發(fā)布時(shí)間：2018-07-05 09:44

  本文選題：無壓隧洞 + 階梯式消能工　； 參考：《武漢大學(xué)》2014年博士論文

【摘要】：隧洞作為水利樞紐泄洪的主要建筑物之一,在泄洪中發(fā)揮著重要的作用,但很多無壓隧洞受到地形和地質(zhì)因素的影響,不僅底坡較大,而且洞身較長,隧洞進(jìn)出口水頭差較大,水流入洞后流速很快超過16m/s,屬于高流速隧洞[7],因此需要設(shè)置消能工進(jìn)行能量控制。傳統(tǒng)的消能方式只能在隧洞進(jìn)口之前和出口之后發(fā)揮作用,對(duì)洞身不能起到保護(hù)作用。另外部分工程由于地形限制,下游沒有足夠空間修筑底流消能工,且不具備挑流消能條件,如果能在洞內(nèi)采用階梯消能工,將隧洞中將大量能量消殺掉,就可以為工程帶來巨大的效益。 本文通過模型試驗(yàn)結(jié)合數(shù)值模擬的研究方法,從水流流況、流態(tài)、水面線、階梯水平面和階梯豎直面的時(shí)均壓力和脈動(dòng)壓力、斷面水深方向以及沿程階梯摻氣特性、絕對(duì)消能效果等方面對(duì)水工隧洞階梯消能機(jī)理及水力特性進(jìn)行較為系統(tǒng)的研究,論文主要內(nèi)容如下： 1.水工隧洞階梯消能的流況研究。本文提出水工隧洞階梯消能水流可分為跌落水流、過渡水流、滑行水流三種流況,水工隧洞中水流弗氏數(shù)的變化范圍較溢洪道要廣泛許多,試驗(yàn)中觀察到在單寬流量相同的條件下,泄槽首部弗氏數(shù)不同,沿程階梯會(huì)出現(xiàn)不同的流況,指出流況界限與泄槽首部水流弗氏數(shù)有密切聯(lián)系,提出跌落水流和滑行水流界限的經(jīng)驗(yàn)公式。 2.隧洞階梯消能工首部設(shè)置較小的楔形階梯對(duì)水流影響的研究。在首部設(shè)置較小的楔形階梯,如前3級(jí)階梯高度h=0.5m,3-10級(jí)階梯h=0.5-1.0m,10級(jí)以后h=1.0-2.0m,同時(shí)將首部階梯水平面設(shè)置為向下游傾斜的楔形階梯,然后漸變?yōu)樗诫A梯。這樣一方面可以降低發(fā)生滑行水流的單寬流量,使水流容易發(fā)生滑行水流；另一方面,楔形階梯減小跌落水舌與階梯水平面的夾角,從而減小水舌與底板之間的沖擊力,使得水面較平穩(wěn),從而改善了挑射水流等不利流態(tài)。 3.連續(xù)坎后設(shè)置圓弧形底坡或者渥奇曲線底坡解決摻氣坎后積水問題的研究。緩底坡低Fr數(shù)水流很容易出現(xiàn)摻氣坎積水問題,研究發(fā)現(xiàn)挑射水舌需落在弧形底坡或者渥奇曲線底坡的中部偏尾部,否則曲線形底坡不能起到抑制水流回溯的作用。圓弧型底坡或者渥奇曲線底坡體型,在相同水平長度下,曲線的高差越大,越有利消除積水。渥奇曲線相對(duì)圓弧曲線底坡,首部坡度小、中后部坡度大,比圓弧曲線更能抑制水流的回溯,完全消除空腔內(nèi)的積水,提高摻氣槽的摻氣效率。 4.摻氣坎通氣量qs與單寬流量q以及水流弗氏數(shù)Fr三者之間關(guān)聯(lián)規(guī)律的研究。通過系統(tǒng)的研究,提出相應(yīng)的經(jīng)驗(yàn)公式。工程設(shè)計(jì)中,根據(jù)工程運(yùn)行時(shí)最大的流量,以及水流運(yùn)行時(shí)可能出現(xiàn)的最大弗氏數(shù),計(jì)算出摻氣坎通氣量,確定摻氣槽尺寸。 5.摻氣均勻點(diǎn)位置以及隧洞階梯消能工摻氣特性研究。研究發(fā)現(xiàn),摻氣均勻點(diǎn)距離摻氣坎的距離Ls/h與摻氣坎上游處水流的流能比F之間具有一定的函數(shù)關(guān)系,作者提出自己的經(jīng)驗(yàn)公式。單個(gè)階梯沿水深方向的摻氣規(guī)律為：摻氣濃度從底板至水面的規(guī)律為0.1-0.3倍水深區(qū)間先緩慢增大,在0.4-0.6倍水深區(qū)間,摻氣濃度有較大幅度的減小,在0.8倍水深至水面處時(shí),摻氣濃度逐漸增加。隨著單寬流量的增加,水深方向整體摻氣濃度減小,隨著水流弗氏數(shù)、底坡坡度、階梯高度的增大整體摻氣濃度增加。其中弗氏數(shù)的變化,對(duì)上游階梯中部水深摻氣濃度影響較顯著,底坡坡度和階梯高度對(duì)同一斷面沿水深方向的摻氣濃度分布規(guī)律基本無影響,底坡坡度對(duì)水流表面和中部的摻氣濃度影響較底部要大。 6.沿程階梯水流弗氏數(shù)變化規(guī)律的研究。研究發(fā)現(xiàn)水流平均弗氏數(shù)在階梯首部波動(dòng)較大,沿程會(huì)逐漸趨于穩(wěn)定。單寬流量越大,沿程階梯弗氏數(shù)越早趨于穩(wěn)定,且穩(wěn)定后相對(duì)弗氏數(shù)f2/Fr1越大。隨著泄槽首部弗氏數(shù)的提升,沿程階梯相對(duì)弗氏數(shù)顯著降低,沿程階梯弗氏數(shù)越較早的達(dá)到穩(wěn)定值。隨著底坡和階梯高度的增加,沿程階梯相對(duì)弗氏數(shù)逐漸增大,沿程波動(dòng)性越大,弗氏數(shù)達(dá)到穩(wěn)定的位置相應(yīng)滯后。下游水流相對(duì)弗氏數(shù)一般在10級(jí)左右階梯處達(dá)到穩(wěn)定值。 7.水工隧洞階梯消能率計(jì)算公式的研究。從階梯消能工絕對(duì)消能率的公式出發(fā),在泄槽首部水流條件一定的條件下,等價(jià)的推導(dǎo)出沿程階梯的絕對(duì)消能率為下游階梯水流斷面平均弗氏數(shù)Fr2的函數(shù)。系統(tǒng)的研究單寬流量q、泄槽首部水流弗氏數(shù)Fr1、底坡坡度i、階梯高度h對(duì)沿程階梯處水流弗氏數(shù)Fr2的影響,從而推導(dǎo)出絕對(duì)消能率的計(jì)算公式,計(jì)算公式與實(shí)測數(shù)據(jù)吻合,從本質(zhì)上指出階梯消能過程就是減小沿程水流弗氏數(shù)。 8.水工隧洞階梯消能率影響因素的研究。從階梯布置長度、單寬流量、水流弗氏數(shù)、底坡坡度、階梯高度等影響因素進(jìn)行研究。隨著階梯布置長度的增加,沿程消能率呈現(xiàn)非線性的增大,增長速度逐漸變慢。在沿程階梯的同一部位,隨著流量的增大,消能率逐漸減小,隨著泄槽底坡的增大,消能率基本呈現(xiàn)線性減小,隨著泄槽首部水流弗氏數(shù)的增大,同一部位的消能率呈現(xiàn)先降低后有所回升,弗氏數(shù)的改變顯著的影響上游階梯的消能率,對(duì)尾部階梯消能率影響不明顯。當(dāng)沿程階梯水流弗氏數(shù)達(dá)到穩(wěn)定值后,同一部位的消能率基本與階梯高度無關(guān)。同時(shí)研究結(jié)果表明不能明確的判別跌落水流和滑行水流的消能率何者更優(yōu),三種流況的消能率大小要根據(jù)引起流況改變的因素來判別。 9.水工隧洞階梯消能工設(shè)計(jì)中合適的階梯布置長度和階梯體型的研究。從函數(shù)的增減性可以推斷,消能率η是相對(duì)斷面高差△H1-2/y1的單調(diào)遞增凹函數(shù)。在階梯長度布置達(dá)到一定長度后,繼續(xù)增加階梯長度來提高消能率是不經(jīng)濟(jì)的。階梯高度較大時(shí),沿程階梯水流波動(dòng)性較大,沿程階梯弗氏數(shù)達(dá)到穩(wěn)定所需要的階梯數(shù)量較多,考慮到弗氏數(shù)達(dá)到穩(wěn)定值后,階梯高度對(duì)消能率基本無影響,因而在設(shè)計(jì)階梯消能工時(shí),首部階梯采用較小楔形階梯。坡度較陡且單寬流量較大時(shí),要達(dá)到較高的消能率,需要布置較多的階梯,約50-130級(jí)階梯,在實(shí)際工程中施工的工程量較多,這類工程基本不適合采用階梯消能工。 10.水工隧洞階梯消能工空蝕、沖刷、振動(dòng)等安全性問題的研究。時(shí)均壓力和脈動(dòng)壓力是引起以上安全性問題關(guān)鍵因素。本文系統(tǒng)從單寬流量、水流弗氏數(shù)、底坡坡度、階梯高度四個(gè)主要影響因素對(duì)階梯水平面和豎直面的時(shí)均壓力、脈動(dòng)壓強(qiáng)強(qiáng)度、脈動(dòng)壓強(qiáng)最大及最小瞬時(shí)值、脈動(dòng)功率譜等水力參數(shù)進(jìn)行研究。研究結(jié)果表明：階梯水平面最大值時(shí)均壓強(qiáng)p/h=3.5,最大瞬時(shí)壓強(qiáng)p/h=9.5。第一級(jí)階梯凸角最大負(fù)壓p/h=-0.8,沿程階梯最大負(fù)壓p/h=-0.6,沿程階梯凸角區(qū)域脈動(dòng)壓強(qiáng)最小瞬時(shí)值p/h=-2.5m。在水流摻氣充分的情況下,階梯水平面最大正壓及階梯豎直面最大負(fù)壓均在混凝土的安全承受能力范圍內(nèi),基本不會(huì)出現(xiàn)空蝕沖刷破壞。階梯消能工上水流的脈動(dòng)主頻與階梯邊壁、底板固有頻率相差較大,不會(huì)引起階梯消能工的強(qiáng)烈振動(dòng)。 實(shí)際水工隧洞中設(shè)計(jì)階梯階梯消能工時(shí),階梯體型和階梯布置長度要綜合考慮流態(tài)、摻氣特性、消能效果,單方面的追求高消能率會(huì)增加不必要的成本。如果水工隧洞空間充足,應(yīng)盡量使水流形成滑行水流,中部及下游階梯水流進(jìn)入充分摻氣區(qū),同時(shí)控制水工隧洞出口的消能率,使其在與下游水流銜接時(shí)不對(duì)下游河床和岸坡造成沖刷破壞。如果水工隧洞空間受到限制,首先考慮消能效果和水流流態(tài),其次考慮能否使水流均勻摻氣。
[Abstract]:As one of the main buildings in flood discharge, the tunnel plays an important role in flood discharge. However, many non pressure tunnels are affected by terrain and geological factors, not only the bottom slope is larger, but also the hole is long, and the head of the tunnel has a long head difference. The flow velocity of the tunnel is faster than 16m/s, and it belongs to the high velocity tunnel [7]. Therefore, it is necessary to set up a high velocity tunnel. The traditional energy dissipation method can only play the role before and after the entrance and exit of the tunnel, and can not protect the hole. In the other part of the project, there is not enough space to build the bottom flow energy dissipator in the downstream, and the downstream energy dissipation conditions are not enough, and if the stair energy dissipator can be used in the tunnel, the energy dissipator can be used in the tunnel. A large amount of energy will be killed in the tunnel, which will bring great benefits to the project.
In this paper, through the method of model test and numerical simulation, the time average pressure and pulsation pressure of water flow state, flow state, water surface line, step horizontal plane and staircase vertical face, the direction of the depth of section water, the aeration characteristics along the ladder and the absolute energy dissipation effect on the energy dissipation mechanism and hydraulic characteristics of the staircase of hydraulic tunnel are comparatively systematic. The main contents of the thesis are as follows:
Study on the flow of staircase energy dissipation in 1. hydraulic tunnels. This paper proposes that the staircase energy dissipation flow of the hydraulic tunnel can be divided into three kinds of flow conditions, such as falling water, transition flow, and gliding flow. The variation range of the number of Freudian flow in the hydraulic tunnel is much wider than that in the spillway. There will be different flow conditions along the staircase, and it is pointed out that the flow condition is closely related to the first flow of the flute, and the empirical formula of the boundary between the falling water flow and the sliding flow is put forward.
The first part of the 2. tunnel staircase energy dissipator is the first to set up a small wedge step to study the influence of the flow on the flow. In the first set of smaller wedge-shaped steps, such as the first 3 step height h=0.5m, the 3-10 step h=0.5-1.0m, and the later h=1.0-2.0m, the first step horizontal plane is set to the downstream wedge ladder and then gradually to the horizontal step. On the one hand, the single wide flow of the sliding flow can be reduced and the flow of water can easily occur. On the other hand, the wedge step reduces the angle between the falling water tongue and the horizontal plane, thus reducing the impact force between the water tongue and the bottom plate, making the water surface more stable, thus improving the unfavorable flow and so on.
The research on the problem of water accumulation after the aeration ridge is solved by setting the circular arc bottom slope or the bottom slope of Walch curve after 3. continuous sill. The problem of water aeration is easy to appear at low Fr number flow in slow bottom slope. It is found that the pitched water tongue should fall on the bottom of the curved bottom slope or the bottom of the bottom slope of the Walch curve, and the curve bottom slope can not be used to suppress the backtracking of the flow. In the same horizontal length, the higher the height difference of the curve, the greater the height difference of the curve, the more favorable to eliminate the water accumulation. The lower slope of the walker curve is relative to the arc curve, the lower slope of the first part, the larger slope in the middle and the rear, can restrain the backtracking of the flow more than the arc curve, completely eliminate the water accumulation in the cavity and improve the aeration efficiency of the aerated trough. Rate.
The study of the correlation between the 4. gas flow rate QS and the single wide flow Q and the flick number Fr three. Through the systematic study, the corresponding empirical formula is put forward. In the engineering design, the air volume of aeration and the size of the aeration tank are calculated according to the maximum flow rate and the maximum Freund number that may appear during the operation of the water.
It is found that there is a certain function relationship between the distance Ls/h of the air entrainment and the flow energy of the flow in the upstream of the aeration point Ls/h and the flow energy of the flow at the upper reaches of the aeration ridge. The author puts forward his own empirical formula. The air mixing law of a single step along the direction of water depth is: the concentration of aeration from the bottom to the bottom. The regularity of the plate to the water surface is a slow increase in the depth of 0.1-0.3 times, and the concentration of aeration is greatly reduced at the depth of 0.4-0.6 times. When the water depth is 0.8 times to the surface of the water, the concentration of aeration gradually increases. With the increase of the single width of the water, the concentration of the whole aeration in the direction of water depth decreases, with the increase of the number of water flow, the slope of the bottom and the step height. The change of Freund number has a significant influence on the air concentration in the upper reaches of the upper reaches of the upper reaches. The slope and step height of the bottom slope have no influence on the gas concentration distribution along the direction of water depth. The influence of the slope gradient on the air concentration in the flow surface and the middle is larger than that in the bottom.
The study of the change law of the number of Freund number in the 6. staircase flow. The study found that the average Freund number in the first part of the water flow fluctuates larger in the first part of the ladder, and gradually tends to be stable along the path. The greater the flow of the single width, the earlier the Freund number tends to be stable, and the relative Freudian number f2/Fr1 becomes larger after the stability. With the increase of the number of Freund numbers along the ladder, the number of Freund is gradually increased with the increase of the bottom slope and the ladder height, the greater the fluctuation along the path, the more stable position of the Freund number, and the relative fund number in the downstream water reaches a stable value at about 10 steps.
7. formula for calculating the staircase energy dissipation rate of hydraulic tunnel. Starting from the formula of absolute energy dissipation of staircase energy dissipator, under the condition of a certain flow condition of the first flow of the slots, the equivalent derivation of the absolute energy dissipation rate of the stepped staircase is a function of the average Freund number Fr2 of the downstream staircase flow section. The system has a single wide flow of Q and the first flute of the slots. The influence of the number of Fr1, the slope of the bottom slope I and the step height h on the number Fr2 of the flow in the staircase along the distance, thus derives the calculation formula of the absolute energy dissipation rate. The formula is in agreement with the measured data. In essence, it is pointed out that the step energy dissipation process is to reduce the number of Freund in the flow.
The study of factors affecting the staircase energy dissipation rate of 8. hydraulic tunnel. From step layout length, single width flow, flick number, bottom slope, step height and other influence factors. With the increase of the ladder length, the energy dissipation rate along the distance increases and the growth rate gradually slows down. In the same part of the ladder, with the flow rate The energy dissipation rate decreases gradually. With the increase of the bottom slope of the slots, the energy dissipation rate basically presents a linear decrease. With the increase of the first flow of the flute, the energy dissipation rate of the same part decreases first and then rises, and the change of the Freund number significantly affects the energy dissipation rate of the upper ladder, and the effect on the staircase energy dissipation rate is not obvious. At the same time, the energy dissipation rate of the same part is basically independent of the step height. At the same time, the results show that the energy dissipation rate of the falling water flow and the sliding flow can not be distinguished clearly. The energy dissipation rate of the three flow conditions should be judged according to the factors that cause the change of the flow condition.
The study of the appropriate ladder layout length and staircase shape in the design of 9. hydraulic tunnel staircase dissipator. From the increase and subtraction of the function, the energy dissipation rate is a monotonically increasing concave function of the relative height difference Delta H1-2/y1. After the ladder length is arranged to a certain length, it is not economical to continue to increase the step length to increase the energy dissipation rate. When the height is high, the fluctuation of the flow along the ladder is larger and the number of steps required to reach stability is more. Considering that the number reaches stable value, the ladder height has no effect on the energy dissipation. Therefore, the first step adopts a smaller wedge step in the design of staircase energy dissipation. When the slope is steep and the single width flow is larger, In order to achieve high energy dissipation, we need to arrange more steps, about 50-130 steps, and the amount of construction in the actual project is more. This kind of project is not suitable for the use of staircase energy dissipator.
10. research on safety problems such as cavitation, scouring and vibration of staircase energy dissipator in hydraulic tunnel. The time average pressure and pulsating pressure are the key factors to cause the above safety problems. In this paper, the time average pressure and pulsating pressure of four main influencing factors of the single wide flow, the flush number, the bottom slope and the staircase height, and the pulsating pressure Strength, pulsating pressure maximum and minimum instantaneous value, pulsating power spectrum and other hydraulic parameters are studied. The results show that the maximum value of the maximum value is p/h=3.5, the maximum instantaneous pressure is p/h=9.5. first step the maximum negative pressure p/h=-0.8, the maximum negative pressure is p/h =-0.6 along the step ladder, and the pulsating pressure in the region along the ladder is the minimum transient pressure. At the time value of p/h=-2.5m., the maximum positive pressure and the maximum negative pressure of the ladder vertical face are all within the safe bearing capacity of the concrete under the condition of full aeration of the water. The strong vibration of the working.
In the actual hydraulic tunnel, the staircase staircase energy dissipation is designed, the staircase shape and the ladder layout should take into consideration the flow state, the aeration characteristic and the energy dissipation effect. The unilateral pursuit of high energy dissipation will increase the unnecessary cost. If the hydraulic tunnel has sufficient space, the water flow should be formed into the sliding flow, and the middle and downstream staircase flows are fully entered. The aeration zone, at the same time, controls the energy dissipation rate of the outlet of the hydraulic tunnel, so that it does not destroy the downstream river bed and the bank slope when connecting with the downstream flow. If the hydraulic tunnel space is restricted, the energy dissipation effect and the flow pattern are considered first, and the flow of the flow can be evenly mixed.
【學(xué)位授予單位】：武漢大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TV672.1;TV135

【參考文獻(xiàn)】

相關(guān)期刊論文 前10條

1 陸芳春;史斌;包中進(jìn);;階梯式溢流面消能特性研究[J];長江科學(xué)院院報(bào);2006年01期

2 石教豪;韓繼斌;姜治兵;李學(xué)海;;臺(tái)階壩面消能水氣兩相流數(shù)值模擬[J];長江科學(xué)院院報(bào);2009年07期

3 汝樹勛，唐朝陽，梁川;曲線型階梯溢流壩壩面摻氣發(fā)生點(diǎn)位置的確定[J];長江科學(xué)院院報(bào);1996年02期

4 倪漢根;水流脈動(dòng)壓力的相似律[J];大連工學(xué)院學(xué)報(bào);1982年01期

5 陳宗梁;國外水電技術(shù)的發(fā)展[J];中國工程科學(xué);2002年04期

6 易曉華,盧紅;臺(tái)階式溢洪道及其在索風(fēng)營水電站的試驗(yàn)研究[J];貴州水力發(fā)電;2003年02期

7 劉玲玲;田士豪;段亞輝;;高低挑坎豎向差動(dòng)消能水力過渡過程初探[J];湖北水力發(fā)電;2006年01期

8 謝省宗，李世琴，李桂芬;寬尾墩聯(lián)合消能工在我國的發(fā)展（續(xù)）[J];紅水河;1996年01期

9 劉金輝;奚晶瑩;;臺(tái)階式溢流壩的消能設(shè)計(jì)與試驗(yàn)[J];吉林水利;2009年08期

10 鄒俊;鄔年華;;斜鼻坎、曲面貼角鼻坎、雙曲挑坎等幾種異型鼻坎挑流消能工的應(yīng)用研究[J];吉林水利;2012年12期

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