Keller is installing 2,500 piles as part of an £18M scheme to stabilise a World Heritage Site.
Precious: The work is being carried out in a World Heritage site
Jackfield is a World Heritage site near Telford, in Shropshire, with a long history of slope instability dating back to 1883.
There were a number of severe events in the early 1950s, and in 1952/3 several properties and a road were lost into the River Severn. Since then, development and road construction in the area has been restricted.
The area, which sits in the Iron Bridge Gorge, has played an interesting part in the history of industrial Britain, as a centre for tile making and mining area.
One of the major issues, which has probably aggravated the slope stability over the years, is the former mine workings. These have been infilled with cement PFA grout.
“This innovative solution will enhance slope stability significantly”
Andrew Davison, Keller
Recent monitoring established that the slope was still active and that a further major slip could severely threaten upstream flooding.
As a result, Telford and Wrekin Council (TWC) engaged Jacobs to design a stabilisation solution.
TWC and Jacobs’ plan requires the installation of 600mm diameter continuous flight augur piles arranged along nine discrete corridors.
The piles are about 14m long, bored through the failure zone into the mudstone, and reinforced with a 457mm diameter steel tube.
Keller is using Soilmec R625 and SR80 rigs on the £3.5M contract to drill through the mudstone and, after concreting the piles, the 457mm diameter steel tubes are carefully plunged into the wet concrete.
A further 647, 250mm diameter piles, each reinforced with a 139.7mm diameter steel tube, will be installed along the river bank using smaller rigs.
“With a horizontal spacing of 0.6-1.75m, this innovative solution will enhance slope stability significantly,” explains Keller piling manager Andrew Davison.
“TWC is carrying out pile monitoring at a number of locations, using precise surveying and vibrating wire inclinometers installed by Keller.
“It’s clear from early readings, that movement of the slope, which can vary according to rainfall, is now reduced,” says Davison.
You might also like...
One off £30M charge dents Keller's rise in profits
Keller’s half-year results have been overshadowed by a £30M exceptional charge for a disputed contract. The firm posted a £32.5M pre-tax profit for the first six months of 2014, a 21% increase on the same period last year - but this will be almost wiped out by the charge, which centres on a project that Keller’s UK business completed in 2008.
Controversial Tintagel Castle bridge receives record donation
A £2.5M private donation has been made to English Heritage for the construction of the controversial Tintagel bridge in Cornwall.
Highways contractors sought for £630M works
Hampshire County Council has issued prior information notices seeking contractors to apply for works as part of a series of frameworks worth £630M for Hampshire, including the cities of Southampton and Portsmouth, the South West and the South East of England.
Detailed Stonehenge tunnel plans unveiled
Detailed plans for the proposed £1.6bn, 2.9km long, tunnel which will take traffic away from the A303 close the Stonehenge World Heritage Site (WHS) have been released. The scheme now awaits a decision on its development consent order (DCO) application.
Challenges of redeveloping Fulham's Thames-side stadium
WSP has revealed the difficulties in tackling the redevelopment Fulham FC’s Craven Cottage stadium.
Have your say
You must sign in to make a comment
Please remember that the submission of any material is governed by our Terms and Conditions and by submitting material you confirm your agreement to these Terms and Conditions. Please note comments made online may also be published in the print edition of New Civil Engineer. Links may be included in your comments but HTML is not permitted.