Multiphase modelling of desiccation cracking in the near-surface of compacted soils

Stirling, RA; Davie, CT; Glendinning, S

doi:10.1680/ecsmge.60678

Multiphase modelling of desiccation cracking in the near-surface of compacted soils

Lookup NU author(s): Dr Ross Stirling, Dr Colin Davie ORCiD, Professor Stephanie Glendinning

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Abstract

© The authors and ICE Publishing: All rights reserved, 2015. The development of cracking as a result of desiccation is increasingly under investigation. The mechanical and hydrological behaviour of desiccated clayey soils is dramatically influenced, primarily by the preferential transmission of water. This may result in rapidly elevated pore water pressure and is widely cited as a mechanism for the strength reduction that leads to infrastructure slope failure. Continuum FD modelling has been undertaken using FLAC 2D in addition to the two-phase flow add-in enabling the unsaturated behaviour of the desiccated medium to be included. Factors affecting the incidence and scale of cracking observed in compacted clay fill have been investigated via a systematic sensitivity study. Such factors include the increase in material stiffness upon drying and parameters used in describing the soil-water retention curve. Where necessary, the influence of significant parameters has been established by means of a varied experimental program, this has given rise to the design, manufacture and testing of a laboratory test apparatus and procedure to define the tensile strength of compacted fills under varying saturation conditions. Through development of the model, desiccation, crack initiation and propagation have been simulated allowing the processes at the very near-surface to be successfully captured. The work is conducted in the context of ongoing research into the climate impacts on infrastructure slope management and contributes toward the improvement of existing slope hydrology understanding.