本文選題：可降解土體 + 生化降解�。� 參考：《浙江大學》2015年碩士論文

【摘要】：可降解土體是指土體中的固相顆粒會在外部環(huán)境作用下會出現(xiàn)質(zhì)量損失、顆粒破碎的現(xiàn)象,引起孔隙率和顆粒組構(gòu)的變化,進而導(dǎo)致土體的土工特性及參數(shù)改變。常見的可降解土體有填埋場中高有機質(zhì)含量的城市固廢、土石壩中可侵蝕顆粒以及農(nóng)田中石灰性土壤等�？山到馔馏w的可降解特性導(dǎo)致其在多場耦合問題中變得尤為復(fù)雜。以填埋場為例,與普通土工構(gòu)筑物中的多場耦合相比,填埋場還需要考慮生化降解對多場耦合的影響,主要體現(xiàn)在兩方面：(1)由于固廢中可降解有機質(zhì)降解的影響,固廢的土工特性會隨著降解程度不同而變化；(2)由于降解產(chǎn)生的水、氣、液相溶質(zhì)等物質(zhì)也會作為源相參加到水氣運移和溶質(zhì)遷移等運動中�；诖�,本文在原有的多場耦合研究基礎(chǔ)上,重點研究了多組分氣體運移過程,以及降解過程對于模型參數(shù)的影響,主要內(nèi)容和研究成果包括： (1)基于填埋場中氣體涉及生化反應(yīng)的情況,本文建立了考慮多組分氣體運移的氣相運移控制方程,并基于前人對多場耦合中其他過程的研究,給出了可降解土體的生化降解-骨架變形-水氣運移-溶質(zhì)遷移(BCHM)多場耦合模型,并界定了模型中涉及的土工特性及參數(shù)； (2)基于已有的顆粒級配曲線描述函數(shù),本文從顆粒組構(gòu)以及孔隙比出發(fā),建立了固有滲透系數(shù)、相對液相/氣相滲透系數(shù)、體相擴散/液相溶質(zhì)擴散系數(shù)、努森擴散系數(shù)以及應(yīng)力應(yīng)變關(guān)系與顆粒級配曲線和孔隙比之間的關(guān)系,并對已有的土水特征曲線與顆粒級配曲線和孔隙比的關(guān)系進行了改進。通過改變顆粒級配曲線描述函數(shù)中的特征參數(shù)得到不同降解程度下的顆粒級配曲線,進而得到不同降解程度下的土工特性及參數(shù)。利用該預(yù)測模型,本文首先對不同降解模式下的各個土工參數(shù)的變化規(guī)律進行的分析。同時,以某填埋場為例,對不同齡期固廢的土水特征曲線、固有滲透系數(shù)、相對液相/氣相滲透系數(shù)進行了預(yù)測,并與試驗實測結(jié)果比對,結(jié)果顯示土水特征曲線、相對液相/氣相滲透系數(shù)的預(yù)測結(jié)果與試驗結(jié)果較為接近,固有滲透系數(shù)預(yù)測結(jié)果偏大于試驗結(jié)果。 (3)基于可降解土體多場耦合模型和可降解土體土工特性及參數(shù)預(yù)測方法,建立了可降解土體多場耦合模型,并給出了求解方法。以典型中國城市固廢為研究對象,采用可降解土體多場耦合模型,利用數(shù)值分析軟件OpenGeoSys和Matlab,分別研究了降解速率、土工特性及參數(shù)隨降解變化以及初始狀態(tài)對填埋體的影響。計算結(jié)果表明,生化降解速率越快,沉降發(fā)展、氣體逸出速率和滲濾液下滲速率越快；若不考慮降解過程對應(yīng)力應(yīng)變關(guān)系的影響,會導(dǎo)致預(yù)測的沉降量小,飽和度偏低；若不考慮降解對土水特征曲線的影響,會低估固廢的降解程度；若不考慮降解過程對固有滲透系數(shù)的影響,會低估固廢的飽和度。初始孔隙比越小,初始基質(zhì)吸力越小,固廢降解速率越快。 (4)為研究填埋場覆蓋層氣相污染物遷移規(guī)律,將本文多場耦合模型中的生化降解、骨架變形、孔隙水運移以及溶質(zhì)遷移等過程忽略,退化至多組分氣體運移模型。利用該模型分析了不同有效二元擴散系數(shù)、不同頂部邊界下達到穩(wěn)態(tài)時覆蓋層氣體組分分布。結(jié)果表明,穩(wěn)態(tài)下各組分氣體分布形式與有效氣體二元擴散系數(shù)和頂部邊界氣體組分密切相關(guān),對頂部邊界氣壓大小不敏感。為研究考慮固結(jié)下填埋場襯墊系統(tǒng)液相污染物遷移規(guī)律,將本文多場耦合模型中的生化降解和孔隙氣運移過程忽略,退化至骨架變形-孔隙水運移-溶質(zhì)遷移耦合模型。利用該模型的分析了不同上部荷載、不同上部水頭以及不同排水條件下污染物遷移規(guī)律。結(jié)果表明,液相污染物在襯墊系統(tǒng)中的遷移受到排水條件、頂部荷載、上部水頭等因素的影響,上部水頭越高、荷載越大,滲流路徑與遷移路徑一致時,污染物擊穿襯墊的時間越短。
[Abstract]:The degrading soil is the mass loss of solid particles in the soil and the fragmentation of the particles in the soil, which causes the change of the porosity and the structure of the particles, which leads to the change of the soil properties and the parameters of the soil. The degradability of the particles and the calcareous soil in the farmland. The degradability of the degradable soil causes it to become particularly complex in the multi field coupling problem. Taking the landfill as an example, compared with the multi field coupling in the common geotextile structure, the landfill also needs to consider the effects of biochemical degradation on the multi field coupling, mainly in two aspects: (1) due to the solid waste. The effect of degradation of degradable organic matter will change with the degradation degree of the solid waste. (2) due to the degradation of water, gas, liquid phase solute and other substances will also participate in the movement of water gas and solute migration as the source phase. Based on this, this paper focuses on the study of multi component gas on the basis of the existing multi field coupling research. The main contents and achievements of the migration process and the effects of degradation process on the model parameters are as follows:
(1) based on the biochemical reaction of gas in the landfill, a gas migration control equation with multi component gas migration is established in this paper. Based on the previous studies of other processes in the multi field coupling, the multi field coupling model of biodegradability skeleton deformation, water gas migration and solute migration (BCHM), is given and the model is defined. The geotechnical characteristics and parameters involved in the model;
(2) based on the existing granular distribution curve description function, the intrinsic permeability coefficient, relative liquid / gas permeability coefficient, bulk diffusion / liquid phase solute diffusion coefficient, the relationship between the sudson diffusion coefficient and the relationship between the stress strain relationship and the grain gradation curve and the pore ratio are established. The relationship between the water characteristic curve and the grain gradation curve and the porosity ratio is improved. By changing the characteristic parameters of the particle grading curve, the particle gradation curves under different degradation degrees are obtained, and then the geotextile characteristics and parameters under different degradation degrees are obtained. At the same time, taking a landfill as an example, the soil water characteristic curve, intrinsic permeability coefficient, relative liquid / gas permeability coefficient of solid waste at different ages were predicted, and compared with the experimental results, the results showed the characteristic curve of soil water and the prediction result of relative liquid / gas permeability coefficient. Compared with the test results, the prediction results of intrinsic permeability coefficient are larger than the experimental results.
(3) based on the multi field coupling model of degradable soil and the geotechnical characteristics of degradable soil soil and parameter prediction method, the multi field coupling model of degradable soil is established and the solution method is given. Taking the typical Chinese urban solid waste as the research object, the multi field coupling model of degradable soil is adopted, and the numerical analysis software OpenGeoSys and Matlab are used to study respectively. The results show that the faster the biodegradation rate, the development of the sedimentation, the faster the gas escape rate and the leachate infiltration rate, and the smaller the predicted settlement and saturation, if the degradation process is not considered. If we do not consider the effect of degradation on the soil water characteristic curve, the degradation degree of solid waste will be underestimated. If the influence of the degradation process on the intrinsic permeability coefficient is not considered, the saturation of solid waste will be underestimated. The smaller the initial void ratio, the smaller the initial matrix suction, the faster the degradation rate of solid waste.
(4) in order to study the migration law of the gas phase pollutants in the cover layer of the landfill, the biochemical degradation, the skeleton deformation, the pore water migration and the solute migration in the multi field coupling model are ignored, and the gas migration model is degenerated to the multicomponent gas migration model. The different effective two element diffusion coefficients are analyzed with the model, and the steady state overlying under the different top boundary is reached. The distribution of gas components in the cover shows that the gas distribution of each component in the steady state is closely related to the two element diffusion coefficient of the effective gas and the gas component at the top boundary, and is insensitive to the pressure of the top boundary pressure. The process of solution and pore gas migration is neglected and degenerated to the skeleton deformation pore water transport coupling model. The model is used to analyze the different upper load, the different upper head and the transport of pollutants under different drainage conditions. The results show that the migration of liquid pollutants in the liner system is subjected to drainage conditions, top load, The influence of the upper head and other factors is that the higher the upper water head and the greater the load, the shorter the seepage path and the migration path.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU43

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