DRAM: A three-dimensional analytical model for the mobilisation of root reinforcement in direct shear conditions

Gerrit Meijer, J. A. Knappett, Glyn A. Bengough, Daniel Bull, Teng Liang, David Muir Wood

Research output: Contribution to journalArticlepeer-review

4 Citations (SciVal)


Roots can stabilise slopes against shallow landslides by mobilising their mechanical strength. Existing analytical models are highly simplified and typically focus on the ultimate limit state only, thus providing little insight into the underlying mechanism of reinforcement mobilisation. A new analytical model (‘DRAM’) was therefore developed to predict mechanical root reinforcement as a function of direct shear displacements. This model accounts for elasto-plastic root behaviour, three-dimensional root orientations, root failure through breakage or slippage, and a dynamically changing shear zone thickness.

Comparison to two independent experimental direct shear data sets showed that the model was able to accurately predict the gradual mobilisation of root strength, the magnitude of peak root reinforcement, as well as the presence of significant root reinforcement at large shear displacements, associated with a relatively large quantity of roots slipping out of the surrounding soil.

Because the newly developed model more closely resembles the underlying physics of the mobilisation of root reinforcement in direct shear while still being easy to use, it will be a useful tool for the engineering industry, in terms of quantifying root reinforcement distribution for limit analyses at the ultimate limit state, as well as for directing future research into the drivers of mechanical root reinforcement.
Original languageEnglish
Article number106621
JournalEcological Engineering
Early online date25 Mar 2022
Publication statusPublished - 30 Jun 2022

Bibliographical note

Funding Information:
This research was funded by EPSRC grant EP/M020355/1 , which is a collaboration between the University of Dundee, the University of Southampton, the University of Aberdeen, Durham University and The James Hutton Institute. μVIS X-ray imaging work was supported by EPSRC grant EP/H01506X . The James Hutton Institute receives funding from the Scottish Government (Rural & Environmental Services & Analytical Services Division).


  • Root reinforcement
  • Direct shear
  • Landslides
  • Analytical modelling
  • Vegetation


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