兰新二线挡风墙下部开口疏导线路积沙试验

摘要

Research purposes:Part of Lanzhou -Xinjiang Railway second line is located on the wind area of Gobi desert which has characteristics of drought,lack of rain and loose stratum,which form easily strong sand flow under strong wind.In order to protect the safety of train operation,windbreak was built in shoulder which well played the windbreak effect.But with layout of windbreak,when sand flow passes roadbed,the ability of carrying sand reduces so that some sands fall and heap up shoulder or ballast bed,which cause serious harm of route eolian -sand.In order to solve difficult problem of route eolian -sand along Lanzhou -Xinjiang Railway second double line and ensure the safety of train operation,this paper discusses experiment feasibility which base on engineering background of experiment on dredging route eolian -sand by opening at the bottom of windbreak. Research conclusions:(1)Field experiment shows that:the amount of eolian -sand reduces on step of subgrade support layer and increases on rail board of uplink after opening windbreak.Existing route eolian -sand merely is secondly transported and redistributed by wind power.The opening of windbreak has not obvious effect for clearing route eolian -sand.(2)Numerical simulation analysis shows that:the lee side of windbreak lies in airflow low speed region before opening.Airflow near step of subgrade support layer lies in airflow acceleration region,but other areas still lie in airflow low speed region.Most particles can again drop near uplink and aggravate amount of eolian -sand on uplink.(3)The experimental results have guiding significance for sand prevention project on ballastless track of high -speed railway.%研究目的：兰新二线部分路段地处戈壁荒漠风区，干旱少雨，地表松散，大风条件下极易形成强风沙流，为保护列车安全运行，在路肩部位设立了挡风墙，起到了较好的防风效果。但随着挡风墙的布设，过境风沙流途经路堤时，气流携沙能力下降，造成部分沙颗粒沉降，堆积在线路路肩及道床上，造成严重的线路积沙危害。为解决兰新二线挡风墙后线路积沙难题，确保列车安全运行，本文以烟墩风区挡风墙下部开口疏导线路积沙进行试验，验证疏导线路积沙的可行性。　　研究结论：（1）现场试验表明：挡风墙开口后，支撑层台阶处积沙量逐渐减少，上行线轨道板上积沙量逐渐增加，风力只是将线路既有积沙进行了二次搬运和再分配，开口对线路积沙疏导效果不明显；（2）数值模拟分析表明：挡风墙开口前背风侧整体处在气流低速区，开口后支撑层台阶附近气流处在加速区，其他区域仍处在气流低速区，大部分沙粒可能重新跌落在上行线附近，加剧上行线积沙量；（3）该研究结果对高速铁路无砟轨道防沙工程具有指导意义。