Analysis of Membrane Penetration in Triaxial Test

The results of triaxial tests on coarse‐grained soils are often strongly influenced by the effects of membrane penetration. Analytical attempts at description of and experimental attempts at elimination of membrane penetration have not been successful. An analytical expression for the variation of membrane penetration volume change with net membrane pressure is developed. The expression is obtained from an approximation to the deformed shape of a membrane stretched across a regular array of uniform spheres. Laboratory tests performed on regular arrays of spheres and on coarse‐grained soils verify the ability of the expression to represent membrane penetration behavior accurately.