A micro-mechanics based soil-fibre composite model for use with finite element analysis
Thomas Bower  1, *@  , Anthony Jefferson  1@  , Peter Cleall  1@  , Paul Lyons  2@  
1 : Cardiff University  -  Website
School of Engineering Cardiff University Queen's Buildings The Parade Cardiff CF24 3AA -  United Kingdom
2 : LUSAS  -  Website
Forge House, 66 High Street, Kingston Upon Thames, Surrey, KT1 1HN -  United Kingdom
* : Corresponding author

Inclusion of manufactured fibres into a soil has been shown to significantly increase its shear strength and modify its dilative behaviour. The primary mechanism for strength increase is due to the frictional interaction between individual fibres and soil particles. Each fibre resists the movement of soil around it and this has an overall effect of increasing the shear strength. This paper presents the initial development of a micro-mechanics based soil-fibre model which uses concepts from the well-known shear lag model and is extended to include fibre de-bonding. The distribution of fibre orientations is taken into account by use of a distribution function which can be modified according to different soil-fibre preparation techniques. The micro-mechanical model is homogenised using a spherical integration technique and inserted into a single point constitutive driver using the rule of mixtures. The hardening soil model was chosen as a matrix material for this study as it captures the non-linear stress-strain response and failure limit observed in triaxial compression tests. The proposed soil-fibre model is then compared against triaxial compression test data of a well graded sand with differing fibre contents of Loksand fibres and different confining stresses. Preliminary simulations of the experimental tests show promising results.

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