The New Garden of Eden built with Rock Bolts and Ground Anchors

At the end of the 90s, a 60m-deep former china clay pit just outside St.Austell in Cornwall was transformed into a unique 21st century Biosphere.

Context

The site, which has the size of 35 soccer fields, features two so-called biomes, huge greenhouses, each consisting of 4 interconnected domes. Like honeycombs these domes were connected with each other to form a curved natural space.

The domes are up-to-55m tall and shelter two climate zones: a humid tropical climate and a warm tempered environment. Geology on the site required stabilization of the quarry faces and tying down the foundation ring beam using double corrosion protected ground anchors.

Solution

The stabilization of the quarry faces involved the installation of over 2,000 DYWIDAG Rock Bolts and Soil Nails. In the harder sections conventional DYWIDAG Gewi Rock Bolts were installed with open-hole drilling.

Where softer bottom layers were encountered, a mixture of bolting and nailing was used with DYWIDAG Dywi Drill Hollow Bar Anchors. This system enables simultaneous drilling and grouting, ensuring injection of grout over the full depth of the borehole. In areas where the surface of the slope was unstable shotcrete tied back by rock bolts was used for additional face enhancement.

The greenhouse opened in March 2001.

Going Further

To facilitate the work on faces up to 12m above ground level, the drill platforms were mounted on telescopic hydraulic arms.

Supply

The Eden Project Main contractor

John Grimes Partner

Saxton Deep Drillers

JV McAlpine

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