Pipes for Pipe Jacking

[Ingseven]

Hi there,
do somebody knows if there is a difference between a pipe for jacking into sand using EPB TBM and without using EPB?
Thanks

 

[rconner]

I don't profess to know a lot about this field, but I suspect you are probably talking about "earth pressure balance" in the vicinity of the cutting face, in the context of tunnel boring (machine) operations etc. I do know the paper at

http://www.hatchmott.com/documents/...al-L.pdf#search="earth pressure balance pipe"

, under the heading “Modeling Earth Pressure Balance Effects”, contains the statement, “While this
has the beneficial effect of reducing surface settlements, it results in increased lining
loads in comparison to open mode tunneling methods.”

 

[Ingseven]

Thank you! You are right. But the article compares segmental rings (EPB TBM) and cut & cover pipes and not the differences in pipe loads when using EPB machines or machines without EPB.

 

[Dirtguy4587]

Are you looking at axial pipe loading (i.e. TBM advance-induced stresses) or ground pressure 'hoop' stresses?

EPB vs. non EPB should have little effect on the ground pressures exerted around the tunnel. However, when considering axial liner loading, the TBM must exert enough pressure to overcome the design Earth Pressures for EPB operation.

 

[cvg]

with EPB machines, practice may be to use minimal or no overcut to limit settlement, this results in potentially less soil loosening and full load transfer from the soil to the pipe. This may increase the jacking load. Reference Pipejacking and Microtunneling by James Thomson, 1993