Keywords: simulation, optimization, polyethylene pipes, buried pipes, process automation, graphical user interface.

Structured-wall high density polyethylene pipes up to 3.5m diameter are used extensively in civil engineering applications including storm water attenuation tanks, culverts, surface drainage, inter-process pipe work, sewers etc. A key quality control measure is the ringstiffness to BS EN 1446: 1996 [1]. The ability to predict this accurately as a function of the pipe wall geometry is a pre-requisite for optimization of the pipe design and during the manufacturing process. In addition to that, a thorough understanding of the pipe's behaviour during and after installation is of great importance. Thus, the accurate simulation of the ringstiffness test and the installation process for the buried pipes are vital in their design. Recurring design situations allow for an automation of many underlying tasks. A Java based graphical user interface (GUI) has been developed that allows for automated simulation and optimum design requiring minimal user interaction. For computationally expensive background calculations in-house FORTRAN and open-source software are incorporated into the tool.

This paper describes the structure and functionality of the GUI. The structure can be divided into three main categories: The creation of the finite element (FE) cross-section representation, the ringstiffness test simulation and optimization feature and the buried pipe simulation functionality.

After the theoretical background for the software developed has been given, two applications of the various features and the comparison of the results obtained to real life examples show the usability and validity of the software. In the first example a ringstiffness test is simulated using a shell element representation extracted from a laser scan and a rectangular box-section approximating it. Both results are shown to be sufficiently accurate. In addition to that a new profile geometry is created using the optimization feature. The new design requires 33% less material than the original one. A second example shows the application of the buried pipe simulation feature. Displacement measurements taken during the installation of a system of 15 pipes are sought to be reproduced. Eight different simulations are run varying the height of cover, the location of the pipe within the trench, the quality of the soil compaction and the existence of additional external loading. Again, the obtained results are sufficiently close to the observed data.

1

British Standards Institution, "BS EN 1446:1996 Plastics piping and ducting systems - Thermoplastics pipes - Determination of ring flexibility", British Standards Institution, London, 1996.

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