Many desert expressways are affected by the deposition of the wind-blown sand, which might block the movement of vehicles or cause accidents. W-beam central guardrails, which are used to improve the safety of desert expressways, are thought to influence the deposition of the wind-blown sand, but this has yet not to be studied adequately. To address this issue, we conducted a wind tunnel test to simulate and explore how the W-beam central guardrails affect the airflow, the wind-blown sand flux and the deposition of the wind-blown sand on desert expressways in sandy regions. The subgrade model is 3.5 cm high and 80.0 cm wide, with a bank slope ratio of 1:3. The W-beam central guardrails model is 3.7 cm high, which included a 1.4-cm-high W-beam and a 2.3-cm-high stand column. The wind velocity was measured by using pitot-static tubes placed at nine different heights (1, 2, 3, 5, 7, 10, 15, 30 and 50 cm) above the floor of the chamber. The vertical distribution of the wind-blown sand flux in the wind tunnel was measured by using the sand sampler, which was sectioned into 20 intervals. In addition, we measured the wind-blown sand flux in the field at K50 of the Bachu-Shache desert expressway in the Taklimakan Desert on 11 May 2016, by using a customized 78-cm-high gradient sand sampler for the sand flux structure test. Obstruction by the subgrade leads to the formation of two weak wind zones located at the foot of the windward slope and at the leeward slope of the subgrade, and the wind velocity on the leeward side weakens significantly. The W-beam central guardrails decrease the leeward wind velocity, whereas the velocity increases through the bottom gaps and over the top of the W-beam central guardrails. The vertical distribution of the wind-blown sand flux measured by wind tunnel follows neither a power-law nor an exponential function when affected by either the subgrade or the W-beam central guardrails. At 0.0 H and 0.5 H (where H =3.5 cm, which is the height of the subgrade), the sand transport is less at the 3 cm height from the subgrade surface than at the 1 and 5 cm heights as a result of obstruction by the W-beam central guardrails, and the maximum sand transportation occurs at the 5 cm height affected by the subgrade surface. The average saltation height in the presence of the W-beam central guardrails is greater than the subgrade height. The field test shows that the sand deposits on the overtaking lane leeward of the W-beam central guardrails and that the thickness of the deposited sand is determined by the difference in the sand mass transported between the inlet and outlet points, which is consistent with the position of the minimum wind velocity in the wind tunnel test. The results of this study could help us to understand the hazards of the wind-blown sand onto subgrade with the W-beam central guardrails.

中文翻译：

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W型梁中央护栏对沙区沙漠高速公路风沙沉积的影响

许多沙漠高速公路受到风沙沉积的影响，可能会阻碍车辆行驶或引发事故。用于提高沙漠高速公路安全性的W型梁中央护栏被认为会影响风沙的沉积，但尚未得到充分研究。针对这一问题，我们进行了风洞试验，以模拟和探索W型梁中央护栏如何影响沙地沙漠高速公路上的气流、风沙通量和风沙沉积。路基模型高3.5cm，宽80.0cm，岸坡比为1：3。W 型梁中央护栏模型高 3.7 厘米，其中包括一根 1.4 厘米高的 W 梁和一根 2.3 厘米高的立柱。风速是通过使用放置在房间地板上方九个不同高度（1、2、3、5、7、10、15、30 和 50 厘米）的皮托静压管来测量的。风洞内风沙通量的垂直分布采用沙采样器进行测量，采样器分为20个区间。此外，我们于2016年5月11日在塔克拉玛干沙漠巴楚-莎车沙漠高速公路K50现场测量了风沙通量，使用定制的78厘米高梯度沙采样器进行沙通量结构测试. 路基的遮挡导致在路基迎风坡脚下和背风坡处形成两个弱风带，背风侧风速明显减弱。W型梁中央护栏降低背风风速，而速度通过底部间隙和 W 型梁中央护栏的顶部增加。风洞测得的风沙通量的垂直分布在受路基或W型梁中央护栏影响时既不服从幂律也不服从指数函数。在 0.0 H 和 0.5 H（其中 H = 3.5 cm，这是路基的高度），由于 1 和 5 cm 高度的沙子运输，距离路基表面 3 cm W型梁中央护栏，最大输沙发生在受路基表面影响的5厘米高度处。W 型梁中央护栏存在时的平均跃移高度大于路基高度。现场试验表明，W型梁中央护栏超车道背风处有砂沉积，沉积砂的厚度由进、出口点输送的砂质量差决定，与风洞试验中最小风速的位置。本研究的结果可以帮助我们了解风沙对W型梁中央护栏路基的危害。