本文選題：水墊塘底板 + 異形構(gòu)造��； 參考：《天津大學(xué)》2014年碩士論文

【摘要】：我國(guó)水能可開(kāi)發(fā)量和建設(shè)規(guī)模均居世界首位。這些工程在泄洪消能的過(guò)程中水頭高,流量大,故高壩泄洪消能防護(hù)安全問(wèn)題十分突出。為了達(dá)到消能和防沖的目的,通常使用混凝土保護(hù)高壩下游處的河床,并在高壩下游合適處構(gòu)筑二道壩,形成消能防沖建筑物的一部分──水墊塘。由于高速水流及其產(chǎn)生的縫隙流的復(fù)雜性,高壩消力塘防護(hù)結(jié)構(gòu)的安全一直是水利工程安全領(lǐng)域研究的熱點(diǎn)問(wèn)題。其中對(duì)防護(hù)結(jié)構(gòu)體型進(jìn)行優(yōu)化,以達(dá)到增加抗失穩(wěn)能力的目的,是提高泄流結(jié)構(gòu)安全的方法之一。正是基于優(yōu)化設(shè)計(jì)出發(fā),相繼提出了平底板,反拱形底板,透水底板和帶鍵槽底板等型式。本文提出一種異形結(jié)構(gòu)水墊塘底板,即底板帶鍵槽加透水孔結(jié)構(gòu)型式,以向家壩水墊塘模型試驗(yàn)為背景,基于模型試驗(yàn)結(jié)果,利用多種信號(hào)處理技術(shù),研究了異形構(gòu)造底板縫隙處水流脈動(dòng)壓力特性,研究的主要內(nèi)容及研究成果為:(1)單板塊情況下增設(shè)鍵槽對(duì)底板脈動(dòng)壓力傳播特性的研究。結(jié)合向家壩水墊塘物理模型試驗(yàn)成果,分析了向家壩水墊塘底板增設(shè)鍵槽前后對(duì)底板上下表面以及垂直縫隙處脈動(dòng)壓力大小、分布規(guī)律,以及脈動(dòng)壓力的頻域特性和相關(guān)特性。結(jié)果表明:帶鍵槽底板可能產(chǎn)生的最大脈動(dòng)上舉力要比不帶鍵槽小;增設(shè)鍵槽后下表面空間和時(shí)間積分尺度增大,增大了渦旋的持有性,加強(qiáng)了板塊間的聯(lián)系,從紊流角度分析出板塊鍵槽的增設(shè)有利于結(jié)構(gòu)的穩(wěn)定性。(2)止水縫隙寬度對(duì)脈動(dòng)壓力傳播的影響研究。在保證底板與基巖縫隙不變的情況下,改變板塊間的止水縫隙,研究止水縫隙的改變對(duì)縫隙內(nèi)水流脈動(dòng)壓力的影響。結(jié)果表明:隨著止水縫隙的增大,產(chǎn)生的脈動(dòng)上舉力減小,有利于板塊的穩(wěn)定性;隨著止水縫隙的減小,主頻向低頻移動(dòng),優(yōu)勢(shì)頻帶變窄,集中在0.1Hz以下。(3)底板縫隙寬度對(duì)脈動(dòng)壓力傳播的影響。在保證底板與底板止水縫隙不變的情況下,改變底板與基巖縫隙,研究底板與基巖縫隙的改變對(duì)縫隙內(nèi)水流脈動(dòng)壓力的影響。結(jié)果表明:隨著縫隙厚度的增大,下表面測(cè)點(diǎn)均方差呈減小趨勢(shì);下表面測(cè)點(diǎn)的時(shí)間積分尺度也隨之增大,渦旋的持有率增加。(4)異形構(gòu)造底板穩(wěn)定性研究。在板塊上增設(shè)鍵槽并布置一定開(kāi)孔率的透水孔,對(duì)比分析異形構(gòu)造水墊塘底板與普通型式平底板水墊塘在高速水流的沖擊作用下所受上舉力特性等方面的異同點(diǎn)。結(jié)果表明:異形構(gòu)造底板下表面脈動(dòng)壓強(qiáng)系數(shù)要小于一般構(gòu)造底板下表面脈動(dòng)壓強(qiáng)系數(shù)。異形構(gòu)造底板能有效地降低水流脈動(dòng)能量,綜合了透水底板與帶鍵槽底板的優(yōu)勢(shì),明顯提高板塊穩(wěn)定性。
[Abstract]:The development capacity and construction scale of water energy in China are in the first place in the world. These projects have high water head and large discharge in the process of flood discharge and energy dissipation, so the safety problem of flood energy dissipation and protection of high dam is very prominent. In order to achieve the purpose of energy dissipation and erosion prevention, concrete is usually used to protect the riverbed downstream of the high dam, and to build two dams in the lower reaches of the high dam to form a part of the energy dissipation and scour prevention building, a part of the water cushion pond. Because of the complexity of high speed water flow and its crevice flow, the safety of the protective structure of high dam stilling pond has always been a hot topic in the field of water conservancy engineering safety. It is one of the methods to improve the safety of the leakage structure by optimizing the configuration of the protective structure to increase the ability of resisting instability. Based on the optimum design, the flat floor, the reverse arch floor, the permeable floor and the keyway floor are put forward one after another. In this paper, a kind of special shaped structure water cushion pond bottom plate with keyway and permeable hole structure is proposed. Based on the model test of Xiangjiaba water cushion pond, a variety of signal processing techniques are used. The characteristics of flow pulsation pressure at the crevice of irregular structural floor are studied. The main contents and results of the study are as follows: 1) in the case of single plate, the propagation characteristics of pulsating pressure on the bottom plate are studied by adding keyways. Combined with the physical model test results of Xiangjiaba water cushion pond, the fluctuating pressure magnitude, distribution law, frequency domain characteristic and correlation characteristic of fluctuating pressure on the upper and lower surface and vertical slot of Xiangjiaba water cushion pond floor before and after the addition of keyway are analyzed. The results show that the maximum pulsating lift force of the bottom plate with keyway is smaller than that without the keyway, and the space and time integral scale of the lower surface increases with the addition of the keyway, which increases the holding of vortex and strengthens the connection between plates. From the point of view of turbulence, the influence of the width of watertight gap on the propagation of fluctuating pressure is analyzed. The addition of plate keyway is beneficial to the stability of the structure. Under the condition that the gap between the bottom plate and the bedrock remains unchanged, the influence of the change of the gap on the pulsating pressure of the water flow in the gap is studied. The results show that the pulsating lifting force decreases with the increase of the sealing gap, which is beneficial to the stability of the plate, and with the decrease of the gap, the main frequency moves to the low frequency, and the dominant frequency band becomes narrower. The effect of gap width on pulsating pressure propagation is concentrated below 0.1Hz. Under the condition that the water stop gap between the bottom plate and the bottom plate is invariable, the influence of the change of the bottom plate and the bedrock gap on the flow pulsating pressure in the gap is studied. The results show that with the increase of gap thickness, the mean square deviation of measurement points on the lower surface tends to decrease, and the time integral scale of the measuring points on the lower surface also increases, and the holding ratio of vortex increases. 4) the stability of the irregular structural floor plate is studied. A keyway is added to the plate and a permeable hole with a certain opening rate is arranged. The similarities and differences between the bottom plate of a special shaped structure water cushion pond and the ordinary type of flat bottom water cushion pond under the impact of high speed water flow are compared and analyzed. The results show that the pulsating pressure coefficient is smaller than that of the general structural floor. The irregular structural floor can effectively reduce the flow pulsation energy, synthesizes the advantages of the permeable floor and the keyway floor, and obviously improves the stability of the plate.
【學(xué)位授予單位】：天津大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2014
【分類號(hào)】：TV135.2

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