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Abstract 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.
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2015, Vol. 34 
