Tensar stabilisation technology

Tensar stabilisation technology prevents highway mine subsidence with cost and time savings.

After years of disuse, reviving the Stirling to Kincardine railway line will provide a better route for freight as well as passengers, with concurrent construction of a new road link.

However, near Alloa, a portion of the eastern link route and its interchange with the A907 could have been affected by subsidence due to underlying shallow mine workings.

By using Tensar International's Basetex high strength basal reinforcement geotextiles and aggregates to reinforce the overlying soils, the First Nuttall JV avoided the considerable potential time and cost of grouting the mines.

The soils along the northern bank of the River Forth consist of silty clays with a low bearing capacity and, in addition, the area has been extensively mined for coal, with three separate seams, and as little as 30 or 40 metres below the surface.

"The conventional method would have been to fill the mines with cementitious grout," commented Paul Abraham, Site Agent for First Nuttall.

"This could have taken considerable time and apart from the materials; the total cost might have been as much as four or five times as using the Tensar solution".

William Cannon of consultant engineers Donaldson Associates added: "Tensioned membranes are an accepted and proven solution for this type of application".

"Tensar were very helpful in supplying information to put together the proposal".

To stabilise the sub-grade for the new road and interchange and help minimise possible differential settlement, the solution comprised Tensar Basetex geotextiles, overlaid with imported Class 6F2 capping material.

Tensar Basetex is manufactured in a particular way that minimises the initial stretching under load which can occur with conventional woven yarns, allowing it to mobilise the maximum strength with the least deformation.

Client: Clackmannanshire Council Consultant Engineer: Donaldson Associates Contractor: First Nuttall, a Joint Venture between Edmund Nuttall and First Engineering.

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