膨润土–砂混合型缓冲/回填材料渗气规律试验研究

EXPERIMENTAL STUDY OF GAS PERMEABILITY OF BENTONITE- SAND MIXTURES AS BUFFER/BACKFILLING MATERIALS

为研究高庙子膨润土–砂混合型缓冲/回填材料的渗气规律,利用改进的三轴渗气试验装置,对不同掺砂率、干密度和含水率的混合物试样进行一系列试验研究。结果表明:在试验研究的条件范围内,膨润土–砂混合物(含纯膨润土)的渗气系数为3.9×10-4~2.1×10-2 cm/s;膨润土–砂混合物的渗气规律遵循Darcy定律,但较高的气压力梯度对渗气系数值存在一定的影响;掺砂率、干密度和含水率均对混合物的渗气性质有影响,混合物的渗气系数随掺砂率增加呈指数形式增加,随干密度和含水率增加呈指数形式降低;在试验研究范围内建立了考虑不同条件下的混合物渗气系数的公式,与试验结果吻合较好。得到的一系列试验数据能为我国高放废物地质处置库的建设提供科学依据。

The improved triaxial gas permeable apparatus device was employed to conduct a series of experiments for sample of mixture with different sand ratios,dry densities and water contents in order to study the law of gas permeability of GMZ bentonite-sand mixture buffer/backfill materials. The result shows that within the range of experimental condition,the gas permeability coefficient of bentonite-sand mixture(including pure bentonite) is between 3.9×10-4–2.1×10-2 cm/s. Gas flow of bentonite-sand mixture materials can be expressed by Darcy law,but higher gas pressure gradient has certain influence to figure of gas permeability coefficient,and sand ratio,dry density and water content have effect on gas permeability of mixture respectively. The gas permeability ratio of mixture increases exponentially with the increase of sand ratio,while decreases exponentially with the increase of dry density and water content. The gas permeability coefficient formulas of mixture under different conditions were set up within the range of experimental research,which coincide well with the experimental result. A set of experimental data can provide scientific basis for the construction of HLW(high-level radioactive waste) geological disposal in China.