When - February 2013
Where - Near Arrochar, Scotland
Project Name - Rest and Be Thankful
Rest & Be Thankful are the words which are located on a stone near the junction of the A83 and the B828, placed there by soldiers who built the original road in 1753, and the road has been known by the same name for centuries.
After the road had been forced to close six times during the past five years following incidents when heavy rain washed tonnes of debris down the hillside and damaged the road, the Scottish Government drew up plans in 2012 to upgrade the old military road for use by all traffic as an emergency bypass in the event of future blockages. Traffic would only use the route under a convoy system.
Contractor
Rope Access Scotland Ltd were successful in winning the bid to install soil nails in an area that had suffered from landslides in the past between the new A83 and the Old Military Road below. The work was critical to ensure the Old Military Road stayed open should the A83 above be closed for any reason.
Materials
Having used SEA Construction on projects before and being confident with the quality and cost effectiveness of the products, it was an easy decision for Rope Access to make in electing to work with SEA Construction. It wasn't straightforward though as there would be three to four meters of rock to penetrate in places!
The following products were installed:
SEA SN32 Galvanised threaded hollow bar, 680 series. This bar is the lightest available and greatly improved on-site logistics which are important when having to maneuver on a steep slope! The reduced weight is achieved using less material but a stronger 680 'Yield Stress' material. Offering a minimum 'Yield' of 245kN the bar also has an increased internal diameter of 24mm which improves grouting rates. Even travelling through solid rock for 3 to 4 meters, there were no bar breaks, bends of deformities to any of the bars. An testament to the quality and strength of the bar.
SEA SN32 680 Galvanised Coupler. Made of the same, strong, 680 Yield Stress material, the couplers performed without incident and were praised by the operators on how strong and how little grout loss there was. There were times when the couplers were used to drive off which is an indication of the strength of these items.
SEA SN32 Tungsten Thor Drill Bit. These ground conditions were made for the Tungsten Thor and again, they didn't disappoint. The operators were extremely impressed by the ease in which they penetrated the rock and how they continued to work efficiently until depth was achieved.
SEA SN32 Galvanised Dome Nut. With the exaggerated dome on the SEA nut, achieving the angles of articulation was easy. In addition, the galvanising on the bar and the nut, with strict tolerances between the two, ensured the nuts went on easily. Maybe not a major issue having to tighten a nut with Stilsons but when there's several hundred, being able to 'spin' the nut on saves time, energy and ultimately money.