兰州大学机构库 >土木工程与力学学院
混合型缓冲回填材料压实性能研究
Alternative TitleCompaction properties of GMZ bentonite-sand mixture as buffer material for HLW disposal
梁健
Thesis Advisor张虎元
2009-05-28
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword高放废物 深地质处置 缓冲回填材料 膨润土-砂 动力击实 静力压实
Abstract高放废物含有放射性强、发热量大、毒性大、半衰期长的核素,需要与人类生存环境长期、可靠地隔离。深地质处置是目前可行性最好的处置方案。高放废物深地质处置的工程屏障体系中,缓冲回填材料是阻截放射性核素向地下水环境迁移的最主要包封设施。膨润土因具有极低的渗透性和极高的吸附性,是理想的缓冲回填材料。但使用纯膨润土作为缓冲回填材料,存在两个难以克服的弊端。一是膨润土的热传导性能低,不利于放射性废物辐射热量散发到周围的洞室围岩中去,可能导致缓冲层温度升高超过100˚C,液态水气化后产生过大的水汽压力;二是纯膨润土塑性过高,加水制样过程中“团粒化”倾向及不均匀湿化现象极其明显,可调理性差,难以压实到预定的最大干密度。 目前,开发膨润土-砂混合物作为缓冲回填材料,是世界高放废物地质处置领域的主流方向。膨润土中添加一定量的石英砂,既能满足力学强度、热传导性能和防渗阻隔能力,又能优化回填设计与施工性能。1985年以来,我国高放废物处置领域关于缓冲回填材料的研究,主要围绕膨润土主料的筛选,初步认为,内蒙古高庙子膨润土是我国高放废物缓冲回填材料的适宜材料。高放废物地质处置设施中缓冲回填材料施工,目前的预想方案有两类:现场原位压实法、预制块现场砌筑法。因此,本文试验研究了内蒙古高庙子钠基膨润土添加不同含量石英砂之后的动力击实和静力压实性能,分析了较低、较高掺砂率和压实能影响压实效果的可能机理,以及最大干密度与最优含水率相关关系。 研究数据表明,不同掺砂率的膨润土-砂混合物,最大干密度与最优含水率存在统一的幂函数关系,而与压实方法及压实能大小无关。对于不同的压实方法及压实能大小,最优含水率与掺砂率之间存在线性关系。利用这些关系,就可以针对特定的压实目标选择适宜的压实方法。研究认为,高庙子膨润土掺加10%~30%的石英砂有助于改善压实质量,同时防渗性能也不会降低。
Other AbstractHigh-level radioactive waste which contains strong radioactive, heat, toxicity, and long half-life nuclides must be long-term and reliably isolated with the living environment of the human. The deep geological disposal is currently believed to be the best feasible disposition. Due to its very low permeability and excellent retardation of nuclides from migration, the bentonite is selected as base material of the backfill/buffer material in HLW repositories. However the pure bentonite as the backfill/buffer material has two limitations. One is that low thermal conductivity properties is not helpful to conducting the heat of radiation into the surrounding rock in the cavern, that causes the buffer layer temperature raise to more than 100˚C and water vapor pressure. Anther is that it has bad workability, which is difficult to compact to the maximum dry density. As a modern trend in backfill/buffer material development, bentonite is optimized by addition of certain content of quart sand to improve the strength and heat conductivity without obvious lowering of permeability. Since 1985, GMZ bentonite was preliminary confirmed as the backfill/buffer materials for high-level radioactive waste disposal. The expected methods for the construction of backfill/buffer materials included In-situ compaction and prefabricated masonry block law. For this reason, Dynamic compaction and Static compaction tests were carried out in laboratory on the mixture of GMZ bentonite and artificial quart sand to illustrate the effects of sand mixing ratio and compaction pressure and to show the relationship of the max dry densities and the optimum water content. Test results show that the relationship between maximum dry density and optimum water content follow the same power function for all of the mixture specimens prepared, while there is a linear correlations between mixture specimens prepared in different compaction methods and compaction efforts. These correlation functions provide useful tools for convenient selection of compaction methods in practice. It is concluded that addition of 10-30% quartz sand to GMZ bentonite can improve the compaction quality with no altering the impermeability of the backfill/buffer material.
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226305
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
梁健. 混合型缓冲回填材料压实性能研究[D]. 兰州. 兰州大学,2009.
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