当前位置: X-MOL 学术Soils Found. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Sealing performance of compacted block joints backfilled with bentonite paste or a particle-powder mixture
Soils and Foundations ( IF 3.7 ) Pub Date : 2021-02-19 , DOI: 10.1016/j.sandf.2021.01.005
Ying Wang , Huyuan Zhang , Yu Tan , Jianghong Zhu

Technology gaps are inevitable parts of the buffer barriers in the high-level radioactive waste (HLW) repositories. The mechanical properties, permeability and water-solute-radionuclide migration of buffer barrier are different when considering the gaps. The present study was designed to investigate the sealing effect of joint between the compacted blocks with two types of sealing materials, a bentonite paste (P) and a bentonite particles and powder mixture (P/P) both from the macro- and micro-aspects.

A series of laboratory test was conducted to study the hydro-mechanical properties of bentonite blocks after backfilling the joint between blocks. Both the intake and outflow water volume, and the pressure on radial and axial direction were monitored during the hydration. Following the permeability test, the joint’s sealing was evaluated by a final dry density, water content distribution and microstructure evolution. The results showed that the axial and radial pressure of blocks backfilled with bentonite P and bentonite P/P mixture were higher than that of blocks with a blank joint. Pressure preferentially increased in the low-stress areas (the joint areas), contributing to sealing of the joint. The hydraulic conductivities for backfilled bentonite blocks were almost on the same order of magnitude as to intact bentonite blocks, revealing a clear sealed hydraulic behavior. The final dry density decreased in the block area and increased in the joint area after hydration, forming a transition zone with a certain width. A smaller difference was found between the block and joint area in the backfilled block. The mercury intrusion porosimetry (MIP) test and scanning electron microscope (SEM) test showed that backfill decreased the numbers of inter-aggregates pores ranged between 8 and 15 μm compared with that in the blank joint. The comprehensive data showed that a joint backfilled with a bentonite P/P mixture has a higher swelling capacity, lower permeability, and denser structure compared with joint backfilled with bentonite P. The results suggested that joint backfilling improved the integrity of the blocks and enhanced the swelling property and impermeability compared with that of the non-backfilled blocks. Both bentonite P and bentonite P/P has satisfactory sealing performance of compacted block joints, with better effect of the later.



中文翻译:

膨润土糊或颗粒粉混合物回填的压实块状接头的密封性能

技术差距是高放废物(HLW)处置库中缓冲屏障不可避免的部分。考虑间隙时,缓冲屏障的机械性能,渗透性和水溶质-放射性核素迁移是不同的。本研究旨在从宏观和微观两个方面研究压实块与两种类型的密封材料(膨润土糊(P)和膨润土颗粒与粉末混合物(P / P))之间的接合处的密封效果。 。

进行了一系列的实验室测试,以研究膨润土砌块之间的接缝回填后的力学性能。在水化过程中,监测进水量和出水量,以及径向和轴向的压力。经过渗透性测试后,通过最终的干密度,水含量分布和微观结构演变来评估接头的密封性。结果表明,回填膨润土P和膨润土P / P混合物的砌块的轴向和径向压力高于带有空白接头的砌块。优先在低应力区域(接头区域)增加压力,从而有助于密封接头。回填膨润土块的水力传导率与完整的膨润土块几乎相同的数量级,揭示了清晰的密封水力行为。水合后,最终的干密度在块区减小,在接缝区增加,形成具有一定宽度的过渡区。在回填块中,在块与接缝区域之间发现了较小的差异。压汞法(MIP)和扫描电子显微镜(SEM)测试表明,回填比空白接头减少了8至15μm的聚集体孔数量。综合数据显示,与膨润土P / P混合物回填相比,回填膨润土P / P混合物的接头具有更高的溶胀能力,较低的渗透性和更致密的结构。结果表明,与未回填砌块相比,联合回填改善了砌块的完整性,并提高了膨胀性和抗渗性。膨润土P和膨润土P / P均具有压实的块状接头的令人满意的密封性能,后期效果更好。

更新日期:2021-03-27
down
wechat
bug