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Skin friction values reported in the literature for stoppages of various durations.

Skin friction values reported in the literature for stoppages of various durations.

Source publication
Conference Paper
Full-text available
In long pipe-jacking drives used for installing utility pipelines, maximum jacking load requirements are usually governed by skin friction at the pipe-soil interface. In addition, field experience has shown that transient peaks in skin friction arise upon recommencement of jacking after stoppages; these stoppage durations can be short (due to the a...

Contexts in source publication

Context 1
... field experience has shown that transient peaks in the skin friction (i.e. the shear force divided by the embedded pipe surface area) arise upon restarting jacking after a stoppage; these stoppages can be short (due to the addition of a pipe to the string, for example) or long (due to weekend work breaks or breakdowns). The selection of field data from the literature in Table 1 illustrates that longer stoppages give rise to greater skin friction increases upon restart in any one drive, representing increased risk for the pipe-jacking contractor. However, there is no consistency in the magnitudes of these increases across the variety of ground conditions represented in Table 1, although it is acknowledged that the type and extent of lubrication will also have an impact on these values. ...
Context 2
... selection of field data from the literature in Table 1 illustrates that longer stoppages give rise to greater skin friction increases upon restart in any one drive, representing increased risk for the pipe-jacking contractor. However, there is no consistency in the magnitudes of these increases across the variety of ground conditions represented in Table 1, although it is acknowledged that the type and extent of lubrication will also have an impact on these values. This hampers accurate prediction of jacking force requirements. ...
Context 3
... shorter duration stoppage data are reproduced in Fig. 7, with the time axis plotted on a log scale due to the apparent skin friction intercept in Fig. 6. Also included are the skin friction increases quoted in Table 1 relevant to sandy soils (i.e. Pellet-Beaucour and Kastner 2002, Cheng et al. 2017) superimposed. ...