高效废物处置库的混合型缓冲回填材料压缩特性研究

高放废物处置库中缓冲回填材料需要预先压缩到一定密实度，其压缩特性对处置库的安全设计、施工及运营有重要影响。目前，国内初步考虑将膨润土-砂混合物作为缓冲回填材料的首选。采用WG型单杠杆固结仪，对不同干密度、掺砂率的膨润土-砂混合物进行侧限压缩试验研究。试验结果表明：随着干密度的增大，压缩系数呈二次曲线减小；随着掺砂率的增大，压缩系数呈非线性增大。通过引入有效黏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进行解释，并根据试验数据得到了回归的数学模型，试图为缓冲回填材料的配比优化研究提供相关依据。

Compression behaviors of compacted bentonite-sand mixtures as buffer material for HLW disposal

In high-level radioactive waste(HLW) repository, buffer backfilling material should be pre-compacted to a certain density. The compression properties of buffer backfilling material have an important influence on the safety design, construction and operation for geological HLW repository. At present, bentonite-sand mixtures are considered to be the ideal buffer backfilling material in the geological HLW repository in China. the compression properties of bentonite-sand mixtures with different dry densities and sand ratios, whose water content is constant, are performed by WG oedometer. It is found that the compression coefficient a1-2 decreases quadratically with the increase of dry density, but it increases nonlinearly with the increase of sand ratio. Based on the concepts of effective clay density and effective water content, we try to explain the changes of the compression coefficient a1-2 with dry density and sand ratio. The regression analysis model of bentonite-sand mixtures with various dry densities and sand ratios are fitted based on the experimental data, and it hopes that this result can be used to provide a related basis of the optimization of buffer backfilling material.