某高放废物处置库裂隙岩体显微结构及渗透性研究

Microstructure and permeability study of the fractured rock mass at a high-level radioactive waste disposal repository

高放废物处置库通常选址在具有低渗、闭合等特点的岩体内,因此研究低渗透性裂隙岩体的内在结构及渗透特性至关重要。以甘肃北山处置库围岩结构面为对象,采用原位压水试验确定裂隙岩体渗透系数,结合岩芯CT扫描建模研究裂隙岩体内在显微结构。结果表明:压水试验确定的裂隙渗透系数为10^-6~10^-8m/s,水力张开度为0.027~0.044mm,与钻孔水文地质资料揭露的渗透系数10^-6~10^-10m/s相互验证;结合岩芯CT扫描结果可知,裂隙岩体内在显微结构与其渗透性具有相关性。研究裂隙岩体内在结构及渗透特性参数,可以为地质处置库选址提供参考。

High-level radioactive waste disposal repository is usually located in rock mass with the characteristics of low permeability and closure of its geological structure surface,so it is very important to study the internal structure and permeability characteristics of low permeability fractures.Taking the surrounding rock structural surface of the disposal reservoir in Beishan of Gansu Province as the background,the permeability coefficient of the single-fractured rock mass is determined by using in-situ packer permeability tests,and the internal microstructure of the single-fractured rock mass is studied by combining the CT scanning modeling of the borehole core.The results show that the permeability coefficient of the single-fractured rock mass in small scale is determined by using the packer permeability tests to be10^-6~10^-8 m/s,and the hydraulic opening is 0.027~0.044 mm,which is mutually verified with the drilling hydrogeological data as permeability coefficient 10^-6~10^-10 m/s.Combined with the analysis of core CT scan results,it is concluded that the internal microstructure of fractured rock mass is correlated with its permeability.The study on the internal structure and permeability parameters of fractured rock mass could provide the reference for the site selection of geological disposal reservoir.