本文選題：環(huán)境巖土工程 + 復(fù)合侵蝕�。� 參考：《內(nèi)蒙古工業(yè)大學(xué)》2014年碩士論文

【摘要】：內(nèi)蒙古自治區(qū)位于干旱寒冷的中國(guó)北方，因全年大風(fēng)日數(shù)、沙塵暴日數(shù)、積雪日數(shù)較多，加之常年平均氣溫較低、溫差變化較大，使得沙漠公路在風(fēng)沙、風(fēng)雪、風(fēng)雨等惡劣的自然環(huán)境下，不可避免地遭受著風(fēng)攜沙、風(fēng)吹雪、風(fēng)驅(qū)雨等復(fù)合侵蝕作用。 本文主要以沙漠風(fēng)沙土路基作為研究對(duì)象，以不設(shè)邊坡防護(hù)作為最不利情況進(jìn)行研究。通過(guò)風(fēng)攜沙粒子、風(fēng)吹雪粒子、風(fēng)驅(qū)雨滴粒子的風(fēng)洞高速攝影試驗(yàn)，研究風(fēng)攜帶下的不同粒子與路基邊坡撞擊瞬間的相互作用；研究路基斷面設(shè)計(jì)參數(shù)對(duì)粒子撞擊路基邊坡的位置、撞擊瞬間的角度和速度的影響。對(duì)于同種粒子，當(dāng)風(fēng)速一定，路基填料含水率一定時(shí)，路基模型為矮路基，邊坡坡率越緩，則大粒子大部分撞擊在坡中上部后回彈并繼續(xù)從路基頂面越過(guò)，而小粒子大部分越過(guò)路基頂面；路基模型為高路基，，邊坡坡率越緩，大粒子大部分撞擊在路基邊坡經(jīng)多次向上反彈后能量逐漸損失，沿坡面下滑或粒子反彈后直接飛向路基坡腳處堆積，而小粒子大部分附著在坡面上。對(duì)于同種粒子，路基模型的各種參數(shù)相同時(shí)，路基填料含水率增大，導(dǎo)致沙粒子和雪粒子附著在路基坡面的粒子增多，雨滴粒子滲入路基減少，很快形成沖刷路基現(xiàn)象。 通過(guò)改變路基中心線與來(lái)風(fēng)向的夾角，利用風(fēng)洞高速攝影試驗(yàn)，對(duì)不同夾角下各種粒子運(yùn)動(dòng)軌跡進(jìn)行研究。路基模型的各種參數(shù)相同時(shí)，當(dāng)路基中心線與來(lái)風(fēng)向的交角變小時(shí)，在路基坡面處形成的渦流小，路基填料被風(fēng)卷走的也就減少了，沙粒子打擊在坡肩回彈后越過(guò)路基，或者粒子堆積坡腳處減少，對(duì)路基的風(fēng)蝕侵害變小。雪粒子附著在坡面上增多，考慮溫度的變化則會(huì)對(duì)路基造成因積雪融化滲入路基內(nèi)部而引發(fā)凍融循環(huán)破壞，或融水坡面徑流侵蝕破壞，而風(fēng)驅(qū)雨滴粒子打在坡腳處的雨滴減少，對(duì)路基的雨滴鑿蝕破壞減小。 以風(fēng)吹雪粒子可能引發(fā)的凍融風(fēng)蝕復(fù)合侵蝕為例，通過(guò)體視顯微鏡進(jìn)行微觀掃描，研究路基在凍融風(fēng)蝕復(fù)合侵蝕作用下對(duì)路基的破壞機(jī)理。利用Micrograph圖片分析軟件提取路基土凍融風(fēng)蝕前后微觀孔隙結(jié)構(gòu)參數(shù)，分析凍融循環(huán)次數(shù)、路基土含水率、風(fēng)蝕作用對(duì)路基各試驗(yàn)層孔隙面積的影響。當(dāng)路基填料含水率一定，隨著凍融次數(shù)的增加，對(duì)路基坡面表層侵蝕破壞越大，隨著水平測(cè)試深度增加，由坡面向內(nèi)部侵蝕作用減小。凍融后繼續(xù)進(jìn)行吹蝕路基，路基在復(fù)合侵蝕作用下，坡面的破壞更為嚴(yán)重，尤其對(duì)路基坡肩的影響最為嚴(yán)重。
[Abstract]:The Inner Mongolia Autonomous region is located in the arid and cold north of China. Due to the number of windy days, the days of sandstorms and the number of snow days throughout the year, coupled with the relatively low annual average temperature and the large variation of temperature differences, the desert roads are windy, sandy and snowy. Under the adverse natural environment such as wind and rain, it is inevitable to be subjected to the combined erosion of wind and sand, wind and snow, wind and rain, etc. In this paper, the sand and sand subgrade in the desert is taken as the research object and the slope protection is the most unfavorable condition. Through the wind tunnel high-speed photography test of wind sand carrying particles, wind snow particles, wind dripping raindrops particles, the interaction between different particles carried by wind and embankment slope impact moment was studied. The influence of design parameters of roadbed section on the position, angle and velocity of particle impact on embankment slope is studied. For the same kind of particles, when the wind speed is constant and the moisture content of the subgrade filler is constant, the roadbed model is low subgrade, and the slope ratio of the side slope is slower, then most of the particles will bounce back in the middle and upper part of the slope and continue to cross from the top of the roadbed. However, most of the small particles cross the top surface of the roadbed, the roadbed model is high subgrade, the slope ratio of the side slope is slower, the energy of the subgrade slope is gradually lost after most of the particles impact on the embankment slope after several times bouncing upward. After falling or bouncing along the slope, the particles will pile up directly to the foot of the embankment slope, while most of the small particles will adhere to the slope. For the same particle, when the parameters of the subgrade model are the same, the moisture content of the subgrade filler increases, resulting in the increase of the particles of sand and snow particles attached to the embankment slope, and the decrease of the infiltration of raindrops into the roadbed. By changing the angle between the center line of the roadbed and the direction of the wind, and using the high-speed photography test of the wind tunnel, the motion trajectories of various particles at different angles are studied. When the parameters of the roadbed model are the same, when the angle between the center line of the subgrade and the direction of the wind changes, the eddy current formed at the slope of the roadbed is small, and the filling of the roadbed is reduced by the wind, and the sand particles strike the embankment and bounce back over the roadbed after the shoulder of the slope. Or particle accumulation at the foot of the slope to reduce the roadbed wind erosion damage becomes smaller. When snow particles are attached to the slope surface, considering the change of temperature, the subgrade will be damaged by freeze-thaw cycle due to the melting of snow and infiltration into the subgrade, or runoff erosion damage will be caused by the melting water sloping surface, while the raindrop droplets driven by wind will decrease at the foot of the slope. Taking the wind-thawing composite erosion caused by wind-blown snow particles as an example, the failure mechanism of roadbed under the combined erosion of freeze-thaw wind erosion is studied by microscopic scanning of stereomicroscope. The micro-pore structure parameters of roadbed soil before and after freeze-thaw wind erosion were extracted by Micrograph image analysis software. The effects of freeze-thaw cycle times, soil moisture content and wind erosion on the pore area of each test layer of roadbed were analyzed. With the increase of freezing and thawing times, the surface erosion damage of embankment slope is greater, and with the increase of horizontal testing depth, the erosion effect from slope to interior decreases with the constant moisture content of subgrade filler. After freezing and thawing, the roadbed continues to be blown away, and the damage of the slope surface is more serious, especially on the shoulder of the embankment under the action of composite erosion.
【學(xué)位授予單位】：內(nèi)蒙古工業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：U416.1

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本文編號(hào)：2003195