DESIGN OF LARGE DIAMETER BURIED PIPES

April 18, 2022 by admin in Uncategorized

Anders Andtbacka, Peter Sejersen

# 2021 Amsterdam

In the late nineties a study of the behavior of buried thermoplastics pipes was carried out. The project had input and participants from both the plastic pipe industry as well as from external organizations. Six external leading experts in the field of pipeline design, not necessarily plastics pipes design, have been involved as consultants in the project. The experimental work included a number of less ideal installation circumstances, in order to fully understand where the border line of safe installations is. A report that summarized the experimental work carried out was issued including an analysis of the pipe soil interaction process as it was monitored during the study. Next to that, a simple design graph explaining the short and long-term deflection as a function of the pipe stiffness class and the quality of the installation. The results have been presented at the plastic pipe conference as well as it is being used in standardization work, e.g. in developing CEN TS 15223, “Validated design parameters of buried thermoplastics piping systems”. Although the physical rules stay the same the world has changed. The need for watertight solutions in large diameter sewer pipes has given plastic pipe solutions a significant increase in market share in Europe, very well supported by the introduction ofthe EN 13476 standard which describes a number of different ways to design and produce a structures wall pipe. TEPPFA has therefore decided to extend that Buried Pipe Study by adding field tests and measurements of large diameter structured wall pipes in order to enhance the scope. A test field in Denmark has been used and SN2 and SN4 PE pipes according to EN13476 have been installed under “Good”, “Moderate” and “Poor” conditions. The soil used has been poorly grated sand and silt mixture which allows the poor installation. Cover depth is one meter. The deflection has been measured after assembly but before backfilling, after backfilling up to the crown, after completion and after 3 weeks, three months and eighteen months. Other test installation in Finland and Sweden has been included in the project, all of them affected by severe traffic load. The conclusions of the studies have resulted in confirmation of the validity of the TEPPFA graph for large diameter pipes: pipes up to 3000mm in diameter. Furthermore, a new calculation tool has been launched. This tool can be used when the installation parameters are outside the scope of the established parameters.

article source: https://www.pe100plus.com/PPCA/DESIGN-OF-LARGE-DIAMETER-BURIED-PIPES-p1741.html