Effect of void formation on strength of cemented sand

摘要

Gas hydrate dissociation can generate large amounts of gas and water in gas hydrate bearing sediments, which may eventually escape from a soil skeleton and form local voids within the sediments. Such void formation may impact the strength of gas-hydrate-bcaring submarine slope. In this study, the effect of local void formation arising from gas hydrate dissociation, loss of fine particles or dissolution of vanishing materials is examined in terms of unconfmed compressive strength. Glass bead, cement and water arc mixed and compacted into a cylindrical specimen with five equal layers to simulate base soil structure. Empty capsules for medicine arc used and embedded into the middle of five equal layers to mimic relatively large voids which are disconnected and permanent. The number and direction of capsules in each layer varies. A scries of uncontined compression tests was performed on capsule-embedded cemented glass beads. Unconfmed compressive strength of cemented glass beads with capsules decreased up to 35% of one without capsule due to increasing void formation, which depends on the amount and direction of embedded capsules. The results of this study can be used to predict the strength reduction of soils due to locally disconnected large voids.