Winkler load-transfer analysis for pipelines subjected to surface load

Abstract

Construction loads cause extra deformation and stress to nearby buried municipal pipelines. This paper investigates this issue by relating problems with inputs as free-field soil pressure or displacement by surface loading to the choice of an appropriate Winkler subgrade modulus for pipeline-soil interaction mechanisms. The theoretical analysis indicates that the input of surface load-induced soil pressures at the pipeline location results in much smaller moments and displacements of the pipeline. Although the Winkler solution using the Vesic spring modulus results in the same bending for a beam resting on the soil surface as that in elastic continuum when under a point load, its use is not always adequate for a buried pipeline with a finite embedment depth under external load and when subjected to free soil movements. An alternative expression for the spring modulus is given for a buried pipeline under a direct external load. The application of a passive Winkler modulus is proven rational when the pipeline is subjected to soil movement. A comparison between FEM analysis and the elastic continuum solution suggests that a displacement input or a coupled input be used for the analysis of a pipeline under surface loading, together with the application of a modified active Winkler modulus expression considering embedment depth and a passive Winkler modulus expression for surface loading–pipeline–soil systems under different input conditions.