Hollow Bars used to stabilize a steep cutting
The UK's first toll road is under construction around the northern and eastern edge of a conurbation near Birmingham, England and is scheduled for completion in January 2004.
The new road will be a 27 mile (45 km) long dual three-lane motorway and is being built to relieve massive congestion on the nearby M6 motorway. Officially titled the "Birmingham Northern Relief Road", the road is now referred to as the "M6 Toll". Generally speaking, the side slopes to the M6 Toll are gentle gradients but, where the new road runs adjacent to a cemetery, it has been necessary to construct a steep cutting 150 m long x 8 m high which required stabilizing.
For ease of installation in soft ground conditions where boreholes produced by normal drilling methods would not stay open, the slope was reinforced by ten rows of permanent R32 DYWI® Drill Soil Nails. Approximately 1,000 of the soil nails in lengths from 7.5 m to 9.0 m were installed through sandy gravels and into weathered strata of the Mercia Mudstone Group, using the simultaneous grout injection technique to ensure efficient grout cover along the full length of each nail.
For permanency, a combination of hot dip galvanising and epoxy-coating was specified to achieve a design life of 120 years. A sprayed concrete covering was applied to complete the works.