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Possibly resulting total gap between pipeline element and soil
12-10-2017, 12:29 PM, (This post was last modified: 12-10-2017, 12:35 PM by shaswin.)
 shaswin Senior Member Posts: 379 Threads: 196 Joined: Dec 2008 Reputation: 0
Possibly resulting total gap between pipeline element and soil
Ref: Tables Reference > Output Tables > Additional cross-sectional loads [ADDCROS] > Data description/Result options / ID: H610541

Dear Support Staff,

According to the user manual, see below, a gap can be calculated according to U_Z - SETLZ*F - SOILNB / KLS > 0.

This is true in the case when the Z-coordinate of polygon point (n) is on the bottom of the pipeline.
In normal cases and cases when there is a large diameter a user will fill the Z-axis of the pipeline according to the screenshot below.

Does this mean that the gap can be calculated as U_Z - SETLZ*F - SOILNB / KLS - (DOUT / 2) > 0.
If correct than the note in helpfile should point out that the DOUT / 2 is conditional only for the case if Z-coordinate is the axis of the pipeline in POLYDIF.
26-10-2017, 04:55 PM,
 ir L Houtenbos Moderator Posts: 3 Threads: 0 Joined: Oct 2017 Reputation: 0
RE: Possibly resulting total gap between pipeline element and soil
Dear Shaswin,

The gap under an element is in table ADDCROS indeed calculated with the formula.
gap = U-Z - SETLZ*F - SOILNB / KLS

in which:
U-Z = displacement found for each node in table DISPLAC
SETLZ*F = applied settlement found for each node in table S-LOAD
SOILNB = top soil load found for each element in table CROSDAT
KLS = downward vertical soil stiffness found for each element in table LATSOIL

Please note that the U-Z and the SETLZ*F are both given for nodes, take the average values of the 2 element nodes to calculate the respective values for the element.

If we neglect the ovalisation the displacements of the pipe are equal at the pipe axis and the bottom of the pipeline. Also if we neglect settlement differences in the vertical soil profile, the settlement will be equal at the height of the pipe axis and at the bottom of the pipeline. Thus the location of the z-coordinate will not make a difference when calculating the gap height.

Futhermore, in Ple4Win the Z-coordinate is always the coordinate of the pipe-axis, never the coordinate of the pipe bottom.