ANALYTICAL INVESTIGATION ON DISTURBANCE OF SOIL SPECIMEN SAMPLED FROM SEABED GROUND AND ITS INFLUENCE ON LABORATORY TEST

In view of the need to utilize ocean space and develop seabed resources, the assessment of the stability of deep seabed soil has emerged as an important challenge in the field of geomechanics. To study seabed stability, the consolidation characteristics and strength of the natural ground must be ascertained. However, soils sampled from the ocean bottom are subject to effects that differ from those exerted from sampling on earth. More specifically, non-negligible effects of disturbance are expected. Therefore, we conducted numerical simulations to investigate the effects of vaporizing dissolved gases on the mechanical behaviors of soil specimens during sampling and on the consolidation characteristics and undrained shear strength as determined by laboratory tests. The analyses revealed that the interaction between decreasing effective stress caused by sampling, overconsolidation and desaturation causes the difference between the soil strength ascertained by laboratory testing and in-situ soil strength.