Crag End Landslip, Northumberland | Piling Contractors | Keller UK

Crag End Landslip, Northumberland

Following a land slip that started on Boxing Day 2012 and worsened during the following winter and spring, the B6344 road at Crag End, had been closed to all vehicles and pedestrians.

Investigations have proven the ground conditions to be challenging, with artesian water conditions and highly fractured bedrock overlain by glacial till deposits containing significant boulders.

WS Atkins developed a solution involving permanent dewatering and a contiguous piled wall with permanent ground anchorages. VBA Joint Venture Ltd. were appointed to undertake the works, starting in Spring 2015.

Keller were contracted to install 436no. Bored Piles up to 26m in length, and 144no. Ground Anchorages up to 32m in length.

The piled wall design required a minimum 3m socket into underlying bedrock, and the presence of large boulders in the overburden made for difficult drilling conditions. A Bulroc CDS-R casing advancement system was utilised to install permanent 508mm diameter casing to bedrock, and a Bulroc Hyper 141 hammer was used to drill the 450mm diameter rock sockets. The system was used with Klemm 709-2 restricted access piling rigs, and where site constraints allowed, a larger Soilmec SF50 open site rig.

Ground anchors were installed with Keller Geotechnique’s bespoke Cat 315 anchor rigs to an in-house design.  140mm pneumatic down the hole hammers were used with temporary casing to advance the bores for installation of the three strand anchor tendons.

To ensure the seven-month programme was met, up to six rigs were utilised simultaneously from the extensive Keller fleet.

Systems: Bored Piling

                Permanent Strand Anchors

Client: Volker Stevin Ltd

Contractor: Keller Geotechnique

Engineer:  WS Atkins



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