Axis Translation and Negative Water Column Techniques for Suction Control

Negative water column and axis translation techniques are conventionally used experimental techniques for obtaining data to interpret the engineering behavior of unsaturated soils. The negative or the hanging water column technique is used as a suction control method in the low suction range (i.e., 0–30 kPa). The axis translation technique is used in the suction range 0 to 500 kPa or higher. This technique is particularly useful for testing specimens with suction values greater than 100 kPa avoiding problems associated with cavitation. While the axis-translation technique has been commonly used, the limitations associated with this technique related to air diffusion, water volume change and evaporation are not discussed in greater detail in the literature. This paper highlights some of the key aspects related to the negative water column and axis translation technique that are of interest both to the researchers and practicing engineers.