Abstract
When it was constructed at the turn of the nineteenth century the 5.2 km long Standedge tunnel on the Huddersfield Narrow Canal in the north of England was the longest in the world. It remained in constant use until its closure in 1944, but since then has fallen into disrepair. In 1999 a major contract was let by British Waterways to renovate it completely and return it to public use as a recreational amenity.
To design the rock support needed for stabilization the unlined and partially lined sections of the tunnel were divided into five structural zones. A rock structure interaction analysis of these zones and a kinematic assessment of likely discontinuity wedge failure modes were used to establish rockbolt lengths, patterns and capacities and sprayed-concrete specifications; four main support types were prescribed on this basis. The repairs carried out where the original masonry lining had been damaged, the crown had collapsed or the invert had been affected by heave are also described.
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