CAN Geotechnical was appointed as subcontractor after a catastrophic failure event. It was in fact approximately 50m3 of rock which also led to a large (roughly 3-4 tonne) boulder landing in the four foot of the running line at the toe of the slope.
CAN attended site immediately and escorted a geotechnical engineer on to the site. An inspection was carried out of the slope, to formulate a stabilisation solution. A week after the inspection, CAN mobilised to site on 16 Jan 2017.
CAN Geotechnical installed a line of top bolts and a temporary rockfall netting drape over the area where the main failure had taken place. This allowed for a safe installation of the permanent design to take place, and temporary protection for the track below.
A total of 51 rock bolts were installed in the immediate failed area overlain with TECCO G65/4 with extra face cables to help the mesh conform to the contours of the slope. Additionally Hydroseeded hessian matting was added to further help with the process.
Following the stabilisation of the rock face, CAN broke up the large blocks of rock at the toe and removed them from site, along with any other rocks and debris along the whole length of the catch ditch. The existing catch fence at the toe was also reinstated.
Following the successful construction of the failure area, CAN was then instructed to stabilise the rest of the embankment.
This included over 200 additional rock bolts, up to 12m in length and an additional 1800m2 of TECCO G65/4.
Due to the fractured and voided nature of the limestone, CAN Geotechnical utilised mist flush techniques and grout socks. This was in order to produce a clean hole and prevent the grout from migrating too far away from the hole.
CAN demobilised from site in August 2017.
Duration: 8 months
Location: Chalford, Stroud