The Stable State in Cyclic Triaxial Testing on Sand

Abstract The paper will describe a number of new characteristic phenomena of sand under cyclic loading, which have been discovered by triaxial cell testing, at the Soil Mechanics Laboratory at Aalborg University using test specimens with equal height and diameter. These phenomena have been compared with results from tests executed on specimens with double height. It will be explained why the new phenomena ‘Stabilization’ and ‘Instant Stabilization’ are seldom observed when the test is executed on specimens with double height. The conclusion recommends that the study of pore pressure variation due to cyclic loading should only be performed with smooth pressure heads and specimens with equal height and diameter because the phenomena leading to stress hardening would otherwise not be observed.