Wednesday 15th September Lunch time workshop – Structural calculation of Liners according to DWA-A 143-2
The DWA Method applies to the static calculation of liners and installation methods with any cross-section. The revision and transformation into a generally accepted engineering rule became necessary in particular due to the concept of partial safety factors for the actions (loads) and resistances, which was introduced with EuroCode 1. Another reason was the new regulation for heavy goods traffic applicable to bridge construction.
The presentation shows the basic procedure for the structural analysis of liners according to worksheet A143-2 of the German DWA. Among others, the following are addressed
- Pipe soil system - Host pipe conditions (HPC)
- Host pipe condition I: The host pipe is able to bear the load alone. In this case, the liner only has to ensure sewer tightness.
- Host pipe condition II: The host pipe alone is not able to bear the load and has longitudinal cracks at four points on its circumference.
- Host pipe condition III: This host pipe condition corresponds to host pipe condition II with the crucial difference that the stability of the host pipe-soil system is no longer verifiable. In this case, the liner has to bear not only groundwater loads, but must at least partially help to cope with all influences, such as soil, traffic and superimposed loads.
- Host pipe condition IIIa (informative only): host pipe deteriorated beyond host pipe condition III, fragmented and not able to transmit forces in joints. Liner must be designed as a new installed pipe taking special consideration in account.
- Load models and their superposition
- Partial safety concept
- Approval: Stresses, deformations, soil limit stress, stability, inner pressure, uplift, dynamic proof and if time permits, a live calculation example will be presented.