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+--- Thread: Omission in interpolation calculation Z_GROUND in PROFILE table (/thread-436.html)
Omission in interpolation calculation Z_GROUND in PROFILE table - shaswin - 17-08-2014
Affected PLE version: 4.2.3
Hello, there is a omission in the calculated values of Z_GROUND in the PROFILE output table. An example is given below:
[attachment=548]
The educational PLE project file (zipped) has also been attached for the analysis.
At the 'start' (node 6) and 'end' (node 22) of the bend I get a Z_GROUND of 1707.1 mm in AutoCAD. PLE gives in the PROFILE output table a Z_GROUND of 1655 mm at the bend ends, see picture below:
[attachment=549]
This calculation error is always reproducible when bends are used in the POLYDIF.
Column W_LEVEL in the PROFILE table is also affected with the same error.
I have also tried different configurations in AutoCAD to verify the Z_GROUND. The error of the Z_GROUND at bend nodes are structural in PLE.
It is important that the Z_GROUND is correct, because PLE uses the PROFILE output table in the Soil Model Wizard to calculate the soilparameters.
RE: Omission in interpolation calculation Z_GROUND in PROFILE table - shaswin - 22-08-2014
Another example:
IDENT D20B1s: node 10, Z_GROUND PLE: 1641 mm, AutoCAD: 1621.6 mm
IDENT D20B1e: node 20, Z_GROUND PLE: 1496 mm, AutoCAD: 1475.2 mm
IDENT D20B2s: node 24, Z_GROUND PLE: 1176 mm, AutoCAD: 1169.9 mm
IDENT D20B2e: node 28, Z_GROUND PLE: 1148 mm, AutoCAD: 1148.5 mm
IDENT D20B3s: node 37, Z_GROUND PLE: 1767 mm, AutoCAD: 1762.5 mm
IDENT D20B3e: node 43, Z_GROUND PLE: 2000 mm, AutoCAD: 2000.0 mm
There is also difference in this example.
Column W_LEVEL in the PROFILE table is also affected with the same error.
RE: Omission in interpolation calculation Z_GROUND in PROFILE table - Ing. Henk Olie - 19-11-2014
Omission in interpolation calculation Z-GROUND.
Although this remark is understandable, Ple4Win calculates the Z-GROUND values as intended.
IDENTS are linked to NODES. Defining G-LEVEL using IDENTS means input is provided for nodes 1, 12 and 23. The other nodes (2-11 and 13-22) will get interpolated values.
As nodes are always located on the pipeline axis, interpolation is done using the AX-L value of the nodes.
The resulting Z-GROUND of node 4 is 1654.710 leading to a soil cover of some 948 mm
Using X coordinates (0, 1000 and 2000 mm) as input for G-LEVEL the Ple4Win generated
Z-GROUND values will form straight lines, and results in a Z-GROUND of 1707.107 mm.
Of course we can discuss a different approach in the future.
Please refer to the screen shot.
RE: Omission in interpolation calculation Z_GROUND in PROFILE table - shaswin - 30-11-2014
Your point is clear. There is no need for a new approach, because the differences are small in the most cases.