非饱和花岗岩气体相对渗透率试验研究

Experimental Study on Gas Relative Permeability of Unsaturated Granite

围岩气体渗透特性是影响高放废物处置库长期安全性的重要因素。以中国高放废物地质处置首选预选区——甘肃北山预选区的黑云母二长花岗岩为研究对象,开展了不同饱和度条件下的气体渗透率试验研究。首先利用真空饱和法获得了饱和试样,之后在6种不同相对湿度环境下完成了饱和花岗岩失水过程的监测,并测试了不同饱和度条件下的气体渗透率。随后分别在高放废物地质处置工程围岩预设最高温度90℃及沸点以上105℃条件下完成试样干燥过程,同时测试了干燥条件下的气体渗透率。基于测试结果,计算获得了花岗岩水分特征曲线,并分析了饱和度与气体相对渗透率的对应关系,并提出了数学描述模型。

Gas permeability of surrounding rock plays an important role in the long-term safety of the high-level radioactive waste（ HLW） disposal repository. The gas permeability of the biotitic monzogranite from Beishan area,where is the most potential area for China HLW disposal,was studied under different saturation conditions. The samples were firstly water-saturated by vacuum method. The desorption process of the saturated granite under six different relative humidities was then monitored and the gas permeability of each sample was tested at the end of desorption. The samples were then dried at 90 ℃,which is the preset maximum temperature of the surrounding rock for HLW disposal,and 105 ℃. Based on the test results,the sorption isotherm and the gas relative permeability were calculated and analyzed. The relationship between saturation and gas relative permeability was then discussed and a mathematical model was proposed.