Tunnel Reinforcement - Weldgrip Gripforce ® Rockbolts and Fibre Mesh

Project Title Bradway Tunnel Reinforcement Client Railtrack Main Contractor Amalgamated Construction Co. Ltd Featured Products Weldgrip Fibregrip ® Rockbolts and Fibre Mesh

The Bradway Tunnel maintenance project was part of the upgrading of the Midland Main Line rail network, and involved replacing a bulged area of the brickwork lining in the roof and sides.

To achieve this, a temporary support system was required to maintain the integrity of the brickwork. Weldgrip Fibregrip ® Rockbolts were used to offer a safe support system for the brick tunnel lining, enabling cutting out and replacement of the bulged brick section.

A high density of rock bolts was installed in the bulged area and placed through a polymer geogrid at 0.75m centres in a grid pattern. The Fibregrip ® Rockbolts used were 22mm diameter x 2m long, with a tensile and shear strength of 470kN and 129kN respectively. They were installed in 28mm diameter holes and spun through polyester resin capsules which had a cure time of 5 minutes.

A standard 80kN nut and a 150mm diameter round high load plastic end plate was used to tighten the bolt end assembly to the brickwork and polymer geogrid. The rockbolts were cut back to the tunnel lining as the bulge was removed and the brickwork repaired.

The Weldgrip Fibregrip ® Rockbolt system delivered the following advantages to the maintenance project:

• Safe method of working during installation
• Quick and effective method of reinforcing the bulged section of brickwork
• Lightweight construction of the rockbolts allowed easy handling during installation and removal
• High shear & tensile strength of the rockbolts gave excellent support to the brickwork in the bulged areas
• Weldgrip Fibregrip ® Rockbolt system provided a cost effective solution
• Cutability of the rockbolts allowed a quick method of removal as the brickwork was repaired

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Product Brochure - Soil Nails & Rockbolts - 620k

Weldgrip are also proud to have attained BBA accreditation and ISO 9001 standards in recognition of our continuing excellence in Geotechnical products and services.