Experimental study on the migration regularity of sand outside a large, deep-water, open caisson during sinking

摘要

Based on the sinking construction of the largest open caisson across the world, a sinking simulation test is designed and conducted in this work. Data from sensors during subsidence, the migration track of the sand outside the caisson and the settlement of the riverbed after the sinking are measured and analysed. The relationships between the influence range of sand migration outside the caisson and the sinking depth, and the characteristics of the subsidence space formed after migration are described. Combined with measured data from caisson construction, the migration of sand outside the caisson is concluded to be mainly related to the depth of the caisson and the spatial position of the sand outside the caisson and to be influenced by the seepage force, the blade foot reaction force and the lateral pressure. A calculation model describing the behaviour of the migration is established through dynamic comparison and analysis. It is found that the seepage force, the blade foot reaction force, the lateral pressure, sand gushing and sudden sinking of the caisson are all related to the sand migration. A migration coefficient is defined to describe the migration rate and different degrees of sand gushing and sudden sinking.