Support
Pressure network at a fixed depth and trench volumes
Summary
To draw a pressurised water distribution network at a constant depth below the terrain (1 m, for example) there is no need to enter the data node by node: the network is generated from 3D polylines projected onto an offset copy of the terrain surface. This article describes that procedure, how to obtain the excavation volumes afterwards by means of the trench section, and what limitation the Networks module reports have when exporting to Excel.
Applies to
MDT 9, MDT 25 and MDT26 — Networks module. The procedure is the same in all three versions; the documented case is based on MDT 25.
Networks functions (generating pipes from 3D polylines, trench sections and reports) and Surfaces functions (copying, offsetting and projecting).
Symptoms
You want to design a pressurised water distribution network at a fixed depth below the terrain (1 m, for example), without entering the data node by node, and show it on a longitudinal profile.
You need to obtain the earthwork volumes for the excavation of the network.
You need to export earthwork tables to Excel with cuts at fixed distances.
Cause
This is not a program error, but the way the Networks module works: the network is designed on 3D polylines, so the depth below the terrain is obtained by offsetting and projecting surfaces, not by entering each node by hand. The volume calculation, in turn, requires each pipe or collector to have its trench section applied.
Solution
Case: pressure network at a fixed depth below the terrain
To design a network at a fixed depth below the terrain (1 m, for example) without entering the data node by node:
Copy the terrain surface and offset it vertically downwards by the required depth (1 m, for example).
Project the network polylines onto that offset surface, so that each vertex takes the corresponding elevation.
Generate the network pipes from those 3D polylines. The network is then at the fixed depth below the terrain and can be shown on the longitudinal profile.
Excavation volumes: to obtain the earthwork volumes you must apply the trench section or sections to each pipe or collector. Once the depths are defined, the Networks module calculates the theoretical excavation volume and the backfill by layers, taking the type of pipe into account. The analysis is carried out pipe by pipe, treating each segment independently.
Reports to Excel: the Networks module can extract several reports (with elevations, depths and options for setting out or analysis) to be processed in Excel. However, it does not allow fixed cut distances to be specified in order to generate the earthwork table.
If the problem persists
If you need an earthwork table at fixed cut distances, bear in mind the limitation of the Networks module described above; to consider alternatives, contact Aplitop technical support describing the type of network and the output you need.
If the network does not end up at the expected depth, attach your drawing when opening the enquiry so that support can review the offset surface and the projected polylines.
Category: Sewerage and utility networks · Level: Intermediate