Deepwater sample disturbance due to stress relief

Samples taken from seabed soils in deep water are subjected to a large stress relief. This paper presents the comprehensive study results of laboratory tests where deepwater sampling of clay with various amounts of gas dissolved in the pore water has been simulated. Measurements in triaxial and oedometer tests on Lierstranda clays show that the change in void ratio increases linearly with degree of gas saturation η,when reconsolidated to in situ stresses.Other measured parameters, like undrained shear strength, strain under peak shear stress, dilatancy parameter and preconsolidation stress, also vary systematically with η, showing that disturbance increases with η.The results obtained from the tests have been used to develop recommendations for optimal procedures to store and handle samples containing gas.