Problem description

The data used to add a centerline From tunnel designer in PLAXIS Output are not correctly updated in the case of having an offset in the tunnel begin point position (General tab in the tunnel designer). This means that the centerline added in the Output program will not correspond to the updated position, resulting in wrong results for structural forces in volumes.

The problem can occur in two situations, when:

• generating a tunnel with an offset and a thick lining from the beginning [SOLVED SINCE 2D2015.02]
• editing the offset of an existing tunnel along with its thick lining (still occurs in 2D2015.02)

Figure .1 Output structural forces view: Centerline not updated when having tunnel with offset

Solution

In PLAXIS 2D 2016.00 you can now also use the automatic centerline tool to make sure to select the correct volumes for the structural forces determination.

One of the two problems has been solved in 2D2015.02: when you already have defined the offset before generating a thick lining, the centerline will be determined correctly. However, if after generating a thick lining you change the location of the tunnel (e.g. via Offset), the tunnel file is not updated anymore, resulting in the originally defined location.

We are working on a solution. For now we have this work around:

• To be able to update the centerline, manual editing of the data file is required. The related data file is located inside the project folder and by default it is named as data.otnl. The text format of the file is based on JSON (JavaScript Object Notation) and can be edited using any text editor, e.g. notepad from Windows. See the examples below:
  1. Creating a tunnel and thick lining with offset and
  2. Editing offset of an existing tunnel with thick lining
• For more information on the structure of the data.otnl file refer to the related article on Create centerline for Structural Forces in Volumes

1. Creating a tunnel and thick lining with offset

In the case of an arc type, the origin coordinates need to be updated. The offset displayed in the tunnel designer should be subtracted from the existing coordinates of the origin of the arc, in order to have the correct centerline data.

In the case of polyline, the coordinates of all points need to be updated. The offset displayed in the tunnel designer should be subtracted from the existing coordinates of the points of the polyline, in order to have the correct centerline data.

Example

Offset to begin point:
Axis 1 : 5.000
Axis 2 : 1.000

Existing data

Arc type:
"origin": [6.5, 1.3]
Polyline type:
"points" : [ [4.25, 1], [5.5, 3.5], [6.75, 1], [4.25, 1] ]

Corrected data

Arc type:
"origin": [1.5, 0.3]
Polyline type:
"points" : [ [-1.25, 0], [0.5, 2.5], [1.75, 0], [-1.25, 0] ]

2. Editing offset of an existing tunnel with thick lining

In the case of an arc type, the origin coordinates needs to be updated. The offset displayed in the tunnel designer should be added to the existing coordinates of the origin of the arc, in order to have the correct centerline data.
In the case of polyline, the coordinates of all points need to be updated. The offset displayed in the tunnel designer should be added to the existing coordinates of the points of the polyline, in order to have the correct centerline data.

Example

Offset to begin point is:
Axis 1 : 5.000
Axis 2 : 1.000

Existing data

Arc type:
"origin": [6.5, 1.3]
Polyline type:
"points" : [ [4.25, 1], [5.5, 3.5], [6.75, 1], [4.25, 1] ]

Corrected data

Arc type:
"origin": [11.5, 2.3]
Polyline type:
"points" : [ [9.25, 2], [10.5, 4.5], [11.75, 2], [9.25, 1] ]