發(fā)布時間：2018-01-17 15:32

  本文關鍵詞：三峽庫區(qū)低等級土質道路侵蝕及防護研究　出處：《華中農業(yè)大學》2014年博士論文　論文類型：學位論文

  更多相關文章： 道路侵蝕 三峽庫區(qū) 道路邊坡防護 水文過程 路面初始沖刷

【摘要】：道路網(wǎng)絡建設和發(fā)展是區(qū)域經(jīng)濟發(fā)展的基礎和保障,是促進不同區(qū)域之間能流、物流、信息流交換的重要通道。然而道路作為一種純粹的人為景觀,必然對周邊生態(tài)環(huán)境產(chǎn)生影響。在三峽庫區(qū),地形起伏大,人為建設活動頻繁,道路建設與維修活動所形成的土壤侵蝕已經(jīng)成為不可忽視的土壤流失類型,影響流域水文過程、受納水體水質,加速庫區(qū)淤積,成為一個亟待解決的環(huán)境問題。開展道路,尤其是低等級土質道路的侵蝕規(guī)律及防護的研究,弄清道路侵蝕-水文過程及其防控途徑,對于完善區(qū)域-坡面土壤侵蝕過程研究有重要理論意義,對解決三峽庫區(qū)道路侵蝕防護有重要的實踐意義。本文以土質道路為研究對象,將道路系統(tǒng)分解為路塹邊坡、路面和路堤邊坡,通過設置不同邊坡植被防護模式如自然恢復(NR)、草灌結合(GS)、草本(GR)、梯坎＆草灌結合(TGS)、植生帶(SS)、坡耕地(FL)、草本坡耕地(GF),結合人工模擬降雨試驗、模擬沖刷試驗、原位剪切試驗等,分析不同植被防護模式對道路路塹和路堤邊坡土壤性質改良、強度提升、侵蝕規(guī)律和防護等方面影響,遴選出最佳防護模式。通過室內模擬降雨試驗,研究不同路面結構降雨產(chǎn)流產(chǎn)沙規(guī)律及邊溝對路面侵蝕水沙輸移影響,借助臨時路面徑流小區(qū),通過野外自然降雨觀測試驗,探討不同交通荷載和雨型等條件下,路面侵蝕及污染物初始沖刷等相關問題。主要研究結果如下：(1)通過在道路邊坡進行植物防護和原位剪切試驗,研究了不同植被防護措施對邊坡抗剪強度(.τ)影響。結果表明,植被根系隨土壤深度增加而減少,表層(0-10 cm)根系長度密度(Root length density, RLD)占總RLD的34%-78%；植被根系含量及蓋度與土壤水分含量(Soil water content, SWC)呈指數(shù)正相關。表層(0-10 cm)土壤抗剪強度主要受植被根系及蓋度影響,隨著根系長度密度(RLD)、根系重量密度(Root weight density, RWD)、植被蓋度(Vegetation cover,VC)增加呈指數(shù)形式增大。30 cmm深度土壤抗剪強度值顯著低于10 cm值和50 cm值。隨著土壤深度增加,土壤容重和水分對抗剪強度影響力增大,在50 cm處兩者分別與抗剪強度呈線性正相關和指數(shù)負相關關系。(2)邊坡植被在經(jīng)過8個月自然生長之后,選擇路塹和路堤30。邊坡小區(qū)作為模擬降雨對象。試驗結果表明：路塹邊坡侵蝕量高于路堤邊坡侵蝕量。草灌結合措施,由于致密的地表覆蓋(蓋度91.4%,地上生物量1.44kgm-2)和發(fā)育良好的地下根系系統(tǒng)(RWD3.94 kgm-3),徑流系數(shù)(4.3%)和土壤侵蝕率(1.99 g m-2 min-1)顯著低于其它防護措施。雖然植生帶措施和草本措施選擇相同的品種,但是由于植生帶措施尚未完全發(fā)育的地下根系(RWD1.50kgm-3, RLD2.11 kmm-3),土壤侵蝕量(38.5 gm-2 min-1)顯著高于草本措施。土壤侵蝕量、徑流系數(shù)等隨植被根系含量、地表生物量增加而呈對線下降。模擬降雨前后,草灌結合措施土壤抗剪切強度最高(分別為59.29 kPa和53.73 kPa),其次為草本措施(46.93 kPa和40.48 kPa)和植生帶措施(31.20 kPa和18.87 kPa),自然恢復小區(qū)最低為25.31 kPa和9.36 kPa。而抗剪強度衰退值相反,自然恢復措施衰退值最高為15.95 kPa,草灌結合最低為5.56 kPa。土壤抗剪強度衰退值與植被根系及地上生物量呈極顯著線性負相關。降雨過程中,抗剪強度的變化與侵蝕過程密切相關,抗剪強度衰退值與徑流系數(shù)呈線性正增長關系與土壤侵蝕率呈冪函數(shù)增長關系。(3)通過模擬降雨(雨強90 mm h-1和120mm h-1)與模擬沖刷(放水量15 L min-1和20 L min-1)試驗相結合的方式,研究降雨與路面匯水對路堤邊坡侵蝕影響。在模擬降雨試驗下,草灌結合產(chǎn)流和產(chǎn)沙量最低,截流和攔沙效率顯著高于其它防護模式。模擬沖刷試驗下,各措施的水文響應要明顯比模擬降雨試驗下更迅速,初始產(chǎn)流時間更快。相同措施下,模擬沖刷試驗下侵蝕量要高于模擬降雨。水穩(wěn)性團聚體含量、飽和導水率、植被蓋度和根系含量在降雨和沖刷試驗下均顯著影響路堤邊坡的土壤侵蝕量。模擬沖刷試驗下,草本措施致密的地下根系地面根莖增加入滲量,分散和消弱徑流侵蝕力,并提供額外的地表粗糙度,截流攔沙能力高于草灌結合措施,在路堤邊坡有集中水流影響下,防護效果最佳。(4)通過模擬降雨試驗,研究拱型、側傾型、平直型和凹型等路形路面侵蝕特征。試驗結果顯示：路形對侵蝕特征有顯著影響,平直型和凹型路面降雨產(chǎn)流量和產(chǎn)流率高于拱型和側傾型。凹型土壤侵蝕率最高是拱型路面侵蝕率的11～14倍。路形通過改變路面降雨徑流水動力學參數(shù)來影響侵蝕過程。徑流流速、雷諾數(shù)和弗洛德數(shù)隨拱型側向型平直型凹型迅速增加,而徑流深、Darcy-Weisbach阻力系數(shù)和曼寧ae率隨拱型側向型平直型凹型依次降低。不同路形條件下,邊溝改變路面侵蝕水沙輸移特征。拱型路面67%-82%的徑流和85%-94%的泥沙是通過兩側邊溝輸出的,路面輸出量比例低；凹型路面90%以上的水沙均通過路面進行輸出的,邊溝徑流輸出量僅為3%～5%,泥沙輸出量為4%-7%。(5)通過自然降雨觀測研究不同交通荷載及雨型條件下路面侵蝕規(guī)律和污染物流失特征。研究結果表明,交通荷載大的干道產(chǎn)流率和侵蝕率均高于交通荷載低的支道,對產(chǎn)流率影響顯著的因子主要為降雨量,對產(chǎn)沙率影響顯著的因子為降雨量、雨強。雨型對污染物的流失特征影響顯著,不同雨型下,污染物的濃度峰值和雨強峰值表現(xiàn)出不同的滯后性,氮素的流失以總氮為主,磷素流失則以泥沙結合態(tài)為主。雨型影響污染物的初始沖刷特征,泥沙的初始沖刷強度較弱,而總氮、銨態(tài)氮、泥沙結合態(tài)磷和溶解態(tài)磷均發(fā)生了強度較大的初始沖刷效應。本試驗結果雖然僅來自于三峽庫區(qū)較小研究區(qū)域內,但是相關試驗結果能適用于國內外其它相似環(huán)境。對類似低等級土質道路的設計、施工及管理提供必要的理論解釋。試驗結果中有一些還待進一步的研究(如土質道路初始沖刷定義等),便于更好的服務于流域侵蝕管理和水文水質安全。
[Abstract]:The road network construction and development is the foundation and guarantee of regional economic development, is to promote inter regional flow, logistics, information flow exchange important channel. However, the road as a purely man-made landscape, the inevitable impact on the surrounding ecological environment. In the Three Gorges Reservoir area, terrain fluctuation, human construction activities, soil erosion formed by road construction and maintenance activities have become the noticeable loss of soil types, influence the hydrological process, the water quality of receiving water, accelerate the reservoir, become an urgent environmental problem. The development of the road, especially the study of erosion and protection of low grade unpaved roads, clear road erosion the hydrological process and its prevention and control, to improve the region has important theoretical significance for studying soil erosion process of slope, to solve the road erosion in Three Gorges Reservoir area has important practical significance for the protection. The road to the soil as the research object, the system is divided into road slope and road embankment slope, by setting different slope vegetation protection modes such as natural recovery (NR), (GS), combination of grass and shrub herb (GR), terrace & grass shrub combination (TGS), vegetation (SS) (FL), slope farmland, farmland herb (GF), combined with the artificial rainfall simulation experiment, simulation of scouring, in-situ shear test, analysis of the protection mode of different vegetation on road cut slope and embankment slope soil properties improvement, increase strength, erosion and protection and other aspects, select the best protection pattern through. Indoor rainfall simulation experiment of different pavement runoff law and ditch erosion of water and sediment transportation on the road, with the runoff of temporary pavement, through field observation experiment on natural rainfall, different traffic loads and rain conditions, surface erosion and pollutants The initial problems related to erosion. The main results are as follows: (1) through the door and in situ shear test plants in road slope, the protective measures of different vegetation on the shear strength of the slope (. T) effect. The results showed that the vegetation roots decreased with increasing soil depth, the surface (0-10 cm) root length density (Root length density, RLD) the total RLD of 34%-78%; the content and coverage of vegetation roots and soil moisture content (Soil water, content, SWC) were positively correlated (0-10 cm). The surface strength is mainly affected by the vegetation cover of the root and influence of soil shear, with root length density (RLD), root weight density (Root weight density, RWD), vegetation coverage (Vegetation cover, VC) increased exponentially with the increase of.30 CMM depth of soil shear strength was significantly lower than that of 10 cm and 50 cm value. With the increase of soil depth, soil bulk density and moisture content on the shear strength. The force increases at 50 cm respectively and the shear strength index showed a linear positive correlation and negative correlation. (2) slope vegetation after 8 months of natural growth, choose to cut and fill 30. slope area as rainfall simulation object. The experimental results show that the slope erosion is higher than that of embankment slope erosion the grass. Combining irrigation measures, due to the dense surface coverage (coverage 91.4%, ground biomass 1.44kgm-2) and well-developed root system (RWD3.94 kgm-3) (4.3%), runoff coefficient and soil erosion rate (1.99 g m-2 min-1) was significantly lower than that of the protective measures. Although the vegetation measures and herb selection measures the same species, but due to the underground root vegetation measures are not yet fully developed (RWD1.50kgm-3, RLD2.11, kmm-3), the amount of soil erosion (38.5 GM-2 min-1) was significantly higher than that of herbaceous measures. The amount of soil erosion, runoff coefficient with vegetation root The content of above ground biomass increased on line drop. The simulated rainfall after grass irrigation combined with measures of soil anti shearing strength is the highest (59.29 kPa and 53.73 kPa), followed by herbal measures (46.93 kPa and 40.48 kPa) and vegetation measures (31.20 kPa and 18.87 kPa), the natural restoration area minimum 25.31 kPa and 9.36 kPa., while the shear strength value decline instead, natural restoration measures decline value of up to 15.95 kPa, with a minimum of 5.56 kPa. of shrub and grass soil shear strength decline were significantly linear and vegetation root and aboveground biomass negatively. During rainfall process, closely related to changes in shear strength with the erosion process, the shear strength of the recession were linear positive relationship with the growth rate of soil erosion in a power function relationship with the runoff coefficient of growth. (3) by simulated rainfall (rainfall intensity of 90 mm H-1 and 120mm h-1) and simulation (15 L min-1 scouring water discharge and 20 L min-1) test. Combination effects of rainfall and road embankment slope erosion in the catchment. The simulated rainfall experiment, combining irrigation grass runoff and sediment yield was the lowest, and the closure of sediment efficiency was significantly higher than that of other protective mode. Simulation washout test, the response to hydrological measures than simulated rainfall experiment more quickly the initial runoff time faster. The same measures under the simulated scouring experiment under simulated rainfall. Soil erosion amount is higher than the content of water stable aggregates, saturated hydraulic conductivity, vegetation coverage and root content in rainfall and erosion tests have significant influences on erosion of embankment slope soil erosion experiment. Simulation under ground rhizome herb roots dense measures to increase the amount of infiltration, runoff erosivity dispersion and extinction, and provide additional surface roughness, sediment interception capacity is higher than that of shrub and grass combined measures have concentrated flow effect in embankment slope under the protective effect The best result. (4) through the rainfall simulation experiment, research of arch type, roll type, flat type and concave shaped road pavement erosion characteristics. Experimental results show that the road shape has a significant influence on the soil erosion characteristics, flat and concave road rainfall runoff and runoff rate is higher than the arch and roll type concave. The soil erosion rate is the highest arch pavement erosion rate of 11 ~ 14 times. The road shape by changing the surface runoff kinetic parameters to influence the erosion process. Runoff velocity, Reynolds number and Flood number increases rapidly with the lateral arch type flat type concave type, and runoff depth, the drag coefficient Darcy-Weisbach and Manning AE rate with arch lateral type flat type concave shape decreased. Different road conditions, side ditch erosion change water and sediment transport characteristics of road pavement. Arch 67%-82% and 85%-94% runoff sediment is through the two side channel output, the proportion of pavement output is low; the concave surface 90% Above the water through sand road side ditch runoff output, output is only 3% ~ 5%, the sediment output was 4%-7%. (5) through the observation and study of natural rainfall in different road traffic load and under the condition of rain erosion rules and pollution characteristics. The results show that the traffic load of the road runoff rate and the erosion rate was higher than that of road traffic load is low, significantly influencing factors of runoff rate is mainly on rainfall, sediment yield significantly influence factor of rainfall, rainfall intensity. The loss characteristics of rain type of pollutants significantly affect the different types of rain, the pollutant concentration peak and peak showed different rain intensity the lag, the loss of nitrogen to total nitrogen and phosphorus loss in sediment bound pollutants. The initial scour characteristics of rain type, initial sediment erosion intensity is weak, while the total nitrogen, ammonium nitrogen, phosphorus and dissolved with sediment P had the first flush effect of greater strength. The result although only from the Three Gorges Reservoir area is smaller in the study area, but the test results can be applied to other domestic and foreign environment. Similar to the design of similar low levels of unpaved roads, construction and management to provide the necessary theoretical explanation. The experimental results in some further the research (such as soil erosion, such as the definition of the initial road) to better serve the watershed erosion management and hydrology and water quality safety.

【學位授予單位】：華中農業(yè)大學
【學位級別】：博士
【學位授予年份】：2014
【分類號】：U418;S157

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