Manual Trench Description¶
Introduction¶
In earlier versions of the software (version 13 and earlier), we used the surface description table in manual road to define trenches.
We can still do this in the same way. In addition, we can convert a parametric description to a manual description. It may be relevant to use manual road if we don't have a license for parametric trench (Gemini TrenchWorks) or need to make manual adjustments that the automation doesn't support.
Manual road requires that we have horizontal and vertical geometry defined in the SFI model.
We can then use the same tables as in road design to define the trench. It's common to start with a template. We have created two templates for a typical trench cross-section:
- Grøft-OV200mm.sfi (Trench-OV200mm.sfi)
- Grøft-OV200mmNy.sfi (Trench-OV200mmNew.sfi)
The trench cross-section is as shown in the figure:
A* = Road/terrain base, B* = Rock
In the trench cross-section, the 0-point for the reference height is the bottom exterior of the pipe, which means the top of the foundation.
How the templates are defined is described in detail below, as well as the advantages and disadvantages of the two alternative solutions.
Grøft-OV200mm.sfi (Trench-OV200mm.sfi)¶
We define the trench with road parameters (manual method) using the following tables:
- Surface descriptions
- Rock shelf
- Superstructure
To describe the foundation, we use the reinforcement layer in the Superstructure table. Here we enter the desired value in the reinforcement layer column for surface 1.01 and -1.01.
In the template, we have entered a reinforcement layer value of 0.15.
To describe the rest of the trench surfaces, we use the Road surface layer in the Surface descriptions table. It is also possible to enter a rock shelf width in the Rock shelf table. No rock shelf is defined in the template.
In the template, Road surface (reference height 0.0) is defined as follows:
| Surface | Width (m) | Slope |
|---|---|---|
| 1.01 | 0.25 | 0 |
| -1.01 | 0.25 | 0 |
| 5.01 | - | 5 |
| -5.01 | - | 5 |
| 6.01 | - | 2 |
| -6.01 | - | 2 |
To describe the boundary between filling and backfilling, we use the Trench filling layer in the Surface descriptions table.
In the template, Trench filling (reference height 0.5) is defined as follows:
| Surface | Width (m) | Slope |
|---|---|---|
| 1.01 | 0.1 | 0 |
| -1.01 | 0.1 | 0 |
| ... | ||
| 1.02 | 0.15 | 0.5 |
| -1.02 | 0.15 | 0.5 |
| ... |
Grøft-OV200mmNy (Trench-OV200mmNew)¶
We define the trench with road parameters (manual method) using the following tables:
- Surface descriptions
- Rock shelf
To describe the trench surfaces, we use the Road surface layer in the Surface descriptions table. It is also possible to enter a rock shelf width in the Rock shelf table. No rock shelf is defined in the template.
In the template, Road surface (reference height -0.15) is defined as follows:
| Surface | Width (m) | Slope |
|---|---|---|
| 1.01 | 0.175 | 0 |
| -1.01 | 0.175 | 0 |
| 5.01 | - | 5 |
| -5.01 | - | 5 |
| 6.01 | - | 2 |
| -6.01 | - | 2 |
To describe the boundary between filling and backfilling, we use the Trench filling layer in the Surface descriptions table.
In the template, Trench filling (reference height 0.5) is defined as follows:
| Surface | Width (m) | Slope |
|---|---|---|
| 1.01 | 0.1 | 0 |
| -1.01 | 0.1 | 0 |
| ... | ||
| 1.02 | 0.15 | 0.5 |
| -1.02 | 0.15 | 0.5 |
| ... |
Furthermore, Trench foundation (reference height 0.0) is defined as follows:
| Surface | Width (m) | Slope |
|---|---|---|
| 1.01 | 1.0 | 0 |
| 1.02 | 1.0 | 0 |
Advantages and Disadvantages of the Templates¶
Sometimes there will be requirements for side coverage, while other times requirements for trench bottom width, see figure below.
A = Rock
An advantage of the Grøft-OV200mm.sfi (Trench-OV200mm.sfi) template is that the requirement for side coverage is satisfied whether the trench runs through rock or soil (since the surface starts at the top of the foundation and not at the bottom of the trench).
An advantage of the Grøft-OV200mmNy.sfi (Trench-OV200mmNew.sfi) template is that it will also handle rock shelf width in the foundation.
Creating Custom Templates¶
We can adapt the templates to other pipe dimensions, i.e., change the widths to fit and adjust the reference height for the layer. When we have adjusted the values to a new dimension, we must save them as a template. Use the Save template... function. We will then gradually get more and more templates that we can reuse on later projects.