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缩特性研究
Alternative TitleCompression Behaviors of Bentonite-Sand Mixtures as Buffer/Backfilling Materials
贾灵艳
Thesis Advisor张虎元
2013-05-25
Degree Grantor兰州大学
Place of Conferral兰州
Degree Name硕士
Keyword高放废物 缓冲回填材料 膨润土-砂混合物 压缩系数 有效粘土密度 有效含水率
Abstract高放废物以其放射性水平高、毒性大、发热量大和核素半衰期长等特点严重威胁人类生存和社会发展,将其长期可靠地与人类生存环境相隔离是保证人类社会可持续发展的必要工作之一,已引起国际社会的广泛关注。目前国际上比较公认的处置方法是深地质处置,它是基于“多重屏障体系”的概念模型,将高放废物封存在地表以下500-1000m的稳定岩体中,利用废物固化体、包装容器、缓冲回填材料和天然地质体4大屏障来阻止核素迁移,其中缓冲回填材料在减缓地下水渗流、阻止核素迁移、维持废物容器稳定及传递核素衰变产生的热量等方面起着至关重要的作用,它是阻隔放射性核素向地下水环境迁移的最主要包封措施。 高庙子钠基膨润土以其优越的吸附性能、膨胀自愈性能、极低的渗透性能和一定的力学强度作为本国缓冲回填材料的首选。然而,将纯膨润土作为缓冲回填材料存在2个难以克服的弊端:热传导性能低和可施工性差。将其作为缓冲回填材料的主料,向膨润土中添加一定比例的石英砂形成高庙子膨润土-砂混合型缓冲回填材料,可以在不显著降低上述优越性能的前提下,明显改善热传导性和可施工性。目前,将膨润土-砂混合物作为缓冲回填材料已是国际高放废物地质处置领域的主流方向。 研究混合型缓冲回填材料性能的根本目的在于:确定最优掺砂率,使高庙子膨润土-砂混合物的防渗性能、热传导性能、膨胀自愈性能、力学性能等同时满足高放废物地质处置的需求,确保高放废物与生物圈的永久隔离。本研究的具体目标是从压缩性能出发,研究高庙子膨润土-砂混合物的压缩性质与干密度、掺砂率的变化关系,为最优掺砂率的确定提供相关依据。试验结果表明:随着干密度的增大,压缩系数a1-2呈二次曲线减小;随着掺砂率的增大,压缩系数a1-2呈非线性增大。通过引入有效粘土密度和有效含水率的概念,对不同干密度、掺砂率的膨润土-砂混合物的压缩系数a1-2进行解释,并根据试验数据得到了回归的数学模型,试图为我国缓冲回填材料的配比优化研究提供相关依据。
Other AbstractHigh-level radioactive waste(HLW) can make great harm to natural environment and development of human society because of its strong radioactive, toxicity, heat and long half-life nuclides. It is absolutely necessary to reliably isolate HLW with the living environment of human in the long-term. Attentions have been devoted in recent years to the challenge of how to safely sotre HLW, which is the most important subject in the field of nuclear waste disposal. The deep geological disposal is currently believed to be the best feasible disposition way, which is based on the conceptual model of a multiple barrier system. The model combines an isolating geological environment with an engineering barrier system including the vitrified HLW, canister, and buffer/backfilling materials to seal HLW up safely at a depth of 500-1000m below the surface, in which the buffer/backfilling materials are the most inportant barrier to prevent the migration of radionuclides by groundwater. The buffer/backfilling materials play an absolutly important role in slowing groundwater seepage, preventing nuclide migration, keeping the stability of disposal canister and transferring nuclide decay heat. As buffer/backfilling materials of the geological HLW repository in China, GMZ bentonite is the preferred choice because of its high absorption and good swelling sealing and low permeability and considerable mechanical strength. However, the pure GMZ bentonite as buffer/backfilling materials has two limitation which are low thermal conductivity properities and poor constructability. As a modern trend in the develpoment of buffer/backfilling materials, bentonite is optimized by addition of certain content of quart sand to improve the thermal conductivity properities and constructability without obvious lowering of permeability and swelling properties. The prime aim to the compacted bentonite-sand mixtures is to investigate the optimum sand addition, under which the mixtures will provide a best adsorption to radionuclides, impermeability, thermal conductivity, swelling sealing and mechanical strength for meeting the requirments of HLW disposal at the same time. As a specific research, objectives of this study is to reveal the compression properties of bentonite-sand mixtures with different dry densities and sand ratios performed by WG oedometer, providing a basal data for the final optimum ratio of sand content of bentonite-sand mixtures. It is found that the compression coefficient a1-2 d...
URL查看原文
Language中文
Document Type学位论文
Identifierhttps://ir.lzu.edu.cn/handle/262010/226304
Collection土木工程与力学学院
Recommended Citation
GB/T 7714
贾灵艳. 混合型缓冲回填材料压缩特性研究[D]. 兰州. 兰州大学,2013.
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