifetime. This will link measurable soil properties to the change in erosion resistance from the as-compacted state.