本文選題：董志塬 + 溝頭��； 參考：《西北農(nóng)林科技大學》2017年碩士論文

【摘要】：董志塬塬面廣闊平坦,具有極其寶貴的土地資源及農(nóng)業(yè)生產(chǎn)條件。然而長期嚴重的溝頭溯源侵蝕,使塬面面積不斷蠶食萎縮,甚至面臨損失殆盡的威脅,已成為當?shù)厣鷳B(tài)建設與經(jīng)濟社會可持續(xù)發(fā)展的嚴重隱患。開展董志塬溝頭溯源侵蝕過程及水力學特征研究可以深入揭示溯源侵蝕過程機理,深刻認識塬面侵蝕萎縮演變及塬區(qū)強烈侵蝕產(chǎn)沙規(guī)律,促進溝蝕過程研究進一步發(fā)展,為溝蝕過程模型研究奠定重要基礎,并為控制董志塬等黃土塬區(qū)溝頭溯源侵蝕,阻滯塬面侵蝕萎縮及塬區(qū)侵蝕產(chǎn)沙,實現(xiàn)董志塬等黃土塬區(qū)土地資源有效管理及水土流失科學治理提供重要科學依據(jù)。本論文在概化修建的黃土塬塬面模型及溝頭模型小區(qū)(投影面積皆為5.0×1.5 m~2)上,采用野外定雨強模擬降雨+放水沖刷試驗方法,對2個塬面坡度(3°和6°),2個溝坡高度(0 m和1.5 m,溝坡坡度90°),1個固定雨強(2.0 mm/min),4個放水流量(100L/min、200 L/min、300 L/min、400 L/min),各流量連續(xù)4場次放水試驗條件下的董志塬溝頭溯源侵蝕過程及水力學特征進行了研究,分析研究了董志塬土壤物理性質(zhì)、溝頭溯源侵蝕過程、溝頭溯源侵蝕水流水力學特征及溝頭溯源侵蝕過程動力學機理。主要研究結(jié)果如下:(1)不同深度(0~150 cm)土壤容重介于1.23~1.30 g/cm~3之間,平均值為1.26 g/cm3,隨土壤深度增加,土壤容重加大;不同深度土壤含水量為10.54%~13.18%,平均值為11.77%,隨土壤深度增加,土壤含水量呈先增加后減小的變化;土壤粘聚力和內(nèi)摩擦角分別為14.92 kPa和13.22°,二者均隨土壤含水量增加而減小,土壤含水量達到10%、15%和20%時,粘聚力較含水量為6.31%時(16.39 kPa)分別減小3.05%、6.83%和26.11%,內(nèi)摩擦角較含水量為6.31%時(15°)分別減小3.58%、13.48%和40.06%;以土壤剖面0~10 cm為基準(0.29 g/min),10~20 cm、20~50 cm、50~90 cm和90~150 cm土層的土壤崩解速率分別增大253.42%、222.28%、380.40%和481.81%,土層越深,土壤崩解速率越快。(2)在放水流量為100~400 L/min,溝坡高度0 m時,塬面坡度3°小區(qū)的平均徑流率分別為103.71 L/min、270.24 L/min、386.64 L/min、528.46 L/min,平均徑流率與放水流量間呈極顯著線性相關(guān),6°小區(qū)的平均徑流率分別為133.10 L/min、154.77 L/min、273.24 L/min和273.11 L/min,平均徑流率與放水流量間呈指數(shù)相關(guān)。溝坡高度為1.5 m時,3°小區(qū)平均徑流率分別為164.84 L/min、198.27 L/min、211.31 L/min、200.98 L/min,平均徑流率與放水流量間呈冪函數(shù)相關(guān),6°小區(qū)的平均徑流率分別為60.12 L/min、122.23L/min、153.07 L/min和240.52 L/min,平均徑流率與放水流量間呈極顯著線性相關(guān)。塬面坡度為3°及6°時,溝坡高度1.5m的平均徑流率是0m的158.94%、73.37%、54.65%、38.03%及45.17%、78.98%、56.02%、88.07%;溝坡高度為0m時,塬面坡度3°和6°小區(qū)在4個放水流量下的平均產(chǎn)流徑流量分別為6222.65l、16214.4l、23198.11l、31707.77l和7986.01l、9286.34l、16394.63l、13182.1l,溝坡高度為1.5m時,對應值分別為9890.58l,11896.38l,12678.8l、12058.73l和3541.14l、7333.53l、9184.10l、13392.54l,溝坡高度為0m時,塬面坡度3°和6°下的平均徑流量與放水流量間分別呈線性和冪函數(shù)相關(guān),溝坡高度為1.5m時,分別呈冪函數(shù)和線性相關(guān),塬面坡度為3°及6°時,溝坡高度1.5m的平均徑流量是0m的158.94%、73.37%、54.65%、38.03%和45.17%、78.98%、56.02%和88.07%。(3)溝坡高度為0m和1.5m時,隨放水流量增大,塬面坡度3°小區(qū)在放水流量100l/min、200l/min、300l/min、400l/min下的平均產(chǎn)沙量分別為99.98kg、368.95kg、586.70kg、806.06kg和353.65kg、463.88kg、654.52kg、849.94kg,產(chǎn)沙量與放水流量間均呈極顯著線性相關(guān),產(chǎn)沙量隨溝坡高度增加而增加,4個放水流量下,溝坡高度1.5m的產(chǎn)沙量是0m的3.54、1.26、1.12和1.05倍,隨溝坡高度增加,溝壁形成拋物線型性侵蝕,產(chǎn)沙量也隨之增大;相同條件下,平均含沙量分別為16.88g/l、26.97g/l、29.01g/l、31.60g/l和46.99g/l、65.55g/l、46.12g/l、30.37g/l,溝坡高度為0m時含沙量與放水流量間呈顯著的對數(shù)函數(shù)關(guān)系,1.5m時呈拋物線相關(guān),隨放水流量增加,溝坡高度對含沙量的影響減緩,4個放水流量下,溝坡高度1.5m的含沙量是0m的2.78、2.43、1.59和0.96倍;試驗條件下侵蝕產(chǎn)沙的粘粒、粉粒和砂粒含量平均值為23.02%、68.36%和8.62%,砂粒含量均隨放水流量增加而減小,塬面坡度-溝坡高度為3°-0m下粘粒含量隨放水流量增加先增后減,粉粒含量先減后增,3°-1.5m下粘粒含量隨放水流量增加先減后增,粉粒含量先增后減。(4)放水流量100l/min、200l/min、300l/min、400l/min下,溝坡高度為1.5m,塬面坡度3°和6°小區(qū)的平均流速分別為0.75m/s、0.85m/s、0.95m/s、0.99m/s和0.85m/s、1.15m/s、1.06m/s、1.05m/s,塬面坡度為3°時,平均流速與放水流量間呈顯著線性相關(guān),而塬面坡度為6°,放水流量在100、200l/min時,平均流速隨放水流量的增大而加大,隨放水流量繼續(xù)增加,坡面流速略有下降,但仍大于放水流量為100l/min時的流速。試驗條件下雷諾數(shù)均大于500,屬于紊流流態(tài),弗汝德數(shù)均大于1,水流為急流。溝坡高度為1.5m時,塬面坡度3°和6°小區(qū)的平均徑流剪切力分別為1.71n/m~2、1.92n/m~2、2.75n/m~2和1.95n/m~2、2.71n/m~2、2.76n/m~2、1.37n/m~2,2種坡度下,剪切力與放水流量間分別呈線性函數(shù)和對數(shù)函數(shù)相關(guān);溝坡高度為1.5m時,塬面坡度3°和6°小區(qū)的平均徑流功率分別為1.27w/m~2、1.63w/m~2、2.61w/m~2、2.84w/m~2和1.05w/m~2、1.19w/m~2、1.56w/m~2、1.56w/m~2,塬面坡度3°小區(qū)徑流功率與放水流量間呈極顯著線性相關(guān),6°小區(qū)在放水流量為100~300l/min時,徑流功率與放水流量間呈對數(shù)函數(shù)相關(guān),但放水流量400l/min時,徑流功率有所下降;溝坡高度為1.5m時,塬面坡度3°和6°小區(qū)的單位徑流功率分別為0.039 m/s、0.045 m/s、0.050 m/s、0.052 m/s和0.039 m/s、0.047 m/s、0.052 m/s、0.055 m/s,單位徑流功率與放水流量間均呈對數(shù)函數(shù)相關(guān);次侵蝕產(chǎn)沙量與徑流功率間的關(guān)系在2種溝坡高度下均為最好,流速和單位徑流功率次之,徑流剪切力最差,徑流功率是與試驗條件下溝頭溯源侵蝕產(chǎn)沙關(guān)系最好的水動力學參數(shù)和動力根源。
[Abstract]:Dongzhi tableland has a vast flat surface, and has extremely valuable land resources and agricultural production conditions. However, long and serious gully head retrogressive erosion has made the tableland area continuously shrunk, even faced with the threat of loss, which has become a serious hidden danger to the local ecological construction and the sustainable development of the economy and society. The study of process and hydraulic characteristics can deeply reveal the mechanism of the process of traceability erosion, deeply understand the evolution of the erosion and evolution of the tableland erosion and the law of strong erosion and sediment yield in the tableland, promote the further development of the furrow erosion process, and lay an important foundation for the study of the ditch erosion process model, and control the source erosion of the gully head in the Loess Tableland and other loess tableland areas of Dong Zhi Tableland and block the surface invasion of the tableland. An important scientific basis for effective management of land resources and the scientific management of soil erosion in the loess tableland area of Dongzhi tableland is provided by erosion and erosion and erosion and sediment yield. In this paper, the model of the Loess Tableland of the tableland of the Loess Tableland and the area of the gully head model are 5 * 1.5 m~2 of the projection area, and the field rainfall intensity simulated rainfall + water discharge scour test is used. In the method, 2 slope gradients (3 and 6 degrees), 2 gully slope height (0 m and 1.5 m, groove slope degree 90), 1 fixed rain intensity (2 mm/min), 4 discharge flow (100L/min, 200 L/min, 300 L/min, 400 L/min), the erosion process and hydraulics characteristics of the Dong Zhi gully head under the condition of continuous discharge experiments were studied. The physical properties of the soil in the tableland, the erosion process of gully head traceability, the hydrodynamic characteristics of the water flow and the dynamic mechanism of the erosion process in the gully head are the main results as follows: (1) the soil bulk density at different depths (0~150 cm) is between 1.23~1.30 g/cm~3, the average value is 1.26 g/cm3, and the soil bulk density increases with the depth of soil, and the soil bulk density increases; the soil bulk density increases with the depth of the soil; The soil moisture content is 10.54%~13.18%, the average value is 11.77%, with the increase of soil depth, the soil moisture content increases first and then decreases, the cohesive force and the internal friction angle of soil are 14.92 kPa and 13.22 degrees respectively. The two people all decrease with the increase of soil water content, and the soil water content reaches 10%, 15% and 20%, the cohesive force is 6.31% when the water content is 16.39 K Pa) decreased by 3.05%, 6.83% and 26.11% respectively, and the internal friction angle was 3.58%, 13.48% and 40.06% when the water content was 6.31% (15 degrees), respectively, with the soil profile 0~10 cm (0.29 g/min), 10~20 cm, 20~50 cm, 50~90 cm and 90~150 cm soil increased 253.42%, 222.28%, 380.40% and 481.81%, the deeper the soil layer, the soil disintegration rate. The quicker. (2) when the discharge flow rate is 100~400 L/min and the slope height is 0 m, the average diameter flow rate of the 3 degree plot is 103.71 L/min, 270.24 L/min, 386.64 L/min, 528.46 L/min, respectively. The average diameter flow rate is significantly linear with the discharge flow rate, and the average diameter of the 6 degree plot is 133.10 L/min, 154.77 L/min, 273.24 L/min and 273, respectively. .11 L/min, the average diameter flow rate is exponentially related to the discharge flow rate. When the height of the ditch is 1.5 m, the average diameter of 3 degrees is 164.84 L/min, 198.27 L/min, 211.31 L/min, 200.98 L/min. The average diameter flow rate is related to the power function of the discharge flow, and the average diameter of the 6 degree plot is 60.12 L/min, 122.23L/min, 153.07 L/min and 240., respectively. 52 L/min, the average runoff rate has a very significant linear correlation with the discharge flow rate. When the plateau slope is 3 and 6 degrees, the average diameter of 1.5m is 158.94%, 73.37%, 54.65%, 38.03% and 45.17%, 78.98%, 56.02%, 88.07%, when the slope height is 0m, and the average runoff runoff of the slope 3 degree and 6 degree area under the flood discharge are respectively at 0m. When 6222.65l, 16214.4l, 23198.11l, 31707.77l and 7986.01l, 9286.34l, 16394.63l, 13182.1l, the height of the ditch slope is 1.5m, the corresponding values are 9890.58l and 12678.8l. Function correlation, when the slope height is 1.5m, it is power function and linear correlation. When the slope of the plateau is 3 and 6 degrees, the average runoff of 1.5m is 158.94%, 73.37%, 54.65%, 38.03% and 45.17%, 78.98%, 56.02% and 88.07%. (3) is 0m and 1.5m, which increases with the discharge flow, and the slope of the tableland is 3 degrees in the discharge flow 100l/min, The average sediment yield under 200l/min, 300l/min and 400l/min is 99.98kg, 368.95kg, 586.70kg, 806.06kg and 353.65kg, 463.88kg, 654.52kg, 849.94kg. The sediment yield is significantly linearly correlated with the discharge flow, and the sediment yield increases with the increase of the slope height. Under the 4 discharge flow, the sediment yield of the ditch height 1.5m is 1. In the same condition, the average sediment content is 16.88g/l, 26.97g/l, 29.01g/l, 31.60g/l and 46.99g/l, 65.55g/l, 46.12g/l, 30.37g/l, and there is a significant logarithmic function relationship between the sediment content and the discharge flow when the height of the ditch is 0m, and the 1.5m is parabola when 1.5m is in the same condition. Correlation, with the increase of discharge flow, the effect of slope height on sediment content is slowed down. Under 4 discharge flows, the sediment concentration of 1.5m in the slope height is 2.78,2.43,1.59 and 0.96 times of that of 0m. The average value of the clay grain and sand grain content under the test conditions is 23.02%, 68.36% and 8.62%, and the sand grain content decreases with the increase of the discharge flow rate and the plateau slope. The content of clay particles increased first and then decreased with the increase of the discharge flow rate under the degree of 3 degree -0m. The content of the particles decreased first and then increased with the increase of the discharge flow rate. The content of the particles increased first and then decreased. (4) the discharge flow rate was 100l/min, 200l/min, 300l/min and 400l/min, the slope height was 1.5m, the average velocity of the slope of the tableland and the average velocity of 3 and 6 degrees was 3. When 0.75m/s, 0.85m/s, 0.95m/s, 0.99m/s and 0.85m/s, 1.15m/s, 1.06m/s, 1.05m/s, the slope of the tableland is 3 degrees, the average flow velocity is linearly correlated with the discharge flow, while the slope of the tableland is 6 degrees. When the discharge flow is at 100200l/min, the average flow velocity increases with the increase of the discharge flow, and the flow rate continues to increase and the slope velocity is slightly lower. The flow rate is still larger than the flow rate of 100l/min. The Reynolds number is more than 500 under the test condition, which belongs to the turbulent flow, the Froude number is more than 1, the flow is a jet stream. When the slope height is 1.5m, the average runoff shear force of the 3 and 6 degrees area of the tableland is 1.71n/m~2,1.92n /m~2,2.75n/m~2 and 1.95n/m~2,2.71n/m~2,2.76n/m~2,1.37n/m, respectively. Under the ~2,2 gradient, the shear force and the discharge flow are linear and logarithmic function respectively. When the slope height is 1.5m, the average runoff power of the 3 and 6 degree plots of the tableland is 1.27w/m~2,1.63w/m~2,2.61w/m~2,2.84w/m~2 and 1.05w/m~2,1.19w/m~2,1.56w/m~2,1.56w/m~2 respectively. The runoff power and the discharge flow rate of the plot slope of the tableland are 3 degrees. There is a very significant linear correlation between the flow power and the discharge flow rate of 100~300l/min in the 6 degree area. But the runoff power is logarithmic function, but when the discharge flow is 400l/min, the runoff power is reduced. When the slope height is 1.5m, the unit runoff power of the 3 and 6 degree plots of the tableland is 0.039 m/s, 0.045 m/s, 0.050 m/s, 0.052 m/s and 0., respectively. 039 m/s, 0.047 m/s, 0.052 m/s, 0.055 m/s, both unit runoff power and discharge flow are logarithmic function correlation, and the relationship between sediment yield and runoff power is the best at the height of 2 groove slope, the flow velocity and unit runoff power are the second, the runoff shear stress is the worst, and the runoff power is the relationship between the runoff yield and the sediment yield under the test condition. The best hydrodynamic parameters and power sources.
【學位授予單位】：西北農(nóng)林科技大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：S157.1

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