CAN were employed to carryout stabilisation work along one side of this 500m long railway cutting in Wiltshire, which had a history of landslips and rockfalls The remedial works design requiring installation of 1700no. soil nails & rock bolts into the cutting slopes, and a facing system comprising 5500m2 of active rockfall netting.
With restricted access along the narrow crestlines, little space at the toe of the slope and limited possession availability the site posed a number of difficulties. To overcome the issue of limited possession opportunities, CAN designed and installed a bespoke safety catch fence at the bottom of the cutting during night-time possessions, using RRV mounted drilling rigs to drill the bottom row off soil nails which were used as the fence anchor points. This allowed all work on the slope to be carried out during the daytime with trains operating as normal.
As the cutting was 20m high, and plant access along the crest was restricted in areas, a combination of drilling methods were then devised to install the soil nails and rock bolts. Firstly excavator drill rigs, including long reach plant, were used to undertake drilling on the crest and upper slope, followed by installation a bespoke designed crest anchorage system. This allowed slope mounted drill rigs to be suspended on the face to drill the more inaccessible locations immediately above the catch fence, low down in the cutting.
CAN worked closely with the designers throughout the works, as unexpected ground conditions were encountered meaning that drilling methodologies and the soil nail design itself required adapting as works progressed. Overcoming the difficult access restrictions and these additional challenges, this £1.4m scheme was completed on programme.
Duration: 23 weeks
Client: AMCO Giffen
Location: Corsham, Wiltshire