Membrane Compliance and Liquefaction of Sluiced Gravel Specimens

Membrane compliance significantly increases the liquefaction resistance of gravelly soils determined by undrained, cyclic triaxial tests. The mechanisms of membrane compliance are discussed in this paper. The liquefaction resistance of 2.8‐in. (71‐mm) and 12‐in. (305‐mm) diameter triaxial gravel specimens are presented in this paper for two conditions: (1) A typical membrane compliance system; and (2) a very low compliance system. The low‐compliance system is created by sluicing the gravel specimens with sand so that the peripheral specimen voids are filled, significantly reducing penetration during consolidation. The liquefaction resistance of sluiced specimens is found to be about 60%‐65% of unsluiced specimen values. Residual pore pressure ratios of 100% develop in sluiced specimens for values of cyclic stress ratio and number of stress cycles causing about 12% residual pore pressure ratio in unsluiced specimens. It is concluded that tests performed on sluiced gravel specimens significantly reduce membrane compliance and provide a more accurate assessment of the noncompliant liquefaction resistance of gravel specimens.