风沙流对铁路涵洞响应规律的三维仿真分析

Three-dimensional Simulation Analysis of Response Law of Wind-blown Sand Flow around the Railway Culvert

研究目的:当风沙流途经铁路涵洞时,风场受到扰动,风沙流平衡状态发生改变,很容易在其附近发生风积沙,导致部分涵洞被积沙堵塞,不仅增加养护难度,而且在雨季山洪爆发时极有可能冲毁线路,危及列车的安全运营。因此,为解决涵洞沙害对线路的危害,本文基于欧拉双流体三维模型,对涵洞周围风沙两相流运动特性进行数值仿真分析,剖析涵洞沙害形成机理。研究结论:(1)模拟结果与现场实际调查相吻合,模型能够较好地反映涵洞周围风沙两相流运动特性;(2)涵洞上部的路堤顶面与涵洞内部处于风蚀区,迎风侧路肩附近风蚀作用明显强于背风侧路肩处;(3)涵洞入口、出口八字墙附近处于风积区,出口处风积作用明显强于入口处;(4)涵洞轴线处气流波动指数呈"先减小,后增大,再减小"的趋势,在迎风侧坡脚处出现最小值(减幅可达21%),在涵洞入口处出现最大值(增幅可达58%);(5)单风向地区,涵洞积沙从出口处开始,多风向地区积沙从两侧洞口开始;(6)多风向地区风积沙堵塞涵洞的周期小于单风向地区;(7)该研究结果对涵洞沙害防治具有指导意义。

Research purposes： Wind field is disturbed so that balanced state of wind - blown sand flow changes when wind - blown sand flow is passing through the railway culvert which is easy to form wind - drift sand so as to block a part of culverts. These not only increase the difficulty of maintenance, but also likely destroy the line when flash floods occur in the rainy season, and endanger operation of the train. Therefore, in order to solve the culvert sand damage to lines, the motion characteristics of wind- blown sand flow around the railway culvert were simulated by the Euler two -fluid three - dimensional model, and the forming mechanism on sand damage of culverts was analyzed in this paper. Research conclusions： （ 1 ） The simulation results are in conformity with field investigations. The model can well reflect the motion characteristics of wind - blown sand flow around the railway culver. （2） The top surface of the embankment and the interior of the culvert is in the wind erosion area, wind erosion near the windward side shoulder is stronger than the road shoulder near the leeward side. （3） The wing wall near culvert inlet and outlet is wind - drift area, wind deposition of outlet is stronger than inlet. （4） Airflow fluctuation index of culvert axis shows a trend of ＂first decreases, then increases and decreases again＂, which reaches minimum value（a decrease of up to 21% ） in the windward slope toe and maximum value（a increase of up to 58% ） at inlet of the culvert. （5） In single wind areas, driftsand starts from the outlet of culvert and in the multi wind direction areas, drift-sand starts from two sides. （6） The period of drift - sand in the multi wind direction areas is smaller than single wind direction areas. （7） The research results have a guiding significance for prevention and control of sand damage of culverts.