本文選題：沙漠公路 + 風(fēng)沙流��； 參考：《蘭州大學(xué)》2014年碩士論文

【摘要】：近年來,作為風(fēng)沙環(huán)境工程應(yīng)用的一個(gè)重大問題,戈壁地區(qū)沙漠公路風(fēng)蝕破壞問題受到越來越多的關(guān)注。本文通過計(jì)算流體動(dòng)力學(xué)軟件Fluent6.3,利用標(biāo)準(zhǔn)k-ε湍流模型對(duì)沙漠公路路基模型周圍的流場(chǎng)進(jìn)行了數(shù)值模擬計(jì)算,得出了路基周圍的風(fēng)沙流結(jié)構(gòu)特征,解釋了沙粒在加速區(qū)對(duì)路基體產(chǎn)生風(fēng)蝕,在減速區(qū)形成積沙的原理；利用標(biāo)準(zhǔn)k-ε湍流模型對(duì)加了防風(fēng)擋沙墻后的沙漠公路路基模型周圍流場(chǎng)進(jìn)行了數(shù)值模擬計(jì)算,并利用離散相模型計(jì)算了不同粒徑、不同摩阻風(fēng)速以及擋沙墻不同高度下的沙粒運(yùn)動(dòng)軌道,據(jù)此分析研究了擋沙墻擋風(fēng)抑沙的機(jī)理和性能,為實(shí)際設(shè)計(jì)和建設(shè)防風(fēng)擋沙墻提供了一些參考和指導(dǎo)。 本文的主要內(nèi)容分為兩部分,一是對(duì)不同來流風(fēng)速下的公路路基模型周圍流場(chǎng)進(jìn)行了模擬。二是對(duì)防風(fēng)擋沙墻與公路路基之間的不同距離、不同初始風(fēng)速和不同防風(fēng)擋沙墻高度下公路路基模型周圍的流場(chǎng)進(jìn)行了模擬計(jì)算,并對(duì)不同粒徑等三種情況下的沙粒進(jìn)行DPM(離散相模型)模擬。通過計(jì)算,主要結(jié)論為： 1.在公路路基周圍流場(chǎng)中,迎風(fēng)坡坡頂處及其上方部分區(qū)域內(nèi)形成相對(duì)加速區(qū),對(duì)路基產(chǎn)生強(qiáng)烈的風(fēng)蝕；而在路基上表面、背風(fēng)坡坡腳和迎風(fēng)坡坡腳位置處,形成相對(duì)低速區(qū),導(dǎo)致沙粒動(dòng)能減少,跌落到地面,形成積沙。 2.設(shè)置擋沙墻后公路路基周圍流場(chǎng)發(fā)生了顯著變化。防風(fēng)擋沙墻與公路路基合理距離的判斷條件為：氣流中大多沙粒應(yīng)該被擋沙墻擋在迎風(fēng)一側(cè)；在路基迎風(fēng)側(cè)不出現(xiàn)加速區(qū),不會(huì)對(duì)路肩產(chǎn)生強(qiáng)烈風(fēng)蝕,同時(shí)要使得風(fēng)沙流能平穩(wěn)通過公路路基表面。通過DPM計(jì)算了不同粒徑、不同摩阻風(fēng)速以及防風(fēng)擋沙墻不同高度下的沙粒運(yùn)動(dòng)軌跡,我們可以得到對(duì)于本文公路路基模型,防風(fēng)擋沙墻高度為2m,距離公路路基底部為3m時(shí)擋沙墻擋沙效果為最佳。 3.在不同的來流風(fēng)速條件下,高度一定的防風(fēng)擋沙墻效果是不同的：風(fēng)速較小時(shí),防風(fēng)擋沙的效果不明顯；風(fēng)速較大時(shí),墻后的回旋區(qū)過大。當(dāng)風(fēng)速一定時(shí),隨著擋沙墻高度增大,對(duì)入口處位置較高的沙粒有明顯的加速揚(yáng)起作用,但對(duì)墻后底部的流場(chǎng)及沙粒運(yùn)動(dòng)的影響不大。這樣我們可以得出：在實(shí)際建設(shè)中,綜合擋沙墻效果和建設(shè)成本等要素,防風(fēng)擋沙墻高度略高于實(shí)際公路高度為最
[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.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U418.56

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