本文選題：地下放大試驗(yàn)　切入點(diǎn)：砌塊接縫　出處：《蘭州大學(xué)》2015年碩士論文　論文類型：學(xué)位論文

【摘要】：目前,世界部分國家已從室內(nèi)試驗(yàn)轉(zhuǎn)移至地下放大試驗(yàn)研究。一般認(rèn)為,堆砌法比較適用于處置罐體所在的污染緩沖區(qū)。采用堆砌法將緩沖回填砌塊材料進(jìn)行拼接,會(huì)產(chǎn)生砌塊接縫。砌塊接縫作為緩沖回填材料的“水力缺陷”,其防滲性能成為地質(zhì)處置工程中的薄弱部位,其接縫處的膨脹自愈能力及防滲性能已成為首要關(guān)注的核心問題。本文選用高廟子膨潤土和石英砂作為緩沖回填材料,用靜立壓實(shí)法將混合物制成干密度1.7g/cm3和摻砂量30%的完整圓餅狀和圓餅中間分割狀試樣。設(shè)置砌縫寬度為2mm,并用膨潤土粉末、塑限狀態(tài)膨潤土以及粒徑為0.25-0.5mm且干密度為1.8g/cm3的膨潤土顆粒與膨潤土粉末按30%,50%,70%和90%不同比例混合分別作為不同接縫處的材料,以完整試樣作為對(duì)比參照,利用柔性壁滲透儀對(duì)不同接縫處理形式的壓實(shí)砌塊進(jìn)行滲透試驗(yàn),并測(cè)量試樣愈合后的導(dǎo)熱性能及微觀結(jié)構(gòu)的變化,研究不同接縫處理形式的膨脹自愈能力和防滲性能。研究表明：以完整試樣作對(duì)比,各接縫處理形式的水力傳導(dǎo)系數(shù)的范圍為(2.51-4.94)×10-10 cm/s,其中顆粒率為70%的接縫形式的滲透性較低,且其愈合后接縫處微觀結(jié)構(gòu)的顆粒排列較為緊密,孔隙較小且分布密集,愈合程度較好；各接縫處理形式接縫處的平均熱傳導(dǎo)系數(shù)范圍為1.43-1.63W/(m·k),其中顆粒率為70%的砌縫的平均熱傳導(dǎo)系數(shù)為最大,其導(dǎo)熱性能較好。除干粉和膏狀的其他接縫形式沿著接縫方向的熱傳導(dǎo)系數(shù)的方差相差不大,且方差數(shù)值較小,認(rèn)為這幾種接縫處理形式的導(dǎo)熱性能較為穩(wěn)定。結(jié)合以上試驗(yàn)研究,選取顆粒率為70%的砌縫為最佳接縫處理形式。砌塊接縫愈合機(jī)理研究表明,一方面,膨潤土材料遇水膨脹后,會(huì)形成一層薄膜包裹在石英砂顆粒表面,并逐漸填充石英砂顆粒之間的孔隙；另一方面接縫處的膨潤土材料與膨潤土砌塊共同遇水膨脹,在此作用下,膨潤土顆粒之間的大孔隙逐漸被填充形成許多小孔隙,并在較大的圍壓作用下,接縫與膨潤土砌塊之間結(jié)構(gòu)進(jìn)行重組,原有的接縫結(jié)構(gòu)面逐漸消失,接縫處的密度與接縫附近的密度逐漸趨于一致,即接縫愈合。
[Abstract]:At present, some countries in the world have transferred from indoor test to underground amplification test. It is generally considered that the stacking method is more suitable for disposal of the polluted buffer zone where the tank body is located, and the cushioning backfill block material is jointed by the stacking method. Block joints will be produced. Block joints are "hydraulic defects" of cushioning backfill materials, and their impermeability becomes a weak part in geological disposal projects. The expansion self-healing capacity and impermeability of the joints have become the core issues of primary concern. In this paper, the high temple bentonite and quartz sand are used as buffer backfill materials. The mixture was prepared by static compaction method into complete round cake and round cake with dry density of 1.7 g / cm ~ 3 and sand content of 30%. The width of joint was set at 2 mm and bentonite powder was used. The plastic-limited bentonite and bentonite particles with a dry density of 1.8 g / cm ~ 3 with a diameter of 0.25-0.5 mm and a dry density of 1.8 g / cm ~ 3 were mixed with bentonite powder at different proportions of 30% and 50% and 90% respectively as materials for different joints. The permeation tests of compacted blocks with different joint types were carried out by using a flexible wall permeation apparatus, and the thermal conductivity and microstructure of the specimens after healing were measured. The expansion self-healing ability and impermeability of different joint treatment forms are studied. The results show that the hydraulic conductivity coefficient of each joint treatment form is in the range of 2.51-4.94) 脳 10 ~ (-10) cm / s, and the permeability of the joint form with particle ratio of 70% is lower than that of the whole joint treatment, and the hydraulic conductivity coefficient of each joint treatment form is in the range of 2.51-4.94 脳 10 ~ (-10) cm / s. The microstructure of the joint after healing is closely arranged, the porosity is small and the distribution is dense, and the degree of healing is better. The average heat conduction coefficient of each joint is 1.43-1.63W / m 路kg, and the average thermal conductivity of the joint with particle ratio of 70% is the largest. Its thermal conductivity is better. Except for dry powder and other joint forms, the variance of thermal conductivity along the joint direction is not different, and the variance value is small. It is considered that the thermal conductivity of these joint treatment forms is relatively stable. In combination with the above experimental study, the best joint treatment form is selected with particle ratio of 70%. The research on the mechanism of block joint healing shows that, on the one hand, When the bentonite material is swelled by water, it will form a film wrapped on the surface of quartz sand grain and gradually fill the pores between quartz sand particles. On the other hand, the bentonite material at the joint and the bentonite block will meet water expansion together, and under this action, The macropores between bentonite particles are gradually filled into many small pores, and under the action of larger confining pressure, the structure between the joint and the bentonite block is reorganized, and the original joint structure surface gradually disappears. The density of the joint tends to be consistent with the density near the joint, that is, joint healing.
【學(xué)位授予單位】：蘭州大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU522.3

【參考文獻(xiàn)】

相關(guān)期刊論文 前1條

1 劉月妙,溫志堅(jiān);用于高放射性廢物深地質(zhì)處置的粘土材料研究[J];礦物巖石;2003年04期

，

本文編號(hào)：1573568