Research on Pipeline Flotation

Equations are proposed for determining the flotation force on the pipe using soil and pipe unit weights and pipe diameter. Equations are also used to estimate the resisting force to pipe flotation from the soil shear strength and pipe diameter. There is no effect of pipe depth on flotation within a range of one-half to two times the pipe diameter. The rate of pipe flotation is affected by the unit weight of pipe and contents. Tests were performed using four cohesive soils with different plasticity indices and short pipe sections of varying diameters. Sealed pipe sections were placed in a tank filled with soil at different water content. The soil unit weight, water content, and cohesive strength were determined. The unit weight of a pipe could be changed by the addition or removal of water. The unit weight of the pipe at the start of flotation was determined for each soil water content. Several pull-out tests were performed.