风沙区高等级公路设施与路基高度耦合对气流动力学和蚀积特征的影响

Impacts of Coupled Highway Structures and Roadbed Height on Aerodynamics and Erosion Characteristics in a Windblown Sandy Area

[目的]揭示风沙地区不同高度高等级公路附属设施对过境风沙流的扰动效应,分析不同高度与公路设施影响下的公路路面积沙程度,为公路工程设计和穿沙公路防护措施的制定提供理论依据。[方法]采用了计算流体力学(CFD)数值模拟方法,将普通公路作为对照,对比分析不同路基高度和公路设施组合对近地表过境气流的影响,并通过野外实测数据进行验证。[结果]公路设施显著影响了路基过境气流,导致公路形成减速区,不同高度路基产生多样性的水平气流速度变化。当路基高度在1~2 m之间时,气流扰动较弱,有助于断面输沙;当路基高度在3 m高度时,气流扰动较强,不利于断面输沙。气流穿过护栏和中央隔离带时,气流从护栏下方经过,风速增加,护栏背风侧最大风速的距离随着路基高度的增加呈现先增加再减小的变化趋势,路基高度在0,1,2,3 m时,最大风速距离分别为10,20,25,20 cm。随后在护栏背风侧与上层气流合并,尾流持续扩散,形成减速区,过境气流在该区域发生衰减,沙粒颗粒产生沉积,最高积沙高度11.5 cm,积沙宽度4~4.5 m。[结论]路基高度和公路附属设施是影响公路沿线沙害的主要因素。路基高度对气流到达路基上方的风速产生显著影响,而护栏和防眩网的存在可能在背风侧形成弱风区,从而导致公路上的沙堆积,存在潜在危险。

[Objective]The disturbance effects of accessory facilities of high-grade highways were revealed at different heights in windy and sandy areas on the passing sand flow,the degree of sand deposition on the road surface was explored under the influence of different heights and highway facilities,in order to provide theoretical basis for the design of highway engineering and the formulation of protective measures for sand crossing highways.[Methods]The computational fluid dynamics(CDF)numerical simulation method was used for the analysis,and an ordinary highway was used as a control.The findings regarding the impact of highway structures and different roadbed heights on roadbed transit airflow and the resulting formation of deceleration zones on the highway were validated against field-measured data.[Results]The varying heights of roadbeds resulted in different changes in horizontal airflow velocity.When the height of the roadbed ranged from 1 m to 2 m,the airflow disturbance was relatively weak,thereby facilitating the transport of sand across the highway.In contrast,when the height of the roadbed reached 3 m,the airflow disturbance became stronger,and hindered the transport of sand across the highway.When the airflow traversed the guardrail and the central barrier,it flowed beneath the guardrail,resulting in an increase in wind speed.The distance at which the maximum wind speed occurred on the leeward side of the guardrail initially increased and then decreased with increasing elevation of the roadbed.Specifically,at roadbed heights of 0 m,1 m,2 m,and 3 m,the distances at which the maximum wind speed occurred were measured to be 10 cm,20 cm,25 cm,and 20 cm,respectively.Subsequently,the airflow combined with the upper layer on the leeward side of the guardrail,resulting in continuous diffusion of the tail flow.This led to the formation of a deceleration zone where the transit airflow weakened.As a result,sand particles began to be deposited,resulting in a maximum height of sand accumulation of 11.5 cm.The width of sand accumulation ranged between 4.0 m and 4.5 m.[Conclusion]The height of the roadbed and the presence of road structures were identified as the primary factors contributing to sand damage along highways.Roadbed height had a significant impact on the wind speed above it.The installation of guardrails and anti-glare nets can create a low wind zone on the leeward side of the structures,resulting in sand accumulation on the highway that can pose potential hazards.