Rate Effect on Lateral Soil Restraint of Pipelines

Abstract

The purpose of this study was to determine the pipeline lateral soil restraint due to relative movement between the pipeline and the dry sand. A large scale drag device with dimensions of 6' × 6' × 4' (1.8 m × 1.8 m × 1.2 m) had been fabricated to study the primary variables such as sand density, pipe diameter, pipe burial depth and relative velocity on the pipe lateral soil restraint. All 120 test results indicated that the dimensionless maximum soil restraints and the corresponding displacements exhibited the power law relationship with the pipe velocity, V/D. In dense sand, the pipe velocity exponents, n, were found constant and be irrespective of pipe burial depth, however, values of n increased with burial depth in loose sand and emerged with the dense sand constant exponent at the burial depth of 10.5 times of pipe diameter. Also, the generalized maximum soil restraints increased with depth of burial, until the burial depths with H/D of 10.5 in loose sand and of 12.5 in dense sand were reached, at which points, the soil restraints became constant. Force-displacement relationship of pipe-soil interaction could be represented by a two- constant hyperbolic equation. These two constant values of a and b were found to have the power law relationship with the pipe velocity, V/D.