本文關(guān)鍵詞： 不同活躍程度 沖溝侵蝕 土體抗沖性 影響因素 干熱河谷　出處：《四川農(nóng)業(yè)大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：沖溝侵蝕是造成元謀干熱河谷生態(tài)環(huán)境脆弱、水土流失嚴(yán)重等問題的主要根源之一：土壤抗沖性是揭示土壤侵蝕機(jī)理的重要指標(biāo),也是土壤侵蝕領(lǐng)域的研究熱點(diǎn)和難點(diǎn)問題之一。開展干熱河谷極端環(huán)境(特殊的氣候條件、復(fù)雜的巖土性質(zhì))下土體抗沖性研究,從抗沖性指數(shù)的空間分布特征揭示沖溝侵蝕規(guī)律,為區(qū)域生態(tài)修復(fù)與水土保持工作提供理論指導(dǎo)。為探明干熱河谷不同活躍程度沖溝土體的抗沖性能,本研究選取活躍、較活躍和穩(wěn)定這三類沖溝的溝頭、溝床及其集水區(qū)的表層土體,設(shè)置了0%,50%和100%三個(gè)不同初始含水率的處理。采用原狀土水槽沖刷試驗(yàn)和室內(nèi)理化性質(zhì)分析實(shí)驗(yàn)的方法,研究了不同活躍程度沖溝土體的理化性質(zhì)差異、不同部位土體抗沖性變化特征、不同初始含水率條件下沖溝土體抗沖系數(shù)動(dòng)態(tài)變化特征,并分析了沖溝土體抗沖性的影響因素。研究結(jié)果表明：(1)隨沖溝活躍程度從活躍、較活躍到穩(wěn)定狀態(tài)變化,沖溝土體的理化性質(zhì)相應(yīng)發(fā)生變化。不同活躍程度沖溝土體理化性質(zhì)大小為：土體容重、砂粒含量、內(nèi)摩擦角在活躍沖溝最大,在穩(wěn)定沖溝最小,表現(xiàn)為活躍較活躍沖溝穩(wěn)定沖溝：土體總孔隙度、田間持水率、粘聚力、粉粒含量、粘粒含量則相反,其含量高低依次為活躍沖溝較活躍沖溝穩(wěn)定沖溝。(2)不同活躍程度沖溝發(fā)育區(qū)各部位(溝頭、溝床和集水區(qū))的徑流含沙量均隨時(shí)間的增加而減小。三類沖溝的徑流含沙量為活躍沖溝較活躍沖溝穩(wěn)定沖溝：不同活躍度沖溝主要產(chǎn)沙部位也不大一致,活躍和較活躍沖溝產(chǎn)沙部位主要為溝頭,穩(wěn)定沖溝主要產(chǎn)沙部位為溝床。(3)不同初始含水率條件下土體抗沖性均與時(shí)間呈現(xiàn)冪函數(shù)遞增關(guān)系。初始含水率為0%條件下,沖溝發(fā)育區(qū)各部位抗沖性大小表現(xiàn)為：活躍沖溝集水區(qū)溝床溝頭,較活躍沖溝溝床集水區(qū)溝頭,穩(wěn)定沖溝溝頭溝床集水區(qū)；初始含水率為50%條件下,沖溝各部位抗沖性大小為：活躍沖溝集水區(qū)溝床溝頭,較活躍沖溝溝床集水區(qū)溝頭,穩(wěn)定沖溝溝頭溝床集水區(qū)；初始含水率為100%時(shí)各部位抗沖性大小表現(xiàn)為活躍沖溝溝床集水區(qū)溝頭,較活躍集水區(qū)溝床溝頭,穩(wěn)定沖溝溝床溝頭集水區(qū)。表明干熱河谷區(qū)沖溝在不同含水率下,活躍和較活躍沖溝的溝頭、穩(wěn)定沖溝的集水區(qū)土體抗沖性最小,極易受徑流沖刷侵蝕,應(yīng)重點(diǎn)治理活躍、較活躍沖溝溝頭,重視穩(wěn)定沖溝集水區(qū)的保護(hù)。(4)在不同含水率條件下沖溝土體抗沖性的影響因素不盡相同�；钴S沖溝土體抗沖性與抗剪強(qiáng)度(內(nèi)摩擦角、黏聚力)、黏粒含量與各類生物多樣性指標(biāo)顯著正相關(guān),與砂粒含量顯著負(fù)相關(guān)；較活躍沖溝土體抗沖性與Simpson指數(shù)、豐富度、多度顯著正相關(guān),與砂粒含量顯著負(fù)相關(guān)；穩(wěn)定沖溝抗沖性與黏粒含量顯著正相關(guān),與田間持水率、粉粒含量、砂粒含量和生物多樣性指標(biāo)顯著負(fù)相關(guān)。
[Abstract]:Gully erosion is one of the main causes of the fragile ecological environment and serious soil erosion in Yuanmou dry-hot valley. Soil erosion resistance is an important index to reveal the mechanism of soil erosion. It is also one of the hot and difficult problems in the field of soil erosion. Based on the spatial distribution characteristics of scour resistance index, the rule of gully erosion is revealed, which provides theoretical guidance for regional ecological restoration and soil and water conservation. In order to find out the scour resistance of gully soil with different active degree in dry and hot valley, this study is active. The surface soil of the trench bed and its catchment is more active and stable. Three different initial moisture contents of 0 ~ (50%) and 100% (100%) are set up. The methods of flume scour test and laboratory physical and chemical property analysis experiment are used. The physical and chemical properties of gully soil with different active degree, the characteristics of soil erosion resistance in different parts and the dynamic change characteristics of scour resistance coefficient of gully soil under different initial moisture content were studied. The influence factors of scour resistance of gully soil are analyzed. The results show that the crevasse activity changes from active, active to stable state. The physical and chemical properties of the gully soil are changed accordingly. The physical and chemical properties of the gully soil with different active degrees are as follows: the bulk density of soil, the content of sand particles, the angle of internal friction are the largest in the active gully and the smallest in the stable gully. The results showed that the stable gullies were active and active: soil total porosity, field water holding capacity, cohesion, silt content and clay content were opposite. The order of its content is active gully, active gully, stable gully. The sediment content of runoff decreased with the increase of time. The sediment content of the three types of gullies is active gullies, which are more stable than active gullies, and the main sediment production sites of different active gullies are not consistent. The main sediment yield of active and active gullies is gully head, and the main sediment yield part of stable gully is trench bed. (3) under the condition of different initial water content, the anti-scouring ability of soil is increased by power function. When the initial water content is 0%, the erosion resistance of soil is increased by power function. The erosion resistance of various parts of the gully development area is as follows: the trench bed head in the active gully catchment area, the trench head in the catchment area of the active trench bed, the stable gully trench bed catchment area, the initial water content being 50%, The erosion resistance of every part of the gully is as follows: active gully catchment area, trench bed catchment area, steady gully trench bed catchment area; When the initial water content is 100, the erosion resistance of every part is shown as active trench bed catchment, more active catchment area, and stable gully bed catchment area, which indicates that the gully in dry and hot valley area is under different water content. The active and active gully head, the soil body in the stable gully catchment area has the least scour resistance and is vulnerable to runoff erosion, so it is necessary to control the active gully head, the more active gully head, the more active gully head, the more active gully head, the more active gully head, Paying attention to the protection of stable gully catchment. 4) the influence factors of scour resistance of gully soil under different water content are different. The scouring resistance and shear strength of active gully soil (internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, internal friction angle, etc.). The content of clay is positively correlated with various biodiversity indexes and negatively correlated with sand content, and is positively correlated with Simpson index, abundance and abundance of active gully soil, and negatively correlated with sand content. The scour resistance of stable gully was positively correlated with clay content, negatively correlated with field water holding rate, silt content, sand content and biodiversity index.
【學(xué)位授予單位】：四川農(nóng)業(yè)大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：S157.1

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