American Society of Civil Engineers

Triaxial Apparatus for Applying Liquid Infiltration with Controlled Boundary Conditions and Internal Suction Measurement

by Greg Siemens, A.M.ASCE, (Asst. Prof., GeoEngineering Centre at Queen’s-RMC, Kingston ON, Canada. E-mail: and James Blatz, P.Eng., M.ASCE, (Assoc. Prof., Univ. of Manitoba, Winnipeg MB, Canada R3T 5V6. E-mail:

Journal of Geotechnical and Geoenvironmental Engineering, Vol. 133, No. 6, June 2007, pp. 748-752, (doi:

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Document type: Technical Note
Abstract: This note describes a triaxial apparatus that applies liquid infiltration under automatically controlled boundary conditions while using the new Xeritron sensor to measure suction. Three different infiltration boundary conditions of interest including constant mean stress (CMS), constant volume (CV), and constant stiffness (CS) are applied to examine the influence of boundary conditions on the mechanical and hydraulic behavior of unsaturated clay materials. CMS and CV tests provide limits of infiltration boundary conditions while CS tests represent a flexible spring-type boundary condition. Spatial distribution of gravimetric water content and bulk density are measured to calculate dry density and degree of saturation following testing to determine internal changes to the specimens. The results from initial testing show that the apparatus is providing experimental evidence to evaluate unsaturated flow models and elastic-plastic constitutive models to examine the behavior of swelling clay soils under varying confinement conditions.

ASCE Subject Headings:
Laboratory tests
Swelling (material)
Triaxial tests
Unsaturated flow