發(fā)布時(shí)間：2018-10-14 08:56

【摘要】：推移質(zhì)運(yùn)動(dòng)規(guī)律的研究是泥沙運(yùn)動(dòng)力學(xué)及河流動(dòng)力學(xué)的基本課題之一。認(rèn)識(shí)和掌握山區(qū)河流卵石推移質(zhì)的運(yùn)動(dòng)規(guī)律對(duì)水利工程的安全以及預(yù)測(cè)河道演變趨勢(shì)意義重大。推移質(zhì)的運(yùn)動(dòng)形式一般可分為滾動(dòng)、滑動(dòng)和躍移。一般認(rèn)為躍移是推移質(zhì)運(yùn)動(dòng)的主要形式。然而，當(dāng)水流強(qiáng)度較低時(shí)，顆粒運(yùn)動(dòng)形式以滾動(dòng)為主；即使躍移顆粒，通常在躍起之前需要先滾動(dòng)一段距離。因此，有必要進(jìn)行泥沙顆粒滾動(dòng)機(jī)理的研究。 本文針對(duì)滾動(dòng)型推移質(zhì)，從泥沙顆粒典型受力出發(fā)，建立了其運(yùn)動(dòng)的力學(xué)模型。該力學(xué)模型引入相對(duì)暴露度，考慮了泥沙位置對(duì)其運(yùn)動(dòng)的影響；將單步滾動(dòng)步劃分為接觸步和自由步，具體脫離點(diǎn)位置取決于其相對(duì)暴露度和水流強(qiáng)度。本文首先分析了泥沙的起動(dòng)，在推導(dǎo)起動(dòng)流速時(shí)，考慮了流速的脈動(dòng)和泥沙顆粒的相對(duì)暴露度這兩個(gè)隨機(jī)變量，，經(jīng)推導(dǎo)得到了單顆粒泥沙的起動(dòng)概率和考慮起動(dòng)概率的泥沙起動(dòng)流速公式，且用實(shí)測(cè)資料進(jìn)行了驗(yàn)證。接著通過(guò)數(shù)值求解和回歸分析的手段，求解了滾動(dòng)推移質(zhì)運(yùn)動(dòng)的力學(xué)模型，求出單步運(yùn)動(dòng)參數(shù)如單步步長(zhǎng)和單步運(yùn)動(dòng)時(shí)間等的數(shù)學(xué)表達(dá)式。最終利用愛(ài)因斯坦的思想，修正了其中的沖刷概率和單步步長(zhǎng)，結(jié)合概率論推導(dǎo)出輸沙率表達(dá)式，并用實(shí)測(cè)卵石輸沙率資料進(jìn)行了驗(yàn)證，表明其適用于低水流范圍內(nèi)的推移質(zhì)運(yùn)動(dòng)，且與韓其為低輸沙率公式相比，適用的水流范圍更廣。
[Abstract]:The study of bed load motion is one of the basic subjects of sediment movement mechanics and river dynamics. It is of great significance to understand and master the movement law of pebble bed load in mountain rivers for the safety of water conservancy projects and to predict the trend of river channel evolution. Bedload motion can generally be divided into rolling, sliding and jumping. It is generally considered that jumping is the main form of bed load movement. However, when the flow intensity is low, the motion of particles is mainly in the form of rolling, and even if the particles leap, they usually need to roll a distance before jumping up. Therefore, it is necessary to study the rolling mechanism of sediment particles. In this paper, according to the rolling bed load and the typical force of sediment particles, a mechanical model of its motion is established. In this model, the relative exposure degree is introduced, and the influence of sediment position on its motion is considered, and the single step rolling step is divided into contact step and free step, and the location of the breakaway point depends on the relative exposure degree and the flow intensity. In this paper, the incipient velocity of sediment is analyzed, and the fluctuation of velocity and the relative exposure of sediment particles are taken into account in the derivation of the incipient velocity. The incipient probability of single sediment and the formula of sediment incipient velocity considering the starting probability are derived and verified by the measured data. Then by means of numerical solution and regression analysis, the mechanical model of rolling bedload motion is solved, and the mathematical expressions of single step motion parameters such as single step length and single step motion time are obtained. Finally, by using Einstein's thought, the erosion probability and the single step length are corrected, and the expression of sediment transport rate is deduced with probability theory, and verified by the measured data of cobble sediment transport rate. It shows that it is suitable for the bedload movement in the range of low water flow, and compared with the formula of low sediment transport rate in Korea, the applicable range of flow is wider.
【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(lèi)號(hào)】：TV142.2

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