Crusader Avenue, Glasgow – Permeation Grouting

Project Summary

Soil Engineering were appointed by The Coal Authority to undertake permeation grouting to stabilise the granular overburden (sands & gravels) at the Crusader Avenue site following the consolidation of two mineshafts.

Soil Engineering Solution

The sensitive positioning of the site and the proximity to occupied residential properties required minimal disruption to local residents and reducing the overall environmental impact of the works were of top priority.

Prior to commencement of the works it was agreed with The Coal Authority that the site surface should be re-graded, vegetation removed and a run-off catch ditch excavated along the bottom edge of the site to contain run-off from the drilling and grouting works. The works were designed in conjunction with geotechnical specialists from The Coal Authority.

The ground stabilisation work comprising 60 No. boreholes to 21 m depth (just into the bedrock) on a 3 m centre grid around the two shafts was then commenced. Each borehole was subject to ascending stage permeation grouting in 3 m lifts with pressurisation according to overburden pressure.

Work was carried out in a generally inward spiralling manner to reduce the risk of tracking and working over any buried cavities in the drift deposits that may have still existed. None were in fact detected although some significant grout takes in the drift and recently placed stone in-fill were recorded. It was also noted that grout often surfaced several metres away from the injection hole across the middle of the affected area. In total 40 tonnes of cementitious grout was injected across the site.

The work was carried out using 2no Boart Longyear rotary percussive rigs and restricted access pressure grouting systems.

The site was managed and completed by a team of 6 direct employees of Soil Engineering’s Ground Engineering Services department.

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