How do customers design a PE pipe to resist external loads e.g. traffic, soil and seismic loads?
Plastic pipes, including PE100 pipes, are normally classed as flexible pipes in structural terms and hence their design to resist external loading is different from that of rigid pipes such as steel, ductile iron, concrete, etc.
The action of the vertical external loads, e.g. traffic loads, causes the flexible PE pipe to deflect. The deflection is resisted by the passive horizontal soil pressure acting on the pipe.
This means that the bedding and stiffness of the surrounding soil are considered as important as the mechanical properties of the pipe when traffic loading is being considered.
A number of models have been developed by the industry to allow the designer to specify the correct pipe and soil properties. The TEPPFA model is currently under revision.
A general method of calculating soil loading on flexible plastic pipes and designing to provide the necessary resistance and safety factor has been developed by TEPPFA. This is at present being updated and revised.
Current information can be found at www.teppfa.com