Pipe–soil interaction during pipe jacking

The purpose of this paper is to introduce some simple theoretical models of pipe--soil interaction during pipe jacking, and relate these to observations made in the field. Ground conditions, construction techniques and the degree of site control all influence the resistance to jacking of pipes, but if an appropriate model is chosen it should be possible to predict jacking forces with a reasonable degree of accuracy. Deviations of the pipeline from a straight line increase the jacking resistance. A new analysis, based on observations from the field monitoring, provides an explanation for the measured increases in pipeline resistance for pipes jacked through a stable bore; it highlights the important factors and emphasizes the need for careful control of pipeline alignment. Explanations are also sought for the apparently frictional behaviour in terms of total stress at the pipe–soil interface in firm and stiff cohesive soils. Time effects are shown to be important in high plasticity clays.