Effects of temperature and thermally-induced microstructure change on hydraulic conductivity of Boom Clay

作     者：W.Z. Chen Y.S. Ma H.D. Yu F.F. Li X.L. Li X. Sillen 

作者机构：Research Centre of Geotechnical and Structural Engineering Shandong University Jinan Shandong 250061 China State Key Laboratory of Geomechanics and Geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of Sciences Beijing 100049 China European Underground Research Infrastructure for Disposal of Nuclear Waste in Clay Environment EIG Euridice Mol 2400 Belgium ONDRAF/NIRAS Brussel 1210 Belgium 

出 版 物：《Journal of Rock Mechanics and Geotechnical Engineering》 (岩石力学与岩土工程学报（英文版）)

年 卷 期：2017年第9卷第3期

页      面：1-13页

核心收录：

学科分类：08[工学] 0818[工学-地质资源与地质工程] 080104[工学-工程力学] 0815[工学-水利工程] 0813[工学-建筑学] 0814[工学-土木工程] 0801[工学-力学（可授工学、理学学位）] 

基　　金：financial support of the National Science Foundation for Distinguished Young Scholars (Grant No. 51225902) Natural Science Foundation of China (Grant No. 51479190) EURIDICE (European Underground Research Infrastructure for Disposal of Nuclear Waste in Clay Environment, Mol, Belgium) for the work presented in this paper 

主　　题：Boom Clay Permeability Thermal effect Anisotropy Microstructure 

摘      要：Boom Clay is one of the potential host rocks for deep geological disposal of high-level radioactive nuclear waste in Belgium. In order to investigate the mechanism of hydraulic conductivity variation under complex thermo-mechanical coupling conditions and to better understand the thermo-hydromechanical(THM) coupling behaviour of Boom Clay, a series of permeability tests using temperaturecontrolled triaxial cell has been carried out on the Boom Clay samples taken from Belgian underground research laboratory(URL) HADES. Due to its sedimentary nature, Boom Clay presents acrossanisotropy with respect to its sub-horizontal bedding plane. Direct measurements of the vertical(Kv)and horizontal(Kh)hydraulic conductivities show that the hydraulic conductivity at 80℃ is about 2.4 times larger than that at room temperature(23℃), and the hydraulic conductivity variation with temperature is basically reversible during heatingecooling cycle. The anisotropic property of Boom Clay is studied by scanning electron microscope(SEM) tests, which highlight the transversely isotropic characteristics of intact Boom Clay. It is shown that the sub-horizontal bedding feature accounts for the horizontal permeability higher than the vertical one. The measured increment in hydraulic conductivity with temperature is lower than the calculated one when merely considering the changes in water kinematic viscosity and density with temperature. The nuclear magnetic resonance(NMR) tests have also been carried out to investigate the impact of microstructure variation on the THM properties of clay. The results show that heating under unconstrained boundary condition will produce larger size of pores and weaken the microstructure. The discrepancy between the hydraulic conductivity experimentally measured and predicted(considering water viscosity and density changes with temperature) can be attributed to the microstructural weakening effect on the thermal volume change behaviour of Boom Clay. Based on the ex