CIRIA’s Research Project 441 'Field trial and demonstration site for bio-engineering', undertaken over the period 1991-1995 and Research Project 536 'Bioengineering: M20 - medium-term monitoring', from 1995 to 1998, followed from CIRIA’s earlier publication, B10 The use of vegetation in civil engineering. The project was conceived as a live trial, where the effects of vegetation on the stability of slopes could be demonstrated for the benefit of the engineering community and its clients. The research was not able to continue at Longham Wood as the site was taken over by the route of the Channel Tunnel Rail Link in mid-1998. This report supersedes CIRIA Special Publication 128, Bioengineering: a field trial, and covers the following aspects of the project:

literature review to establish the required geotechnical attributes and vegetation types

setting up of the site, on a reprofiled cutting in Gault Clay, adjacent to the M20 in Kent

the instrumentation installed to monitor the hydrological characteristics of the site

the tests carried out to monitor the geotechnical and vegetation characteristics

final exploration to calibrate instrumentation and to determine the extent of root growth and effect on ground conditions

the effects of the vegetation on the calculated factor of safety of the slope

the results of the monitoring and testing and conclusions to be drawn.

The open publication will be supported by a large volume of numerical data, collected during the monitoring periods. This data will be presented in a separate Data Appendix, which will be separately available from CIRIA on CD-ROM.

Key words: ground engineering, materials, transport infrastructure.

ISBN: 978-0-86017-881-1
Author: J R Greenwood et al
Number of pages: 128 (paperback)
Publisher: CIRIA
Date of Publication: February 2001