【摘要】：巖土介質(zhì)是自然界中廣泛存在的非均勻多孔介質(zhì)。固態(tài)顆粒的不同形狀大小、孔隙的空間排布形式以及土體內(nèi)部復(fù)雜組分等因素構(gòu)成了巖土介質(zhì)典型的非均質(zhì)特性。與其相關(guān)的滲流以及物質(zhì)運(yùn)移現(xiàn)象是巖土工程領(lǐng)域研究的基礎(chǔ)課題之一。目前主要研究手段是從宏觀體入手,采用唯象方法。但宏觀單元表現(xiàn)出的性質(zhì)本質(zhì)上是微觀尺度物理化學(xué)現(xiàn)象的反映。以該思路出發(fā),應(yīng)從微觀角度充分考慮孔隙特征,并將孔隙內(nèi)發(fā)生的各種物理化學(xué)過(guò)程與宏觀體的滲流以及物質(zhì)運(yùn)移聯(lián)系起來(lái)。這樣將更為本質(zhì)地對(duì)這一課題進(jìn)行研究。 基于以上考慮,本文借助雙尺度漸進(jìn)展開方法,針對(duì)多孔介質(zhì)基本物理量彎曲度、土體內(nèi)滲流現(xiàn)象以及物質(zhì)運(yùn)移現(xiàn)象,開展了從微觀到宏觀的理論展開分析及數(shù)值計(jì)算工作,并得到下列成果： (1)分別采用幾何路線方法和雙尺度漸進(jìn)展開方法,針對(duì)圓形顆粒及方形顆粒多孔介質(zhì),建立了相應(yīng)的彎曲度-孔隙率模型關(guān)系。提出多孔介質(zhì)彎曲度與孔隙率的自然對(duì)數(shù)成線性關(guān)系。不同介質(zhì)彎曲度模型間的差異主要體現(xiàn)在自然對(duì)數(shù)前的特征系數(shù)。針對(duì)不同顆粒形狀的多孔介質(zhì),計(jì)算得出了特征系數(shù)的下限值。所求模型與玻璃顆粒的多孔介質(zhì)實(shí)測(cè)值對(duì)比,發(fā)現(xiàn)有著較好的吻合程度,驗(yàn)證了本文方法的合理性。對(duì)于自然土體,通過(guò)實(shí)際情況分析了物理吸附(吸濕水)、化學(xué)吸附以及顆粒排列三個(gè)對(duì)土體彎曲度影響比較大的因素并進(jìn)行了計(jì)算,得到了土體中彎曲度的影響因素,并定量得到了不同影響因素下的模型。 (2)基于Navier-Stokes方程,得到多孔介質(zhì)滲透率的雙尺度計(jì)算解答。計(jì)算結(jié)果顯示,對(duì)于滲透率的計(jì)算,排列形式幾乎沒(méi)有影響,而顆粒形狀、顆粒大小以及孔隙率卻存在著較為顯著的影響,顆粒大小、孔隙率與滲透率之間是正相關(guān)的。同時(shí)將該解答應(yīng)用于砂土、高嶺土、伊利土以及海洋粘土滲透率預(yù)測(cè)計(jì)算中。 (3)通過(guò)對(duì)彌散方程的尺度擴(kuò)展,得到了強(qiáng)擴(kuò)散模型、弱擴(kuò)散模型、彌散模型、均質(zhì)化不適用四種模型以及不同模型間的界限閾值。同時(shí)得到有效擴(kuò)散系數(shù)的雙尺度計(jì)算解答。計(jì)算顯示,對(duì)于有效擴(kuò)散系數(shù)的計(jì)算,顆粒大小以及排列形式幾乎沒(méi)有影響,而顆粒形狀與孔隙率卻存在著較為顯著的影響。另一方面,可將該解答應(yīng)用于土體的有效擴(kuò)散系數(shù)預(yù)測(cè)計(jì)算中。與滲透率的雙尺度解答對(duì)比發(fā)現(xiàn),在滲流與擴(kuò)散的參量影響因素中,相同的是孔隙率對(duì)于滲透率及有效擴(kuò)散系數(shù)的影響都為正向的,顆粒排列都沒(méi)有影響,所不同的是,顆粒大小對(duì)滲透率的結(jié)果有影響,而與有效擴(kuò)散系數(shù)最終值無(wú)關(guān)。 (4)彎曲度隨孔隙率的變化而變化,但現(xiàn)有的一些滲流模型中將彎曲度視為一定值,這種處理方式是有失妥當(dāng)?shù)摹Ｍㄟ^(guò)本文建立的彎曲度-孔隙率關(guān)系式,對(duì)Bruschke and Advani理論模型進(jìn)行了修正,修正后的模型與修正前相比,與滲透率雙尺度計(jì)算解有著更為良好的吻合程度。 (5)通過(guò)對(duì)有效擴(kuò)散系數(shù)與彎曲度間關(guān)系的理論推導(dǎo)以及本文建立的彎曲度-孔隙率模型,提出了有效擴(kuò)散系數(shù)與分子擴(kuò)散系數(shù)比值的上限。該上限值存在的本質(zhì)原因是不同形狀顆粒的彎曲度存在著最小值。所得模型能較好的包含非飽和土體中的相關(guān)實(shí)測(cè)數(shù)據(jù)。
[Abstract]:Geotechnical medium is a widely distributed heterogeneous porous medium in nature. The different shapes and sizes of solid particles, the spatial arrangement of pores, and the complex components in the soil form the typical heterogeneity of the rock and soil medium. The related seepage and material migration are the basic subjects in the field of geotechnical engineering. At present, the main research means is to start with macroscopic bodies and adopt phenomenological methods. However, the nature of the macro unit is essentially a reflection of the microscopic physical and chemical phenomena. In this way, the pore characteristics should be fully considered from the microscopic point of view, and the various physical and chemical processes occurring in the pores and the percolation and objects of the macroscopic bodies should be taken into consideration. Qualitative migration is linked, so that this subject will be studied in a more essential way.
Based on the above considerations, with the help of the two scale progressive expansion method, the theoretical analysis and numerical calculation are carried out from microcosmic to macroscopic, and the following results are obtained in view of the basic physical quantity bending of porous media, the phenomenon of seepage in the soil and the phenomenon of material migration.
(1) the relationship between the bending degree and porosity model of the circular particles and the square particle porous media is established by using the geometric route method and the double scale progressive expansion method. The linear relationship between the natural logarithm of the porosity and the porosity of the porous medium is put forward. The difference between the bending models of different medium is mainly reflected before the natural logarithm. The lower limit of the characteristic coefficient is calculated for porous media with different particle shapes. The model is compared with the measured value of the porous media of the glass particles. It is found that there is a good degree of anastomosis and the rationality of the method is verified. Physical adsorption (hygroscopic water) and chemistry are analyzed for natural soil. Three factors which have large influence on the soil bending degree are calculated by adsorption and particle arrangement, and the influence factors of the bending degree are obtained, and the models under different influence factors are obtained.
(2) a double scale solution of porous medium permeability is obtained based on the Navier-Stokes equation. The calculation results show that there is little influence on the arrangement form for the calculation of permeability, but the particle size, particle size and porosity have a more significant influence. The particle size, porosity and permeability are positively correlated. The solution is applied to the prediction of sand, kaolin, illite and marine clay permeability.
(3) by extending the dispersion equation, the strong diffusion model, the weak diffusion model, the dispersion model, the homogenization of the four models and the threshold values between different models are not applied. The effective diffusion coefficient is obtained by the double scale calculation solution. The calculation shows that the size and arrangement of the effective diffusion coefficients are almost the size and the arrangement form. On the other hand, the solution can be applied to the prediction of effective diffusion coefficient of soil. In comparison with the double resolution of permeability, it is found that the same is the porosity for permeability and effective diffusion coefficient in the factors affecting the permeability and diffusion parameters. All the effects are positive. The particle size has no effect on the particle size, and the size of the particles has an effect on the results of the permeability, but it has nothing to do with the final value of the effective diffusion coefficient.
(4) the bending degree varies with the change of porosity, but in some existing seepage models, the bending degree is considered as a certain value. This method is inappropriate. The Bruschke and Advani theoretical model is corrected by the formula of the curvature porosity and porosity established in this paper. The modified model is compared with the correction before the correction, and the double scale of the permeability is compared with the permeability. The calculated solution has a better degree of anastomosis.
(5) through the theoretical deduction of the relationship between the effective diffusion coefficient and the bending degree and the model of the curvature porosity established in this paper, the upper limit of the ratio of the effective diffusion coefficient to the molecular diffusion coefficient is put forward. The essential reason for the existence of the upper limit is that the bending degree of different shapes of particles has the minimum value. And the relevant measured data in the soil.
【學(xué)位授予單位】：浙江大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2014
【分類號(hào)】：TU43;O357.3

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