There's a piece in the January Modern Railways, p. 17, saying Manchester-Preston delayed by foundation problems for masts including old mine workings and running sand. "Network Rail says it has now found innovative solutions. ... One such solution involves a steel cylinder being inserted into the ground to act as a support, preventing ground collapse. A big drill then removes the soil from within the steel casing and the cylinder is filled with concrete. Additional weekend blockades will be needed to keep the project to time."
I thought that was a standard method of piling anyway.