本文選題：卵礫石粗糙床面 + 統(tǒng)計(jì)分析�。� 參考：《重慶交通大學(xué)》2017年碩士論文

【摘要】：粗糙床面在自然界中廣泛存在,床面粗糙特性與河流動(dòng)力學(xué)中的許多問(wèn)題(如泥沙起動(dòng)、河床阻力、推移質(zhì)運(yùn)動(dòng)等)密切相關(guān),但床面粗糙特性的科學(xué)量化一直是河流動(dòng)力學(xué)的難點(diǎn),也是目前尚未有效解決而又充滿(mǎn)挑戰(zhàn)的課題。本文在對(duì)天然卵礫石床面進(jìn)行深入調(diào)查的基礎(chǔ)上將其分類(lèi)概化,基于床面激光掃描試驗(yàn)資料,應(yīng)用統(tǒng)計(jì)分析方法和分形幾何理論開(kāi)展人工鋪制散疊型卵礫石床面粗糙特性研究。取得如下主要研究成果:(1)卵礫石床面高程的中數(shù)、眾數(shù)約等于平均高程;相對(duì)高程頻率分布呈負(fù)偏態(tài)、高狹峰,其負(fù)值跨度區(qū)遠(yuǎn)大于正值跨度區(qū)。(2)均勻顆粒床面高程的標(biāo)準(zhǔn)差隨粒徑的增大而增大,可作為均勻顆粒床面粗糙特性的優(yōu)良量化指標(biāo)。(3)卵礫石床面的變異特征與球狀模型最為接近,球狀模型可作為卵礫石床面變異性分析的最優(yōu)模型。(4)卵礫石床面橫縱向剖面輪廓平均變異函數(shù)與床面特征方向平均變異函數(shù)的基臺(tái)值和塊金常數(shù)基本相同,而變程卻存在較大差異。(5)剖面輪廓和粗糙床面的分形尺度區(qū)寬度與床面顆粒中值粒徑d50有關(guān),上臨界尺度可分別取為(0.5~1.5)d50和(0.8~2.1)d50,平均寬分別約為d50和1.5d50。(6)粗糙床面分形維數(shù)與覆蓋基準(zhǔn)面位置有關(guān),當(dāng)覆蓋基準(zhǔn)面取平均床面時(shí),分形維數(shù)取得真實(shí)值,且隨床面變化較為敏感,可有效量化和區(qū)分床面粗糙特征。(7)不同方向剖面輪廓的分形維數(shù)差異較大,剖面輪廓具有不同程度的各向異性;剖面輪廓分形維數(shù)的頻率分布具有雙峰特征。(8)均勻礫石顆粒床面粒徑越大,床面高程標(biāo)準(zhǔn)差越大,偏度越小,分形維數(shù)越小。(9)非均勻卵礫石顆粒床面級(jí)配組成相同時(shí),中值粒徑越大,分形維數(shù)越小;中值粒徑相同時(shí),顆粒組成越不均勻,分形維數(shù)越大;床面高程極差、標(biāo)準(zhǔn)差、偏度(絕對(duì)值)和峰度越大,分形維數(shù)越小。(10)床面整體分維隨剖面輪廓分維的增大而增大,數(shù)值上略大于局部分維;粗糙床面分維的變異性明顯小于剖面輪廓分維,兩者異性指數(shù)相差一個(gè)數(shù)量級(jí),粗糙床面分維具有良好的穩(wěn)定性,可作為粗糙床面特征的綜合量化參數(shù)。
[Abstract]:Rough bed surface exists widely in nature. The roughness of bed surface is closely related to many problems in river dynamics (such as sediment starting, bed resistance, bed load movement, etc.). However, the scientific quantification of bed roughness has been a difficult point in river dynamics, which has not yet been effectively solved and is full of challenges. In this paper, the natural gravel bed surface is classified and generalized on the basis of in-depth investigation. Based on the laser scanning test data of the bed surface, the statistical analysis method and the fractal geometry theory are used to study the roughness characteristics of the artificial scattered gravel bed surface. The main research results are as follows: (1) the median height of the gravel bed surface, the mode of which is equal to the average height, the relative elevation frequency distribution is negative skewed, the high peak is high, The standard deviation of the height of uniform particle bed increases with the increase of particle size. It can be used as an excellent quantitative index for the roughness characteristics of homogeneous granular bed surface. The variation characteristics of gravel bed surface are most close to the spherical model. The spherical model can be used as the best model for the analysis of the variation of the gravel bed surface. 4) the average variation function of the profile of the cross and longitudinal profile of the gravel bed surface is basically the same as the base table value and the block gold constant of the average variation function of the characteristic direction of the bed surface. However, there is a great difference between the variation range and the profile of the profile and the width of the fractal scale area of the rough bed surface, which is related to the median particle size d _ (50) of the bed surface. The upper critical scale can be taken as 0.5U / 1.5 / d50 and 0.82.1d50, respectively. The average width is about d50 and 1.5d50.60) the fractal dimension of rough bed surface is related to the position of covering datum level. When the coverage datum is taken as average bed surface, the fractal dimension can get real value, and it is sensitive to the change of bed surface. The fractal dimension of profile in different directions is different, and the profile has anisotropy in different degree. The frequency distribution of fractal dimension of profile has bimodal feature. (8) the larger the particle size of uniform gravel bed, the greater the standard deviation of bed height, the smaller the deviation, the smaller the fractal dimension, and the smaller the fractal dimension. The larger the median particle size is, the smaller the fractal dimension is; the more uneven the particle composition is, the larger the fractal dimension is when the median particle size is the same, the greater the height of bed, the standard deviation, the deviation (absolute value) and the kurtosis, The smaller the fractal dimension is, the larger the overall fractal dimension of bed surface is with the increase of profile fractal dimension, and the greater the numerical value is, the greater the variation of fractal dimension of rough bed surface is than the fractal dimension of profile, and the difference of heterogeneity index between them is one order of magnitude, and the variation of fractal dimension of rough bed surface is obviously smaller than that of profile fractal dimension. The fractal dimension of rough bed surface has good stability and can be used as a comprehensive quantization parameter of rough bed surface feature.
【學(xué)位授予單位】：重慶交通大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：U617;TV882.2

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