风沙流与铁路涵洞的响应规律研究

Research on the Dynamic Response of Sand Flow and Railway Culvert

研究目的:在风沙灾害多发地区,携沙气流途经铁路涵洞时,受边界效应和狭管加速效应影响,气流会出现明显的扰动,在涵洞周边出现一系列的沙物质蚀积变化,严重时会堵塞桥涵,危及线路安全。针对上述问题,本文采用数值模拟和现场试验相结合的研究方法,研究涵洞风沙灾害形成的机理,对于减缓既有铁路涵洞沙害和新线设计具有重要意义。研究结论:(1)风沙流途经涵洞时,在涵洞进口内侧会形成一个局部高速涡旋区,之后随着气流的推进,涵洞内的风速开始逐渐消减,但其数值依然略高于来流风速;(2)受狭管加速效应影响,涵洞内风速的垂直梯度差会被放大,出现明显的速度分层现象;(3)风沙流沿导流堤向涵洞口行进过程中,风速呈现缓慢降低的变化趋势,易出现沙粒沉降现象;(4)受构筑物形态影响,涵洞进出口的风速曲线呈现开阔的拱形,涵洞口两侧为明显的低速沉沙区,易发生风沙堆积现象;(5)本研究成果可为铁路沿线涵洞风沙灾害防治提供一定的理论支撑。

Research purposes： In the wind sand disaster areas, when air - sand flow passes through the railway culvert, affected by the boundary effect and narrow tube acceleration effect, the obvious disturbance of airflow appears, and sand will be carried or deposited around the culvert. The accumulation of wind - blown sand in culvert will influence the normal operation of the train. Aiming at the above problem, this paper studied particularly the formation mechanism of wind sand disaster in culvert by using numerical simulation and field test which provides some theoretical basis for disease treatment and railway design.Research conclusions： （ 1 ） The local high - speed vortex area at inlet of culvert is formed, when the air flow passes through the railway culvert. Wind speed gradually decreases with the marching of airflow in culvert, but the value is still slightly higher than the outside wind speed. （2） Due to the affection of accelerating effect, vertical gradient difference will be amplified, and stratification phenomena of speed will appeared. （3） Wind speed decreases gradually, and a large amount of sand fall when wind - sand flow moves along the diversion dike. （4） The curves of wind speed are arch shapes, which are affected by architectural form. The phenomenon of wind - blown sand appears at the both sides of culvert portal, which are the low speed areas of air flow. （5） The research result provides a certain theory support for wind sand disaster prevention of culvert along the railway line.