天然河道垂線流速分布類型及其影響因素初探
發(fā)布時間：2018-10-19 18:11
【摘要】：天然河道中的水流均為非恒定流,當前,河道非恒定問題日益突出。由于明渠非恒定流本身較為復雜,對明渠非恒定流的很多特性方面的研究一直未能有較大的突破。研究天然河道的垂線流速分布類型及其影響因素。對正確的掌握流速垂線分布規(guī)律及天然河流河床演變、水利學科的發(fā)展以及港口、航運及城市防洪等實際問題的解決,都有重要的理論和工程意義。為探討天然河道的垂線流速分布類型,本文以室內(nèi)ADV清水試驗和長江螃蟹磧至冰盤磧水道實測資料為基礎(chǔ),分別研究其流速分布形態(tài),對比找出主要影響因素。采用不同的計算公式對研究河段的推移質(zhì)輸沙率進行計算。通過對垂線流速分布和推移質(zhì)輸沙率、地形坡降和流量的關(guān)系探討,進一步明確天然河道垂線分布的類型及其影響因素,得到主要研究結(jié)論如下:(1)通過室內(nèi)ADV清水水槽試驗,在沒有外界因素的干擾下,清水非恒定流流速剖面為常規(guī)的“上大下小”型,其流速分布滿足傳統(tǒng)的對數(shù)分布。(2)以長江螃蟹磧至冰盤磧水道為研究對象,基于大量實測流速資料,天然河流的非常規(guī)流速分布可歸納總結(jié)為7種類型,分別為“3”型、“C”型、“1”型、“S”型、“7”型、“反S”型和“反C”型。(3)初步分析認為“7”型垂線流速多出現(xiàn)在地形陡升處�！�1”型垂線流速多出現(xiàn)在河床洼地的中心處�！癈”型垂線流速常出現(xiàn)于河道沿水流方向縮窄、洪峰陡漲以及挖槽和港池的出口等處�！胺碈”型垂線流速常出現(xiàn)在雍水水庫的回水末端、河道沿水流方向展寬、河道洪水陡落、挖槽和港池進口等處�！癝”型與“反S”型垂線流速多出現(xiàn)于河道近岸的有植被地帶。(4)研究河段垂線流速分布形態(tài)絕大多數(shù)呈“3”形分布,此流速分布模式多出現(xiàn)在地形較平坦的河道主流區(qū),由于長江河道寬闊,河道主流區(qū)流速不受兩岸邊壁及植被影響,初步分析認為天然河道水流的紊動性為該種分布模式形成的主要原因。(5)在垂線平均、最大流速和推移質(zhì)輸沙率的內(nèi)在關(guān)系分析得出,研究河段垂線平均、最大流速和推移質(zhì)輸沙率變化情況具有良好的一致性,二者成嚴格的線性關(guān)系。(6)在垂線平均、最大流速和地形坡降的內(nèi)在關(guān)系分析得出,研究河段垂線平均、最大流速和地形縱、橫坡降變化情況具有較好的一致性。垂線平均流速與地形縱坡降成嚴格的二次函數(shù)關(guān)系,與地形橫坡降的相關(guān)性較差。(7)分別將不同流量情況下的垂線平均流速和垂線最大流速進行對比分析可知,垂線平均流速和垂線最大流速均隨著流量的增加而增大。各斷面測點平均流速和最大流速增幅不一,初步分析認為,這是由于各斷面形狀不一以及各斷面上下游地形變化導致。
[Abstract]:The flow in natural river is unsteady, and the unsteady problem is becoming more and more serious. Due to the complexity of the unsteady flow in the open channel, there has been no great breakthrough in the study of many characteristics of the unsteady flow in the open channel. The vertical velocity distribution of natural river and its influencing factors are studied. It is of great theoretical and engineering significance to correctly grasp the distribution law of velocity perpendicular to the evolution of natural river bed, the development of water conservancy discipline and the solution of practical problems such as port, shipping and urban flood control. In order to study the vertical velocity distribution type of natural river channel, based on the indoor ADV water test and the measured data of the Yangtze River crab moraine to glacial drift, the velocity distribution pattern of the river is studied, and the main influencing factors are found out. Different formulas are used to calculate the bed load transport rate of the studied reach. By discussing the relationship between vertical velocity distribution and bed load transport rate, topographic slope gradient and discharge, the types of perpendicular distribution of natural river and its influencing factors are further clarified. The main conclusions are as follows: (1) through indoor ADV clean water flume test, In the absence of external interference, the flow velocity profile of the unsteady flow in clear water is a conventional "upper, larger and lower" type, and its velocity distribution satisfies the traditional logarithmic distribution. (2) the Yangtze River crab moraine to glacial moraine channel is taken as the research object. Based on a large number of measured velocity data, the unconventional velocity distribution of natural rivers can be summarized into seven types, which are "3", "C", "1", "S", "7", respectively. (3) A preliminary analysis shows that the velocity of "7" vertical line appears in steep elevation of terrain, "1" type perpendicular velocity occurs mostly in the center of riverbed depression, and "C" type perpendicular velocity often occurs in river. The channel narrows along the direction of the current, Hong Feng rose sharply, as well as dredging and the outlet of the harbour pool and so on. The "anti-C" vertical velocity often appears at the end of the backwater in Yongshui Reservoir. The channel widens along the direction of the flow, and the river flood drops precipitously. The vertical velocity of "S" type and "anti-S" type are mostly found in the vegetated zone near the river channel. (4) the distribution of velocity distribution of vertical line in the river reaches is mostly "3" shape. The velocity distribution pattern mostly appears in the flat river channel mainstream area. Because the Yangtze River channel is wide, the flow velocity in the main river channel is not affected by the side wall and vegetation on both banks. The primary analysis shows that the turbulence of natural river flow is the main reason for the formation of the distribution model. (5) the relationship between the maximum velocity of velocity and the rate of bed load transport in the vertical line is analyzed. The results show that the average vertical line of the river reaches is studied. The variation of maximum velocity and bed load transport rate is in good agreement, and they are in strict linear relationship. (6) in the vertical line average, the relationship between maximum velocity and topographic gradient is analyzed, and the perpendicular average of the river reach is studied. The maximum velocity of flow and the variation of vertical and transverse slope have good consistency. The relationship between the average velocity of the vertical line and the vertical gradient of the terrain is strictly quadratic, and the correlation between the average velocity of the vertical line and the gradient of the vertical slope is poor. (7) the comparison and analysis of the average velocity of the vertical line and the maximum velocity of the vertical line under different flow rates are made. Both the average velocity of the vertical line and the maximum velocity of the vertical line increase with the increase of the flow rate. The average velocity and the maximum velocity increase of each section are different. The preliminary analysis shows that this is due to the different shape of each section and the topographic variation of the upper and lower reaches of each section.
【學位授予單位】：重慶交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TV133
本文編號：2281941
[Abstract]:The flow in natural river is unsteady, and the unsteady problem is becoming more and more serious. Due to the complexity of the unsteady flow in the open channel, there has been no great breakthrough in the study of many characteristics of the unsteady flow in the open channel. The vertical velocity distribution of natural river and its influencing factors are studied. It is of great theoretical and engineering significance to correctly grasp the distribution law of velocity perpendicular to the evolution of natural river bed, the development of water conservancy discipline and the solution of practical problems such as port, shipping and urban flood control. In order to study the vertical velocity distribution type of natural river channel, based on the indoor ADV water test and the measured data of the Yangtze River crab moraine to glacial drift, the velocity distribution pattern of the river is studied, and the main influencing factors are found out. Different formulas are used to calculate the bed load transport rate of the studied reach. By discussing the relationship between vertical velocity distribution and bed load transport rate, topographic slope gradient and discharge, the types of perpendicular distribution of natural river and its influencing factors are further clarified. The main conclusions are as follows: (1) through indoor ADV clean water flume test, In the absence of external interference, the flow velocity profile of the unsteady flow in clear water is a conventional "upper, larger and lower" type, and its velocity distribution satisfies the traditional logarithmic distribution. (2) the Yangtze River crab moraine to glacial moraine channel is taken as the research object. Based on a large number of measured velocity data, the unconventional velocity distribution of natural rivers can be summarized into seven types, which are "3", "C", "1", "S", "7", respectively. (3) A preliminary analysis shows that the velocity of "7" vertical line appears in steep elevation of terrain, "1" type perpendicular velocity occurs mostly in the center of riverbed depression, and "C" type perpendicular velocity often occurs in river. The channel narrows along the direction of the current, Hong Feng rose sharply, as well as dredging and the outlet of the harbour pool and so on. The "anti-C" vertical velocity often appears at the end of the backwater in Yongshui Reservoir. The channel widens along the direction of the flow, and the river flood drops precipitously. The vertical velocity of "S" type and "anti-S" type are mostly found in the vegetated zone near the river channel. (4) the distribution of velocity distribution of vertical line in the river reaches is mostly "3" shape. The velocity distribution pattern mostly appears in the flat river channel mainstream area. Because the Yangtze River channel is wide, the flow velocity in the main river channel is not affected by the side wall and vegetation on both banks. The primary analysis shows that the turbulence of natural river flow is the main reason for the formation of the distribution model. (5) the relationship between the maximum velocity of velocity and the rate of bed load transport in the vertical line is analyzed. The results show that the average vertical line of the river reaches is studied. The variation of maximum velocity and bed load transport rate is in good agreement, and they are in strict linear relationship. (6) in the vertical line average, the relationship between maximum velocity and topographic gradient is analyzed, and the perpendicular average of the river reach is studied. The maximum velocity of flow and the variation of vertical and transverse slope have good consistency. The relationship between the average velocity of the vertical line and the vertical gradient of the terrain is strictly quadratic, and the correlation between the average velocity of the vertical line and the gradient of the vertical slope is poor. (7) the comparison and analysis of the average velocity of the vertical line and the maximum velocity of the vertical line under different flow rates are made. Both the average velocity of the vertical line and the maximum velocity of the vertical line increase with the increase of the flow rate. The average velocity and the maximum velocity increase of each section are different. The preliminary analysis shows that this is due to the different shape of each section and the topographic variation of the upper and lower reaches of each section.
【學位授予單位】：重慶交通大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TV133
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