Advanced suction control techniques for testing unsaturated soils

Three suction control techniques(i.e.axis-translation,osmotic and humidity control) developed overseas were introduced and reviewed.The working principle,development,applications,advantages and limitations of each technique were described and discussed.Experimental data using the axis-translation and osmotic techniques were compared and discussed.Moreover,by applying different durations of suction equalization before shearing in a direct shear box,the influence of duration of suction equalization on subsequent shearing behaviour was illustrated in terms of shear strength and volume change.