
How to and with what to backfill the voids of shoring?
Hi, a soil improvement is being made for a shallow foundation as shown in the diagram (walers, props and timber planks not shown for clairty).
Solder piles are to be removed once backfill is complete. It would not be much of an issue for footings placed on normal soils, but as this is a soil improvement situation and the railway track is adjacent, I think the voids might give way for the footing to settle. Hence the thought of backfilling the voids with an appropriate material once the verticals are pulled out, before loading the footings.
So the two questions are whether backfilling is needed or not and if yes, what to backfill with and the methodology)... Any and all input on this is appreciated. TIA!
P.S. GWL is at around -2m.
Update:
Railway would not be used during construction and shoring members are sized for train surcharge anyways.
Grout injection is not reliable in my country. Micro piling is our preference but based on previous experience on another sector of the project, the consultant is a headache to work with when it comes to piling.