本文選題：核廢料緩沖回填材料 + 膨潤(rùn)土��； 參考：《上海交通大學(xué)》2015年博士論文

【摘要】：深層地質(zhì)處置是國(guó)際上普遍接受和認(rèn)可的高放射性核廢料的最終處置方案。膨潤(rùn)土因具有高吸水膨脹性、低滲透性和強(qiáng)核素吸附性等優(yōu)點(diǎn)被選作深層地質(zhì)處置系統(tǒng)中緩沖回填材料的主料。在核廢料處置庫(kù)的運(yùn)行過(guò)程中,圍巖周圍的地下水滲入緩沖回填材料中對(duì)膨潤(rùn)土的膨脹特性產(chǎn)生影響。如何準(zhǔn)確計(jì)算和預(yù)測(cè)膨潤(rùn)土在地下水溶液中的膨脹特性和膨脹性衰減規(guī)律是亟待解決的關(guān)鍵問(wèn)題。本文通過(guò)室內(nèi)膨潤(rùn)土的膨脹試驗(yàn)和理化測(cè)試,結(jié)合理論分析和數(shù)值模擬,研究了膨潤(rùn)土在地下水溶液中的膨脹特性,提出了膨潤(rùn)土在鹽溶液中的膨脹模型和膨脹性的計(jì)算方法,分析了膨潤(rùn)土膨脹性衰減機(jī)理,模擬了膨潤(rùn)土在核廢料處置庫(kù)中的膨脹特性和衰減規(guī)律,為核廢料深層地質(zhì)處置庫(kù)的建設(shè)和安全運(yùn)行提供科學(xué)依據(jù)。主要的研究?jī)?nèi)容如下:(1)采用N2吸附法測(cè)量了膨潤(rùn)土的表面分維。采用N2吸附法測(cè)量壓實(shí)膨潤(rùn)土在蒸餾水和不同濃度的Na Cl溶液中浸泡后的表面分維,膨潤(rùn)土壓實(shí)試樣的表面分維與膨潤(rùn)土粉末試樣的表面分維相當(dāng),鹽溶液對(duì)膨潤(rùn)土的表面分維的影響很小。(2)采用固結(jié)儀測(cè)量了商用膨潤(rùn)土壓實(shí)試樣在蒸餾水和NaCl溶液中的膨脹變形和膨脹力。膨潤(rùn)土的膨脹特性與豎向應(yīng)力、試樣的干密度和鹽溶液的濃度密切相關(guān)。在nacl溶液中,滲透吸力抑制了膨潤(rùn)土的膨脹特性,鹽溶液濃度越大,膨脹越小。(3)建立了膨潤(rùn)土膨脹的分形模型。基于膨潤(rùn)土吸水膨脹過(guò)程的表面吸附作用,根據(jù)膨潤(rùn)土表面的分形模型,建立了膨脹吸水體積的表達(dá)式,導(dǎo)出膨脹變形和膨脹力的理論公式。在膨潤(rùn)土的滲透膨脹階段,結(jié)合雙電層理論給出分形模型中的蒙脫石膨脹系數(shù)k,完善了分形模型。在鹽溶液中,基于膨潤(rùn)土表面的分形模型,推導(dǎo)出由孔隙水滲透吸力引起的有效應(yīng)力,提出了鹽溶液中的膨脹變形理論,并得到了鹽溶液中膨脹變形數(shù)據(jù)的驗(yàn)證。(4)揭示了gmz01膨潤(rùn)土在氯鹽溶液(nacl、cacl2、mgcl2)和naoh溶液中膨脹性衰減機(jī)理。膨潤(rùn)土與氯鹽溶液混合后,陽(yáng)離子交換是主要的化學(xué)反應(yīng)過(guò)程,ca2+和mg2+與na基蒙脫石中的na+反應(yīng)生成膨脹性較低的ca基或mg基蒙脫石,引起膨脹性衰減。與naoh混合后,高堿性溶液對(duì)蒙脫石有強(qiáng)烈的溶蝕作用,蒙脫石發(fā)生溶解生成非膨脹性礦物,導(dǎo)致膨脹性衰減�；谂驖�(rùn)土膨脹性衰減機(jī)理,采用膨脹變形的分形模型預(yù)測(cè)了滲透吸力、離子交換反應(yīng)和蒙脫石含量引起的膨脹衰減規(guī)律。(5)基于核廢料處置庫(kù)中緩沖回填材料的thmc四場(chǎng)耦合作用,建立膨潤(rùn)土的多場(chǎng)耦合方程。采用comsolmultiphysics軟件和Phreeqc軟件,模擬了核廢料處置庫(kù)中膨潤(rùn)土的飽和膨脹過(guò)程和長(zhǎng)時(shí)間多場(chǎng)耦合作用下的膨脹性衰減過(guò)程。分析了膨潤(rùn)土吸水膨脹隨時(shí)間的演化規(guī)律,計(jì)算了隨時(shí)間延長(zhǎng)飽和膨潤(rùn)土中滲透吸力、蒙脫石含量、膨脹系數(shù)K、有效應(yīng)力和膨脹力的衰減程度,給出膨潤(rùn)土膨脹性衰減的定量評(píng)估方法。
[Abstract]:Deep geological disposal is the ultimate disposal scheme of high radioactive nuclear waste widely accepted and accepted internationally. Bentonite is selected as the main material of buffer backfill material in deep geological disposal system because of its advantages of high water absorption, low permeability and strong nuclide absorbability. The expansion characteristics of bentonite are affected by the infiltration of water into the cushioning backfill material. How to accurately calculate and predict the swelling characteristics and the law of expansion attenuation in the solution of bentonite is the key problem to be solved. This paper studies the expansion test and physical and chemical test of bentonite in the laboratory, and studies the theoretical and numerical simulation. The expansion characteristics of bentonite in the groundwater solution, the expansion model of bentonite in salt solution and the calculation method of expansibility are put forward. The expansion attenuation mechanism of bentonite is analyzed, the expansion characteristic and attenuation law of bentonite in the nuclear waste disposal repository are simulated, which is for the construction and safe operation of the deep geological disposal repository of nuclear waste material. The main research contents are as follows: (1) the surface fractal dimension of bentonite is measured by N2 adsorption method. The surface fractal dimension of compacted bentonite in distilled water and Na Cl solution of different concentration is measured by N2 adsorption method. The surface fractal dimension of bentonite compacted sample is equivalent to the surface fractal dimension of bentonite powder sample, and the salt solution is the same The effect of the surface fractal dimension of bentonite is very small. (2) the expansion deformation and expansion force of commercial bentonite compacted samples in distilled water and NaCl solution are measured by a consolidation instrument. The expansion characteristics and vertical stress of bentonite are closely related to the dry density of the specimen and the concentration of salt solution. In the NaCl solution, the osmosis suction inhibits the expansion of bentonite. Characteristics, the greater the concentration of salt solution, the smaller the expansion. (3) a fractal model of swelling of bentonite was established. Based on the surface adsorption of bentonite, the expression of expansion water absorption volume was established according to the fractal model of bentonite surface, and the theoretical formula of expansion deformation and swelling force was derived. Based on the double layer theory, the expansion coefficient K of the montmorillonite in the fractal model is given, and the fractal model is perfected. In salt solution, based on the fractal model of the bentonite surface, the effective stress caused by the permeation suction of pore water is derived. The theory of expansion deformation in salt solution is put forward, and the data of expansion and deformation in salt solution are verified. (4) The expansion attenuation mechanism of gmz01 bentonite in chloride solution (NaCl, CaCl2, MgCl2) and NaOH solution was shown. After the mixture of bentonite and chloride solution, the cation exchange was the main chemical reaction process. The na+ reaction in ca2+ and mg2+ and Na Based Montmorillonite produced a lower expansive CA based or Mg base montmorillonite, causing expansibility attenuation. After mixing with NaOH, it was mixed with NaOH. The high alkaline solution has a strong corrosion effect on montmorillonite. Montmorillonite dissolves to produce non expansive minerals and causes expansion attenuation. Based on the expansion attenuation mechanism of bentonite, the expansion and deformation model is used to predict the expansion attenuation law caused by the permeation suction, ion exchange reaction and montmorillonite content. (5) based on the nuclear waste place The multi field coupling equation of bentonite is established by THMC four field coupling effect of buffer backfill material in the warehouse. The saturated expansion process of bentonite in the nuclear waste disposal repository and the expansion attenuation pass under long time multi field coupling are simulated by comsolmultiphysics software and Phreeqc software. The water swelling of bentonite is analyzed with time. The law of evolution is used to calculate the permeation suction, the content of montmorillonite, the expansion coefficient K, the effective stress and the attenuation of the expansion force, and the quantitative evaluation method of swelling attenuation of bentonite is given.

【學(xué)位授予單位】：上海交通大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU443

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本文編號(hào)：1893710