沙漠公路风沙流特征及防风挡沙墙研究

发布时间：2018-05-29 15:54

本文选题：沙漠公路 + 风沙流　；参考：《兰州大学》2014年硕士论文

【摘要】：近年来,作为风沙环境工程应用的一个重大问题,戈壁地区沙漠公路风蚀破坏问题受到越来越多的关注。本文通过计算流体动力学软件Fluent6.3,利用标准k-ε湍流模型对沙漠公路路基模型周围的流场进行了数值模拟计算,得出了路基周围的风沙流结构特征,解释了沙粒在加速区对路基体产生风蚀,在减速区形成积沙的原理；利用标准k-ε湍流模型对加了防风挡沙墙后的沙漠公路路基模型周围流场进行了数值模拟计算,并利用离散相模型计算了不同粒径、不同摩阻风速以及挡沙墙不同高度下的沙粒运动轨道,据此分析研究了挡沙墙挡风抑沙的机理和性能,为实际设计和建设防风挡沙墙提供了一些参考和指导。本文的主要内容分为两部分,一是对不同来流风速下的公路路基模型周围流场进行了模拟。二是对防风挡沙墙与公路路基之间的不同距离、不同初始风速和不同防风挡沙墙高度下公路路基模型周围的流场进行了模拟计算,并对不同粒径等三种情况下的沙粒进行DPM(离散相模型)模拟。通过计算,主要结论为： 1.在公路路基周围流场中,迎风坡坡顶处及其上方部分区域内形成相对加速区,对路基产生强烈的风蚀；而在路基上表面、背风坡坡脚和迎风坡坡脚位置处,形成相对低速区,导致沙粒动能减少,跌落到地面,形成积沙。 2.设置挡沙墙后公路路基周围流场发生了显著变化。防风挡沙墙与公路路基合理距离的判断条件为：气流中大多沙粒应该被挡沙墙挡在迎风一侧；在路基迎风侧不出现加速区,不会对路肩产生强烈风蚀,同时要使得风沙流能平稳通过公路路基表面。通过DPM计算了不同粒径、不同摩阻风速以及防风挡沙墙不同高度下的沙粒运动轨迹,我们可以得到对于本文公路路基模型,防风挡沙墙高度为2m,距离公路路基底部为3m时挡沙墙挡沙效果为最佳。 3.在不同的来流风速条件下,高度一定的防风挡沙墙效果是不同的：风速较小时,防风挡沙的效果不明显；风速较大时,墙后的回旋区过大。当风速一定时,随着挡沙墙高度增大,对入口处位置较高的沙粒有明显的加速扬起作用,但对墙后底部的流场及沙粒运动的影响不大。这样我们可以得出：在实际建设中,综合挡沙墙效果和建设成本等要素,防风挡沙墙高度略高于实际公路高度为最
[Abstract]:In recent years, as an important problem in the application of wind-sand environment engineering, the wind erosion damage of desert highway in Gobi area has been paid more and more attention. In this paper, the numerical simulation of the flow field around the roadbed model of desert highway is carried out by using the standard k- 蔚 turbulence model with the computational fluid dynamics software Fluent6.3. the characteristics of wind-sand flow structure around the roadbed are obtained. This paper explains the principle that sand particles cause wind erosion to the road matrix in the acceleration zone and form sand accumulation in the deceleration zone, and makes numerical simulation of the flow field around the roadbed model of desert highway after adding windproof sand retaining wall by using the standard k- 蔚 turbulence model. The sand movement track with different particle size, different friction velocity and different height of sand retaining wall is calculated by using discrete phase model. Based on this, the mechanism and performance of sand retaining wall wind and sediment suppression are analyzed and studied. It provides some reference and guidance for the practical design and construction of windproof sand retaining wall. The main content of this paper is divided into two parts. One is to simulate the flow field around the road roadbed model under different incoming wind speed. Secondly, the flow field around the road roadbed model under different initial wind speed and different height of windproof sand retaining wall is simulated and calculated. DPM (discrete phase model) was used to simulate the sand with different particle size. By calculation, the main conclusions are as follows: 1. In the flow field around the roadbed, relatively accelerated areas are formed at the top of the upwind slope and some areas above it, resulting in strong wind erosion to the roadbed, while relatively low speed zones are formed at the upper surface of the roadbed, at the foot of the leeward slope and at the foot of the upwind slope. Causes the sand grain kinetic energy to reduce, falls to the ground, forms the accumulation sand. 2. The flow field around the highway roadbed changed significantly after the sand retaining wall was set up. The conditions of judging the reasonable distance between windproof sand wall and highway roadbed are as follows: most sand particles in the airflow should be blocked by sand retaining wall on the upwind side of the roadbed, and there is no acceleration zone on the windward side of the roadbed, which will not cause strong wind erosion on the road shoulder. At the same time, it is necessary to make the wind and sand flow smoothly through the road subgrade surface. Through the DPM calculation of sand movement trajectory under different particle size, different friction wind speed and different height of windproof sand retaining wall, we can get the road roadbed model for this paper. When the height of windbreak sand retaining wall is 2 m and the sand retaining effect is 3 m from the base of highway roadbed, the best sand retaining effect is obtained. 3. Under the condition of different wind speed, the effect of windbreak sand retaining wall with certain height is different: when the wind speed is small, the effect of windbreak sand retaining wall is not obvious, and when the wind speed is larger, the roundabout area behind the wall is too large. When the wind speed is constant, with the height of the sand retaining wall increasing, the sand particles with higher entrance position can accelerate obviously, but have little effect on the flow field and sand movement at the bottom of the wall. In this way, we can conclude that in actual construction, the height of windproof sand retaining wall is slightly higher than the actual highway height, which is the most important factor, such as the effect of sand retaining wall and construction cost.
【学位授予单位】：兰州大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U418.56

【参考文献】