Reference standards
BS 8081:2015 – Code of practice for grouted anchors, BS EN 1537:2013 – Execution of special geotechnical works: Ground anchors, BS EN 1997-1:2004 (Eurocode 7) – Geotechnical design, Part 1: General rules, BS 5930:2015 – Code of practice for ground investigations, BS EN ISO 22477-5:2018 – Geotechnical investigation and testing: Testing of geotechnical structures, Part 5: Anchor testing
Quick answers
What's the typical cost of an anchor design package for a Wigan project?
For a standard design package covering temporary and permanent anchors for a single retaining wall in Wigan, fees range from £780 for a straightforward scheme with accessible ground data to £2,600 for a more complex assignment involving multiple anchor rows, DCP specification, and load test supervision.
How do abandoned coal mines in Wigan affect anchor design?
Abandoned mine workings, especially in the Pemberton and Ince areas, can cause sudden grout loss during anchor installation. We address this by specifying pre-injection grouting to fill voids and by designing the fixed anchor in competent sandstone below the worked seams, confirmed through pre-construction rotary drilling.
What corrosion protection level is required for permanent anchors in Wigan?
Given the acidic mine water (pH often 3.5–5.0) and high sulphate content in Wigan's Coal Measures, we mandate double corrosion protection (DCP) for all permanent anchors, comprising epoxy-coated strand, corrugated HDPE sheathing, and factory-injected cement grout, in accordance with BS EN 1537 and BS 8081.
Can anchors be used in Wigan's alluvial soils near the River Douglas?
Yes, but the bond zone must be designed with caution. The soft alluvial silts and clays near the Douglas floodplain exhibit significant creep under sustained load, so we extend bonded lengths, specify post-grouting techniques to improve bond, and run extended creep tests to verify performance before lock-off.
What load testing do you perform on anchors in Wigan?
All temporary anchors undergo acceptance testing to 1.25 times the working load. Permanent anchors are proof-loaded to 1.5 times the SLS load, with creep monitoring over at least 30 minutes per load step. For critical structures, we also install permanent load cells for ongoing remote monitoring.
