PENNINE VIBROPILING has been awarded a £500,000 ground improvement contract at Tilbury in Essex.
The firm, working for Jackson Civil Engineering, is carrying out the work for the Fortress Distribution Park which is being developed by client the Port of Tilbury.
Ground conditions comprise a 17m thick sequence of soft and very soft clays and silts with thin organic and peat bands overlying medium dense sands.
Pennine proposed using a wet bottom feed technique, which it developed in Indonesia.The technique introduces the stone down the vibroflot while flushing with water, to ensure column integrity.
The same column diameters and settlement control as the full flushing wet technique can be achieved, Pennine says.
The wet bottom feed system, comprising a specially adapted vibroflot with a high pressure jetting pump, is being used to form some 4500 stone columns at Tilbury.
The 750mm diameter columns are being installed on a triangular grid to a depth of 8m.
Fully computerised rigs monitor quality control during both the penetration and construction phases.Dataloggers are downloaded daily and results printed on site and transmitted via laptop to Pennine's head office.