高速公路波形梁护栏对风吹雪灾害的影响研究

Study on the snowdrift disaster influenced by w-beam barrier used in expressway

风吹雪是新疆道路交通典型的雪害形式之一,其对道路交通的影响主要体现在降低行车能见度和导致路面大量积雪造成交通中断。新疆地区道路沿线风吹雪灾害呈现出“点多线长面广”且时空分布不均匀的特点,风吹雪涉及到风-雪-温度-湿度等多场耦合,是非常复杂的科学问题。同时,风吹雪灾害防治也是寒区道路交通基础设施建设和运营中亟需解决的实际问题。对于位于风吹雪多发地区的高速公路而言,由波形梁护栏引起的道路风吹雪灾害越来越突出,但目前尚缺乏对波形梁护栏这种高速公路附属设施加深风吹雪灾害的深入研究。针对上述现状,为探究其成因和防治方法,以新疆京新高速公路(G7)为工程背景,设计了波形梁护栏、缆索护栏和无护栏路堤的现场模型试验,并结合数值模拟及公路现场调研等方法,研究了高速公路波形梁护栏和缆索护栏对路面风吹雪灾害的影响,得出设置波形梁护栏和缆索护栏等的路堤路面上的风雪场分布规律。研究结果表明,风雪流从上风侧路堤坡脚处增速,到达设置在路面路肩处或中央分隔带处的波形梁处,通过波形梁护栏下部空隙运动至路面,波形梁护栏对近地面风场产生扰动,使得梁后出现弱风区,导致大量雪粒沉积。尤其当波形梁护栏下部空隙被雪填满后,波形梁后侧的路面积雪覆盖行车道,严重影响公路通行能力,而不设置护栏或者设置缆索护栏的地段有利于风雪流通过。考虑到未来气候变化的不确定性,为更好防范风吹雪对交通运营安全的影响,提出可将部分风吹雪灾害严重地段的波形梁护栏更换为符合高速公路安全要求的缆索护栏的初步建议,也可增设防雪栅、挡雪板及挡雪墙等其他防风雪措施。研究成果可为高速公路运营期间的除雪保畅工作及新疆风吹雪多发地区高速公路的建设提供有益借鉴。

Snowdrift is one of the most typical snow disaster forms of road traffic in Xinjiang area. Its impact on road traffic is mainly reflected in reducing driving visibility and causing traffic interruption induced by a large amount of snow on the road surface. The snowdrift disaster along the road in Xinjiang area shows the characteristics as many points, long lines and wide spread occurring with uneven distribution in time and space. Snowdrift question involves wind field, snow distribution field, temperature field and humidity field coupling, which is a very complex scientific problem. At the same time, the prevention and control of snowdrift disasters is also a practical problem that needs to be solved urgently in the construction and operation of road traffic infrastructure in cold areas. For expressways in areas of frequent snowdrift occurring, its snowdrift disaster caused by the wbeam barrier is becoming more and more obviously. But there is still a lack of in-depth research on the w-beam barrier, which is one kind of auxiliary facilities of the highway deepening the snowdrift disaster. In view of the status mentioned above and in order to explore the causes and prevention methods to snowdrift disaster by wbeam barrier, on the background of Beijing-Urumqi Expressway(G7) engineering, the field model tests of the w-beam barrier, the cable barrier and the no barrier embankment were designed. The study also combined with numerical simulation and highway field investigation and other methods in order to verify each other. In the meantime, the influence of the w-beam barrier and cable barrier on the road snowdrift disaster of the highway is studied, and the distribution law of wind field and snow field on the embankment surface with w-beam barrier and cable barrier is obtained. The results show that the snowdrift velocity increases from the foot of the embankment on the upwind side till to the w-beam barrier installed at the shoulder of or the central divider of the road.Then it moves to the road surface through the gap in the lower part of the w-beam barrier. At this time the wbeam barrier disturbs the wind field near the ground, causing a weak wind area to appear behind the beam, resulting in a large number of snow particles deposited. Especially when the lower gap of the w-beam barrier is filled with snow, the road area behind the w-beam barrier covers the driving lane with snow, which seriously affects the road capacity. While the section without setting up a barrier or setting a cable barrier is conducive to the passage of snowdrift flow. Considering the uncertainty of future climate change, in order to better prevent the impact of snowdrift on traffic operation safety, it is proposed to replace the w-beam barrier in some areas with serious wind and snow disasters with cable barrier that meet the safety requirements of expressways. Moreover, other snowdrift protection measures such as snow fences, snow barriers and snow walls can also be adopted.The research results can provide useful reference for snow removal of the expressway and new expressway construction in the windy and snow areas of Xinjiang.