水-力-化耦合效应下膨润土衬垫防渗特性研究OA

A series of flexible-wall permeameter tests is conducted to investigate the effects of confining pressure and chemical solutions on the hydraulic performance of sodium bentonite-based geosynthetic clay liners(GCLs).The results show that under deionized water permeation,the hydraulic conductivity of GCLs decreases logarithmically with increasing confining pressure,indicating strong stress sensitivity.At low to moderate concentrations,divalent cations have a significantly greater detrimental effect on GCL performance than monovalent cations.While NaCl solutions cause less than an order-of-magnitude increase in hydraulic conductivity,CaCl2 solutions severely suppress the swelling capacity of bentonite,enlarge inter-granular voids,and result in up to five orders of magnitude increase in permeability with rising concentration.Additionally,physical disturbances such as wrinkling lead to non-uniform granular distribution and preferential flow paths,resulting in an approximately one-order-of-magnitude increase in hydraulic conductivity.Under coupled stress-chemical conditions,GCLs exhibit minimal sensitivity to confining pressure in low-concentration or monovalent cation solutions.However,in high-concentration divalent cation environments,increasing the confining pressure can reduce hydraulic conductivity by about three orders of magnitude;yet,the values still fail to meet the Chinese national standard of 10-11 m/s.At the mesoscale,granular size,spatial distribution,porosity,and the formation of continuous flow channels in bentonite are identified as key factors that governing the structural evolution and eventual hydraulic failure of GCLs.