Investigation on Compression and Permeability Behaviour of Bentonite with the Coupling of Load-Solution

The consolidation tests of Na-bentonite saturated with NaCl, KCl and CaCl₂ are conducted to study the influences of salt-load coupling effect on consolidation property and saturation permeability of bentonite. The results show that: The volume deformation of compacted bentonite decreases with the increase of consolidation stress, and the load grade jumps have a significant effect on the variable properties of bentonite soaked with high concentration NaCl solution. With the increase of vertical consolidation stress under the action of NaCl and CaCl₂, the compacted bentonite samples changed from elastic state to plastic state, and the compression coefficient first increased and then decreased, while the compression coefficient always decreased under the action of KCl solution. The saturation permeability coefficient of bentonite indirectly calculated by Terzaghi one-dimensional consolidation theory ranges from 4.006 × 10^-13 m/s ~ 1.975 × 10^-11 m/s. With the increase of solution concentration, the content of interlayer bound water of montmorillonite decreases, the free water flow path widens, and the permeability coefficient increases correspondingly. By introducing the modified effective force in salt solution, it is found that the equation y = x^-1 × (Alnx+B) can be used to describe the saturated permeability coefficient of bentonite and the effective stress.