Scour at culvert outlets under ice cover and ice jam conditions

在设计和建造公路系统时，主要考虑因素之一是通过涵洞系统输送支流排水。涵洞出口急流冲刷的研究已有几十年的历史。各种研究已经检查了影响侵蚀程度的许多冲刷参数，但是，在寒冷地区涵洞出口设计和冲刷控制方面的研究有限。涵洞可能在冬季严寒气候下完全覆盖进水口，也可能在早春面临冰塞，这可能导致路堤洪水和过度冲刷。此外，由于冰盖和冰塞的存在，涵洞内的流场与明渠条件下的流场有所不同。由于冰盖和冰塞，涵洞出口处的冲刷过度，会导致路堤洪水，从而导致公路失效。覆盖和堵塞的涵洞入口的影响从来没有得到解决的经验。此外，目前还没有可用的实验或数值模拟来研究覆盖条件下涵洞内的流动剖面。本文主要研究了冰盖和冰塞条件下涵洞冲刷的试验和数值模拟。将对以下目标进行评价：a）评估冰盖条件下涵洞出口处的瞬时冲刷发展; B）建立描述冲刷过程对水流强度、涵洞形状、颗粒粒度和边界条件的依赖关系的相关方程; c）确定冰盖和冰塞如何改变非均匀砂中涵洞出口处冲刷坑的几何形状; d）研究冰堵对涵洞出口冲刷的影响; e）建立矩形涵洞出口冲刷过程的数值模拟模型。 本研究将在三个不同的水力水槽中进行小、中、大型试验。试验和数值模拟将产生一组经验方程，用于预测冰况下涵洞出口处的最大冲刷深度。将编写《水利工程涵洞设计与维护综述》。将深入讨论冰盖和冰塞的影响。本研究为解决涵洞出口冲刷问题提供了一种实用的方法。预测涵洞出口处冲刷的大小和几何形状的能力是加拿大沿着公路侵蚀控制和管理中非常有用的评估工具。该研究将有益于实践工程师和科学界。

One of the major considerations in the design and construction of a highway system is the conveyance of tributary drainage through a culvert system. The investigation of scour by swift-flowing water at culvert outlets has been on-going for several decades. Various studies have examined many scour parameters that affect the degree of erosion; however, there is limited research on culvert outlet design and scour control in cold regions. Culverts may become fully inlet-covered in rigid winter climates and may also face ice jamming in early spring, which can result in embankment flooding and excessive scour. Additionally, due to the extra boundary imposed by ice cover and ice jam, the flow field inside the culvert is different from that under open channel conditions. Excessive scour at culvert outlets due to ice cover and ice jamming cancause embankment flooding, which can result in highway failure. Theimpact of covered and jammed culvert inlets has never been addressedexperimentally. Furthermore, there are no available experimental ornumerical simulations to investigate the flow profiles inside theculvert under covered conditions. The research focuses on the experimental and numerical investigation of culvert scour under ice cover and ice jam conditions. The following objectives will be evaluated: a) to assess temporal scour development at culvert outlets under ice cover conditions; b) to establish associated equations describing the dependence of scour processes on flow intensity, culvert shape, particle grain size, and boundary conditions; c) to determine how ice cover and ice jams alter the geometry of scour holes at culvert outlets in non-uniform sands ; d) to investigate the impacts of ice jamming on the scouring at culvert outlets; e) to develop a numerical model for simulating the scour process for rectangular culvert outlets. In the proposed research, small scale, medium scale and large scale experiments will be conducted at three different hydraulic flumes. The experiments, together with numerical simulation, will generate a set of empirical equations that will predict the maximum scour depth at culvert outlets under ice conditions. A compilation of review on culvert design and maintenance in hydraulic engineering will occur. The ice cover and ice jam impacts will be discussed in depth. The present research will provide a practical approach to address the scouring at culvert outlets. The ability to predict the magnitude and geometry of scour at culvert outlets is an extremely useful evaluation tool in the control and management of erosion along highways in Canada. The research will be beneficial to practicing engineers and the scientific community.