Ok, I have an sturctural engineering problem I am working on and I thought I would ask you folks for your opinons and procedures:
The problem. I need to jack/push a 8' pipe thru a wall aproximately 20' thick. The wall is made up of 4 arches, two stacked over two and the pipe needs to pass thru the bottom two. The bottom two is filled with rubble, the top are hollow. We can't have any movement of the structure. We do not want to lose alot of the rubble fill during the pipe installation, except for the pipe volume, even though the rubble is not belived to be structural. We are going to grout the rubble voids in the bottom two arches prior to pushing the pipe, but there is no backpressure, so there is no way to know if the entire rubble in the area of the pipe push is completely grouted.
I was thinking of drilling and pushing consecutively larger pipes, maybe 2' first, then a 4', then 6' then 8', each time either pushing the previous pipe out, or cutting it out , as the larger pipe takes it's place.
Do you engineers on here have any better methods for doing this? I am open fo any ideas.
8' diameter pipe going thru the wall. The wall is 20' thick. Rubble is loose construction debris, concrete brick ect. This is an aqueduct (in the top 2 arches) and thats how they built them back in 1900. Theres a road on top.
I understand the picture you've painted...i think. Does the job site allow you to pressure inject a concrete slurry on the exterior side walls of the arches? If you could, then inject, wait for 28 days or whatever the mud requires and then bore the middle. I'd also look at sleeving the outside walls where the pipe is to run thru the structural part of the arch wall on both ends and then run the drainage pipe thru that, weld it, and call it good. I would think a 12-18" deep sleeve would be enough. Obviously the sleeve is going to be the structural part that would be grouted as soon as the sleeves are in place, then the boring would continue thru the rip rap. Kapech?
That picture is right on with two more arches over it. Your desciption of the problem is dead nailed on. Guess 8 feet diamater pipe has confused alot of people, but that is correct. The pipe needs to flow alot of water.
Labnard, we will inject slury inside the arches to consolidate the rubble (and seal off any water that may be trapped inside), but there is no backpressure. When do you stop to and ensure the entire pipe penatration area is completely sealed. We may have to guess on this one and hope for the best.
Jack and bore will be used after rubble consolidation, with the boring part being men inside the pipe moving the debris. If the rubble is not too cosolidated, this could mean trouble. That is why I like the step process metioned in the intial post.
Keep in mind this is a Hundread year aqueduct, so it needs to not move during this operation.
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