Abstract
Hydraulic model experiment and on-site measurement of an actual construction site were carried out focusing on the type and method of operation of the bucket in the grab dredging. The characteristics of the flow field at the time bucket lowering-hoisting is revealed. And it was further investigated bucket operation method for inhibiting diffusion and turbidity occurs. As a result, rather than operating the bucket at a uniform lowering speed, by decelerating the lowering speed on the way, it was confirmed that can inhibit the flow velocity generated in the bottom surface. For normal bucket as compared to a sealed bucket was revealed that flow generated during lowering is small. Further, even when the hoisting operation, when the hoisting speed of the bucket is slow, it was confirmed that it can inhibit the flow generated around. Such an effect of the reduction of the lowering-the hoisting speed of the bucket was also confirmed in the field measurement.
