Solution for fill under an old bridge
Solution for fill under an old bridge
(OP)
We have an old single span road bridge which was assessed and considered to be weak. As the railway line under the bridge is dismantled, one of the options is to fill up the structure with fill material and pumped concrete to provide continuous support to the bridge deck. Subsequent to the closure of railway, the bridge has been partially infilled from one side (west side) and a car park has been built on top of the fill and in the level of the road (See attached drawing). So the access to the area under the bridge is only available from the east. We do not have any rights to work from the car park in the west.
We intend to access from the east and dig the fill material 1m in the whole width of the bridge, compact the ground and fill it with concrete.
My question is how can we retain the soil next to the car park from under the bridge with this limited headroom? Any solutions?
Please refer to the attached drawing for more details.
Thanks
We intend to access from the east and dig the fill material 1m in the whole width of the bridge, compact the ground and fill it with concrete.
My question is how can we retain the soil next to the car park from under the bridge with this limited headroom? Any solutions?
Please refer to the attached drawing for more details.
Thanks
RE: Solution for fill under an old bridge
There may be other ways and I haven't had my coffee, but that's what comes to mind.
f-d
¡papá gordo ain't no madre flaca!
RE: Solution for fill under an old bridge
If you need to support this existing car park fill / wall while you are overexcavating, then you may be better off demolishing the bridge anyway
RE: Solution for fill under an old bridge
In that case, there are many different options. I'd explore them before doing what you have planned.
One would be to drill through the deck and then use compaction grouting of the existing fill to compact it somewhat. That would also provide support to the nearby park fill. Chemical grouting is another way to solidify that old fill. This treatment also could wait until all is filled, depending on details.
Getting new fill into the under-deck area then can be by may means. One would be by belt conveyor, such as that used to pile aggregate into piles.
Another way is to use sand and large "conveyor" pipes and compressed air to blow it in there.
Final work would be compaction grouting of what you have placed, with pipes through the deck or pushed in horizontally.
If you still wish to fill with concrete, before you do that, install compaction grout pipes into the existing fill so you can pump in there later. I've even used ordinary downspout pipes for roof drains for this purpose. After concrete has set, go to it to compact that fill under the concrete with injected grout via those pipes. A concrete pump with a sand - cement mix works also. You don't need high pressure for your job.
I am sure others here have some ideas.
RE: Solution for fill under an old bridge
The car park fill is not supported now and there is no retaining wall. The fill has a slope of about 45` which goes under the bridge.
The reason we want to dig first is that the fill material is very poor and is mostly rubbish. So we want to dig it first, compact it, and then fill it up to avoid future settlements.
But now I should go through the options oldestguy suggested. In the meantime, I would appreciate other new solutions.
RE: Solution for fill under an old bridge
Maybe the tyranny of Murphy is the penalty for hubris. - http://xkcd.com/319/
RE: Solution for fill under an old bridge
RE: Solution for fill under an old bridge
I've seen them do some amazing things, (and some unexpected things, like filling sewers or tilting in basement walls).
Now let's say not everything is done perfectly and eventually the bridge settles or sags in the middle. It probably will not cause an accident, but it likely can be raised with slab jacking methods, should that ever happen.
Get the grouting guy there early for his practical ideas before going further. Be sure to have them furnish references of past good jobs. Not just anybody can do what you will need there.
RE: Solution for fill under an old bridge
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RE: Solution for fill under an old bridge