BE-13 Renovation: Lining with Cured-In-Place Pipes - Processes - v01

Static Proof

Host Pipe Condition III

Non Standardised statics - 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 CIPP 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. In contrast to the host pipe conditions I and II, the influences on the CIPP liner in host pipe condition III are generally much greater.

If one of the criteria given in the table is met, the pipe must be classified into the host pipe condition III and the above rules are no longer valid. Then an individual static calculation is required for the host pipe condition III according to worksheet DWA-A 143-2.

For sewers where an assignment to the host pipe condition II and host pipe condition III is not clear and unambiguous, the EMPLOYER decides on the assignment to the host pipe condition.

1. Host pipe
2. CIPP liner
h Cover above the pipe crown [m]
hW,So Height of the water level above the invert of the CIPP liner [m]
qv Vertical soil stress on the pipe [kN/m2]
qh Horizontal soil stress on the pipe [kN/m2]
 

Table: 

Criteria for classifying a sewer as host pipe condition III based on DWA-A 143-2.
Criteria Limit Value
 Joint ring deformation (ovalisation)
 greater than 6 %
 Cover over crown smaller than the cross-section width
 Change in load (e.g. increase in superimposed load yes
 Cracks are larger yes
 Cavitation in the soil due to infiltration
 yes

 

 

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