Riverbed deformation around multiple pile bridge piers under ice-covered conditions - experimental study in a large-scale flume and numerical simulation

冰覆盖条件下多桩桥墩周围河床变形——大型水槽试验研究与数值模拟

• 批准号: RGPIN-2019-04278
• 负责人: Sui, Jueyi
• 金额: $ 2.62万
• 依托单位: University of Northern British Columbia
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=753322
• 关键词: Riverbed; deformation; around; multiple; pile

In Canada, ice cover can last up to six months in some regions. Under ice covered conditions, the location of maximum flow velocity is closer to the riverbed than during open flow conditions. Thus, riverbed scour depth around bridge piers under ice cover is greater than in the absence of ice cover. Excessive scour can cause damage to bridge pier foundations, such as occurred with the collapse of the Highway 16 bridge in Smithers, BC in 1966 and the bridge collapse in Port Bruce, ON in 2018. The proposed research will help us better understand local scour processes around multiple piers with different dimensions, shapes and arrangements under ice cover. This study will provide civil engineers with reliable results that can be used to modify bridge design guidelines that take the impact of ice cover into consideration. This research will address some important gaps in the scientific literature, including, (a) assessing local scour processes around multiple piers under ice cover, (b) investigating the impacts of the dimension/shape/arrangement of multiple piers on local scour processes under ice cover, (c) establishing equations describing the dependence of scour processes on flow intensity, particle size, cover conditions, arrangement of multiple piers, and compressed horse-shoe vortex under ice cover, and (d) developing a numerical model for simulating local scour processes around multiple piers under ice cover. Extensive experiments will be carried out in a large scale flume which is 80-meters long, 2-meters wide and 1.3-meters deep. Five different non-uniform sands will be used. Styrofoam sheets will be used as simulated ice cover (smooth, rough and very rough). Analyses of the experimental data under both open-flow and ice-covered conditions will focus on non-dimensional variables, such as shear Reynolds number, Shields parameter and bridge pier dimensions. Equations will be established to determine the scour depth under ice cover. Modeling the scour process will include modeling a strongly coupled system involving flow field, sediment transport and bed morphology. The numerical model will consist of three modules: a hydrodynamic module for the simulation of the flow field around multiple piers, a sediment module for the modeling of suspended sediment transport, and a bed variation module to account for the change in the bed topography. Numerical studies of the local scour around multiple bridge piers will also be undertaken in the present research. One of the priorities for the simulation of flow fields around multiple bridge piers is to solve the vortex systems around the infrastructure. To solve the vortex systems, either unsteady RANS (Reynolds-averaged Navier-Stokes equations) or Large Eddy Simulation will be used to resolve the horseshoe vortex. The standard k-epsilon turbulence model will be used first in the simulation for the flow field around multiple bridge piers under ice cover. The RNG-based k-epsilon turbulence model will also be used in the simulation.

在加拿大，在某些地区，冰盖最多可以持续六个月。在冰覆盖的条件下，最大流速的位置比开放条件下的河床更靠近河床。因此，在没有冰盖的情况下，冰盖下桥墩周围的河床冲刷深度要大。过度的冲刷可能会损害桥梁码头的基础，例如，1966年，史密瑟斯（Smithers）的16号高速公路桥的倒塌发生，并于2018年在布鲁斯港（Port Bruce）发生桥梁倒塌。拟议的研究将帮助我们更好地了解具有不同维度，冰层和安排不同尺寸的码头周围的地方冲刷过程。这项研究将为土木工程师提供可靠的结果，可用于修改桥梁设计指南，以考虑冰盖的影响。 This research will address some important gaps in the scientific literature, including, (a) assessing local scour processes around multiple piers under ice cover, (b) investigating the impacts of the dimension/shape/arrangement of multiple piers on local scour processes under ice cover, (c) establishing equations describing the dependence of scour processes on flow intensity, particle size, cover conditions, arrangement of multiple piers, and compressed horse-shoe vortex under ice cover, and (d)开发一个数值模型，用于模拟冰盖下多个码头周围的本地冲刷过程。大规模的水槽将进行广泛的实验，该水槽长80米，宽2米，深1.3米。将使用五种不同的非均匀沙子。聚苯乙烯泡沫塑料板将用作模拟冰盖（光滑，粗糙和非常粗糙）。在开放流和冰覆盖的条件下对实验数据的分析将集中在非二维变量上，例如剪切雷诺数，屏蔽参数和桥码头尺寸。将建立方程式以确定冰盖下的冲刷深度。 建模冲洗过程将包括建模涉及流场，沉积物传输和床形态的强耦合系统。数值模型将由三个模块组成：用于模拟多个码头周围流场的流体动力模块，用于建模悬浮沉积物传输的沉积物模块，以及一个床位变化模块，以说明床地图的变化。在本研究中，还将进行多个桥墩周围的当地冲刷的数值研究。模拟多个桥墩周围流场的优先事项之一是解决基础架构周围的涡流系统。为了求解涡流系统，将使用Unsteady Rans（雷诺平均的Navier-Stokes方程）或大型涡流模拟来解决马蹄形涡流。标准的K-Epsilon湍流模型将首先在冰盖下多个桥墩周围的流场的模拟中使用。基于RNG的K-Epsilon湍流模型也将用于模拟中。