Premium
Numerical modelling on water retention and permeability of compacted GMZ bentonite under free‐swelling conditions
Author(s) -
Ni Hongyang,
Liu Jiangfeng,
Guo Jingna,
Yang Diansen,
Chen Yonggui
Publication year - 2020
Publication title -
international journal for numerical and analytical methods in geomechanics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.419
H-Index - 91
eISSN - 1096-9853
pISSN - 0363-9061
DOI - 10.1002/nag.3078
Subject(s) - environmental scanning electron microscope , water retention , bentonite , shrinkage , porosity , materials science , permeability (electromagnetism) , relative humidity , geotechnical engineering , swelling , scanning electron microscope , water content , composite material , soil science , soil water , chemistry , environmental science , geology , thermodynamics , physics , biochemistry , membrane
Summary In this study, a solid–liquid–gas coupled equation was established to simulate water retention characteristics of highly compacted GMZ bentonite. Then, modelling results were compared with laboratory test results. Results indicate that GMZ bentonite has a strong moisture expansion (or a limit drying shrinkage) characteristic. The control equation can simulate the water absorption and deformation characteristics very well at high relative humidity (or low suction). Environmental scanning electron microscope (ESEM) observation reveals the course grain soil texture of the surface under low relative humidity (RH), while the surface of GMZ bentonite becomes smooth (more fine‐grained soil texture) as RH increases. Differences were found between the porosities calculated by macroexperiment results and microscopic observations with ESEM method. This is because only the interaggregate pores can be observed by ESEM photographs. Additionally, we find that the simulated effective porosities are close to the results calculated by microscopic tests, while the effective porosity is considered as the main flow channel of flow. Further, the intrinsic permeability, the effective water and gas permeability are calculated based on the proposed model. The modelling results coincide well with the laboratory experimental results and support the reliability of the proposed model.