The mechanics of fibre-reinforced sand

Abstract

Fibres can be an effective means of reinforcing soils. This paper presents data from laboratory triaxial tests on quartzitic sand reinforced with polypropylene fibres. By keeping the studied composite consistent throughout the study (host sand and fibre characteristics kept constant), it has been possible to develop a framework of behaviour for the sand-fibre material, which provides a solid base for future research on fibre-reinforced soils. Data from previous work and from new tests have been analysed within the Critical State framework, that is in terms of normal compression line, critical state line and state boundary surface. KEYWORDS: laboratory tests; reinforced soils; sands Les fibres sont parfois un moyen de renforcement efficace des sols. La présente communication présente des données issues d'essais triaxiaux en laboratoire sur un sable quartzique renforcé aux fibres de polypropylène. En maintenant l'homogénéité du composite étudié tout au long de l'étude (en maintenant constantes les propriétés du sable hôte et des fibres), il a été possible de développer un cadre de comportement pour la matière sablefibre, qui constitue une fondation solide pour une recherche future sur les sols renforcés à la fibre. On a analysé des données provenant de travaux précédents et découlant d'essais nouveaux dans le cadre de l'état critique, autrement dit sur le plan de la ligne de compression, de la ligne de l'état critique, de la surface limite de l'état.

A behavioural framework for fibre-reinforced gravel

“…This is not the case for the fibre reinforced specimens, for which the stress ratio at zero dilation and the slope of the stress-dilatancy relationship at higher rates of dilation are significantly different. Similar results have been reported by, for example, Michalowski and Cermak (2003) and Dos Santos et al (2010).…”

“…In other words, the addition of fibres interferes with the packing of the grains. This was also observed by Michalowski and Zhao (1996), Ibraim and Fourmont (2007), who attributed it to the greater resistance to compaction in the presence of the fibres, and by Dos Santos et al (2010).…”

“…However, previous researchers have interpreted the effect in two different ways: (1) the higher apparent stress ratio at zero dilation indicates an increase in the underlying fundamental steady or critical state strength (e.g. Dos Santos et al, 2010); and (2) the critical state stress ratio of the granular matrix at zero dilation does not change, but the stretched fibres increase the lateral stresses in the granular matrix, permitting a higher axial stress so that the apparent stress ratio increases (e.g. Diambra et al, 2013).…”

Effects of random fibre reinforcement on the density of granular materials

“…The addition of fibres delays dilation as shown in the volumetric strain plots. This corroborates the findings of Michalowski and Cermak (2003) and Dos Santos et al (2010). Diambra et al (2013) however reported an increase in the dilation of specimens reinforced by thread-like fibres.…”

On the Strength of Fibre-Reinforced Soils

“…There is signiˆcant experimental evidence that the failure envelope of aˆbre-reinforced soil is non linear (Consoli et al, 2007a;Santos et al, 2010). In the case of a bilinear schematisation, which is often adopted to represent this non linearity, the normal stress at which the slope of the envelope changes is deˆned as a`critical normal stress' (s n, crit ) and grossly represents a change in thê bre to grain interaction mechanism.…”