發(fā)布時(shí)間：2018-01-24 00:40

  本文關(guān)鍵詞： 山區(qū)河流 泥沙補(bǔ)給 河床變形 水位陡增 水沙災(zāi)害　出處：《工程科學(xué)與技術(shù)》2017年S1期 　論文類(lèi)型：期刊論文

【摘要】：山區(qū)河流受季節(jié)性水文條件及產(chǎn)沙過(guò)程的影響,水沙條件變化頻繁。尤其是暴雨山洪頻繁挾帶大量泥沙進(jìn)入河道,從而引起河床急劇調(diào)整。本文以龍溪河典型河段為研究對(duì)象,通過(guò)調(diào)查天然河道的地形、床沙組成及來(lái)水來(lái)沙特性,開(kāi)展系列水沙模型試驗(yàn),突出分析來(lái)水來(lái)沙條件變化的河床響應(yīng)。試驗(yàn)包括不同流量下清水沖刷和恒定流量下改變泥沙補(bǔ)給條件兩種對(duì)比方案。以泥沙起動(dòng)條件的沙莫夫公式判定方法,分析比較了不同工況條件下的斷面泥沙起動(dòng)流速和水流運(yùn)動(dòng)平均流速的關(guān)系,揭示不同斷面間泥沙沖淤特性及河床變形特點(diǎn)。在此基礎(chǔ)上,探討河道沿程水位變化及致災(zāi)范圍,對(duì)比分析表明,龍溪河在清水來(lái)流條件下,即使通過(guò)最大流量300 m3/s,洪水位也未超過(guò)龍池鎮(zhèn)堤防高程,即清水來(lái)流條件一般不會(huì)影響龍池鎮(zhèn)的防洪安全。若大量泥沙下泄至主河道,龍池鎮(zhèn)段由于河床比降變緩與河道展寬等床面形態(tài)的變化,水流平均流速顯著降低,攜沙能力減小,引起大量泥沙淤積,致使水位陡增,甚至出現(xiàn)漫灘現(xiàn)象,存在顯著的防洪安全隱患。隨著泥沙補(bǔ)給量的不斷增加,河床不同區(qū)域輸沙動(dòng)力的調(diào)整制約了泥沙的輸移距離,從而引起局部區(qū)域河床的淤堵,并導(dǎo)致洪水位的增加,甚至產(chǎn)生漫灘洪水并誘發(fā)洪水災(zāi)害。研究表明,山區(qū)河流泥沙補(bǔ)給對(duì)河床響應(yīng)及水沙災(zāi)害具有重大的影響,來(lái)水來(lái)沙變化下的水沙運(yùn)動(dòng)致災(zāi)機(jī)理亟需深入研究。
[Abstract]:Influenced by the seasonal hydrological conditions and sediment yield, the water and sediment conditions change frequently in mountain rivers, especially the heavy rain torrential torrents frequently carry a large amount of sediment into the channel. This paper takes the typical reach of Longxi River as the research object, and carries out a series of water and sediment model tests by investigating the topography, the composition of bed sediment and the characteristics of incoming water and sediment. The experiment includes two contrast schemes: clean water scour under different flow rate and changing sediment recharge condition at constant flow. The method of determining sediment incipient condition by Shamoff formula is presented. The relationship between the initial velocity of sediment and the average velocity of water flow under different working conditions is analyzed and compared to reveal the characteristics of sediment scouring and silting and the characteristics of river bed deformation among different sections. In this paper, the variation of water level along the river course and the range of disasters are discussed. The comparative analysis shows that the flood water level of Longxi River does not exceed the elevation of Longchi Town embankment even though the maximum discharge is 300 m3 / s under the condition of clear water flow. If a large amount of sediment is released to the main river, the river bed shape of Longchi Town will change due to the slowing down of the river bed ratio and the widening of the river channel. The average velocity of flow decreased significantly, and the sediment carrying capacity decreased, resulting in a large amount of sediment deposition, resulting in a steep increase in water level, even the phenomenon of flooding, there are significant flood control safety risks, with the continuous increase of sediment supply. The adjustment of sediment transport power in different areas of river bed restricts the distance of sediment transport, thus causing the siltation of the river bed in some areas, and leading to the increase of flood water level, even causing floodplain flood and inducing flood disaster. Sediment recharge in mountain rivers has great influence on river bed response and flood and sediment disasters. The mechanism of water and sediment movement induced by changes of incoming water and sediment needs to be studied in depth.
【作者單位】： 四川大學(xué)水力學(xué)與山區(qū)河流開(kāi)發(fā)保護(hù)國(guó)家重點(diǎn)實(shí)驗(yàn)室水利水電學(xué)院;
【基金】：國(guó)家自然科學(xué)基金資助項(xiàng)目(51579163;51639007) 國(guó)家重點(diǎn)研發(fā)計(jì)劃重點(diǎn)資助項(xiàng)目(2016YFC0402302)
【分類(lèi)號(hào)】：TV14
【正文快照】： 山區(qū)流域暴雨山洪頻發(fā),并且響應(yīng)時(shí)間短、水流速度高、沖擊力大,會(huì)造成坡溝失穩(wěn)破壞、坡體滑塌、溝床下切,同時(shí)挾帶大量泥沙輸送至河道下游。而山區(qū)流域水系發(fā)育豐富,河網(wǎng)密度大,河床比降變化劇烈,顆粒起動(dòng)條件變化差異顯著,致使泥沙在局部區(qū)域發(fā)生明顯的淤堵,降低河流的排洪輸

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