本文關(guān)鍵詞： 砂礫覆蓋層 入滲 產(chǎn)流 蒸發(fā) 截留降雨 計(jì)算模型　出處：《中國(guó)科學(xué)院研究生院(教育部水土保持與生態(tài)環(huán)境研究中心)》2016年博士論文　論文類型：學(xué)位論文

【摘要】：砂礫層覆蓋于土壤表面,具有抑制土壤水分蒸發(fā)、抵抗土壤侵蝕的作用。砂田作為一種旱作覆蓋技術(shù),長(zhǎng)期應(yīng)用于我國(guó)西北干旱半干旱地區(qū),具有明顯調(diào)節(jié)農(nóng)田微環(huán)境的效果。相關(guān)研究具有理論與實(shí)用價(jià)值。降雨過(guò)程中,雨水穿過(guò)覆蓋層砂礫顆粒間的空隙下落至土壤表面并滲入土壤,其中部分雨水會(huì)被砂礫覆蓋層截留。本項(xiàng)研究根據(jù)顆粒物質(zhì)物理與力學(xué)、材料學(xué)和統(tǒng)計(jì)學(xué)理論,構(gòu)建了均一和非均一砂礫覆蓋層截留降雨量的計(jì)算模型。通過(guò)模擬降雨測(cè)定砂礫覆蓋層截留量的實(shí)驗(yàn)驗(yàn)證了模型的有效性。本研究取得的主要結(jié)果包括:(1)對(duì)于均一砂礫覆蓋層,可采用平均等效粒徑表征其顆粒特征。形狀、大小各異的顆粒構(gòu)成的群體,具有一定自相似特征,可以用分形維數(shù)來(lái)表征;如土粒質(zhì)地情況就可以細(xì)度分形維數(shù)來(lái)表征。但由于砂礫級(jí)配中往往存在某一粒級(jí)(較小的粒級(jí))范圍內(nèi)的質(zhì)量為零情況,零的對(duì)數(shù)不存在,以致不能確定其分形維數(shù),因而不能用分形維數(shù)表征覆蓋層砂礫的顆粒特征。(2)對(duì)于非均一砂礫,根據(jù)篩分析法的實(shí)驗(yàn)結(jié)果可求得非均一砂礫試樣的總體等效平均粒徑。確定了總體等效平均粒徑作為表征非均一粒徑砂礫試樣的技術(shù)指標(biāo)。(3)砂礫層持水量可分為動(dòng)態(tài)持水量和靜態(tài)持水量。在降雨過(guò)程中,覆蓋層中砂礫顆粒間空隙中流動(dòng)的水體,會(huì)因降雨不斷地流入覆蓋層而被更新;這部分只在降雨過(guò)程中存在于砂礫覆蓋層中的水量稱為動(dòng)態(tài)持水量。動(dòng)態(tài)持水過(guò)程比較復(fù)雜,試圖用模型定量描述其過(guò)程或計(jì)算其技術(shù)指標(biāo)比較困難。降雨停止后,砂礫覆蓋層中滯留的雨水經(jīng)過(guò)一段時(shí)間的排滴過(guò)程,當(dāng)不再有水體下流時(shí),被截持在砂礫覆蓋層中的水量稱為靜態(tài)持水量。靜態(tài)持水量是降雨后實(shí)際被截留在覆蓋層中雨水量。(4)根據(jù)對(duì)均一砂礫覆蓋層物理特性的分析,提出了確定均一砂礫覆蓋層的最大靜截留水量的計(jì)算方法。用模擬降雨實(shí)驗(yàn)檢測(cè)結(jié)果對(duì)模型計(jì)算結(jié)果進(jìn)行Paired-Samples T Test過(guò)程雙側(cè)檢驗(yàn),結(jié)果顯示,模型計(jì)算結(jié)果與實(shí)驗(yàn)檢測(cè)的結(jié)果差異無(wú)顯著性。(5)根據(jù)對(duì)非均一粒徑砂礫的級(jí)配特征的分析,提出了確定非均一粒徑砂礫覆蓋層截留雨水量的計(jì)算方法。將模型的計(jì)算結(jié)果與實(shí)驗(yàn)檢測(cè)結(jié)果進(jìn)行Paired-Samples T Test過(guò)程雙側(cè)檢驗(yàn),結(jié)果表明,模型計(jì)算和實(shí)驗(yàn)檢測(cè)的結(jié)果無(wú)顯著性差異。本項(xiàng)研究所確定的砂礫覆蓋層最大靜截留水量的計(jì)算模型,是建立在覆蓋層技術(shù)特征分析基礎(chǔ)上的半理論半經(jīng)驗(yàn)?zāi)Ｐ�。模型考慮了水與砂礫間的物理作用,較統(tǒng)計(jì)模型具有更廣泛的通用性和更明確的物理意義。研究結(jié)果可以用于定量預(yù)測(cè)砂礫覆蓋層截留降雨量的大小。
[Abstract]:Sand and gravel cover the soil surface, which can inhibit the evaporation of soil moisture and resist soil erosion. As a kind of dry mulching technology, sand field has been used in arid and semi-arid areas of northwest China for a long time. It has obvious effect of adjusting farmland microenvironment. Related research has theoretical and practical value. During rainfall, Rain Water falls to the soil surface through the gap between sand and gravel particles in the overburden and seeps into the soil. Some of Rain Water was intercepted by sand and gravel covering. This study was based on particle matter physics and mechanics, materials and statistical theory. The calculation model of rainfall interception in homogeneous and heterogeneous sand gravel cover is constructed. The validity of the model is verified by the experiment of simulated rainfall. The main results obtained in this study include: 1). For homogeneous gravel cover. The average equivalent particle size can be used to characterize the particle characteristics. The population with different shapes and sizes has some self-similar characteristics, which can be characterized by fractal dimension. For example, the grain texture can be characterized by fineness fractal dimension, but the logarithm of zero does not exist due to the fact that there is always zero mass in a certain grain-grade (smaller grain-grade) in the gradation of sand and gravel. As a result, the fractal dimension can not be determined, so the fractal dimension can not be used to characterize the grain characteristics of the covered sand gravel. According to the experimental results of sieve analysis method, the total equivalent average particle size of heterogeneous sand gravel samples can be obtained, and the total equivalent average particle size is determined as the technical index to characterize the heterogeneous gravelly samples. The water holding capacity of gravel layer can be divided into dynamic water holding capacity and static water holding capacity. The water body flowing in the gap between sand and gravel particles in the overburden will be renewed because of the continuous rainfall flowing into the overburden. This part is called dynamic water holding capacity which only exists in the sand gravel cover layer during rainfall. The dynamic water holding process is more complex. It is difficult to quantitatively describe the process or calculate the technical index by using the model. After the rainfall stops, Rain Water in the sand gravel overburden passes through a period of time to discharge the droplet, when there is no water body downflow. The water quantity intercepted in the sand gravel cover is called static water holding capacity. The static water holding capacity is the amount of rain water that is actually retained in the cover layer after rainfall. (4) based on the analysis of the physical characteristics of the uniform sand gravel cover layer, the static water holding capacity is called static water holding capacity. A calculation method for determining the maximum static retention water of homogeneous gravel overburden is proposed. Paired-Samples T is used to calculate the model result with the result of simulated rainfall experiment. Bilateral test of Test procedure. The results show that there is no significant difference between the calculated results of the model and the experimental results. 5) based on the analysis of the gradation characteristics of heterogeneous grained gravel. A calculation method for determining the amount of rainfall interception in non-uniform gravelly covering layer is proposed. The calculated results of the model and the experimental results are applied to Paired-Samples T. Bilateral test of Test procedure. The results show that there is no significant difference between the results of model calculation and experimental detection. It is a semi-theoretical semi-empirical model based on the analysis of the technical characteristics of the overburden. The model takes into account the physical interaction between water and sand and gravel. Compared with the statistical model, the results can be used to quantitatively predict the amount of retained rainfall in sandy gravel cover.
【學(xué)位授予單位】：中國(guó)科學(xué)院研究生院(教育部水土保持與生態(tài)環(huán)境研究中心)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2016
【分類號(hào)】：S157

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