Lancashire-based ground improvement and piling specialist Pennine has developed a modified vibro compaction technique that it claims works in alluvial clay and organic peat strata – materials normally not considered appropriate for treatment by vibro methods.
The solution has been developed for contractor Birse at the Nar Ouse Regeneration Scheme at Kings Lynn, and is currently being used to stabilise ground along a 1.8 km section of the new A47 single carriageway spine road in a scheme incorporating the construction of a new River Nar Bridge, Culvert, Puny Drain Bridge and retaining walls.
It uses traditional vibro techniques but, to keep peat disturbance to a minimum while inserting the VCCs and VSCs, Pennine has adapted its rigs to enable water to be flushed down the borehole at the same time as the poker is being vibrated into the ground.
The water then saturates the peat, keeping it in place as the poker pushes through.
“We have already tried and tested the new solution with great success,” said founding partner Andy Russell. “We are confident that we have found an answer to the long-standing geotechnical problems experienced in many areas of the UK, particularly in the South and East of England.”
Russell said: “Tests of our ground improvement scheme have showed significant cost and program savings. It has not only improved drainage of the areas, speeding up primary consolidation of the ground from 20 weeks to 12 weeks, but some secondary consolidation has also been recorded.”