Experimental study on mechanical behaviour of fiber-reinforced clayey sand

Farhad Hassan Beigi, Abba Qhadimi, Mohammad Sharifipour, Mohamad Reza Habibi

In the proceedings of: GEO2011: 64th Canadian Geotechnical Conference, 14th Pan-American Conference on Soil Mechanics and Geotechnical Engineering, 5th Pan-American Conference on Teaching and Learning of Geotechnical Engineering

Session: Ground Improvement/Remediation

ABSTRACT: Experimental investigations and modeling of unconfined compression strength of fiber-reinforced clayey sand under static loading were conducted in this paper. The investigations include three aspects. First, a series of unconfined compression tests were carried out on specimens with different fiber and moisture contents. The effect of fiber and moisture contents on unconfined compression strength (UCS) and E were studied and analyzed. The results show that fiber insertion in clayey sand, cause an increase in UCS. Other results show that in moisture contents optimum and higher, the fiber insertion in clayey sand soil causes an increase in E and Role of fibers on the increasing of E in optimum moisture content is more sensible. Second, a function was introduced to describe UCS. The UCS was expressed as a polynomial power function of fiber and moisture content. Third, a function was introduced to describe E. The E was expressed as a linear power function of fiber and moisture content.

RÉSUMÉ: Ce document offre des études expérimentales et modélisation du sable argileux renforcé par des Fibres sous chargement statique dans le cas de compression uniaxial. Ces enquêtes comprennent trios aspects. Tout d'abord, une série d'essai de compression simple ont été effectués sur des matériaux avec différents valeur de Fibre et de teneurs en établis et analysés. Les résultats montrent dans les échantillons de sable argileux provoque une augmentation de E et le rôle des Fibres sur l'augmentation de E on teneur en eau optimale est plus sensible. a été exprimée comme une fonction puissance polynôme de la teneur en Fibres et de l'humidité. Troisièmement, une fonction a été produite pour décrire le module élasticité (E). dans ce cas, E a été exprimé comme une fonction linier de la teneur en Fibres et de l'humidité 1. INTRODUCTION In recent years, more and more geosynthetic materials have been introduced as engineering materials and widely applied in earthquake and geotechnical engineering. Geofiber is one of many types of synthetic materials being used to enhance engineering properties of soils by providing extra resistance of shear and tensile stress. Soil reinforced with geofiber can be considered as a composite material. Studies on mechanical behavior of soils with geofiber reinforcement are comparatively new when compared to other research fields. Various investigations on soils reinforced with short geofiber have been conducted by some researchers and manufactures. The roots of surface vegetation contribute to the stability of slopes by adding strength (Wu et al., 1988; Ekanayake and Phillips, 2002; Greenwood et al., 2004; Danjon et al., 2007). Monotonic loading in shear box tests, consolidated and drained triaxial compression tests have shown that shear strength is increased and post-peak strength loss is reduced when discrete fibers are mixed with the soil (Gray and Ohashi,1983; Maher and Ho, 1994; Yetimoglu and Salbas, 2003; Ibraim and Fourmont, 2007, among others). The important influence of fibre orientation on the mechanical response of fiber reinforced soils has been experimentally investigated in tests with controlled orientations of fibers (Palmeira and Milligan, 1989; Micha1owski and Cermak, 2002). Triaxial compression tests under drained and undrained conditions indicate that the shear strength parameters of the soil-significantly (Ahmad et al, 2010). Direct shear tests suggest that fibre inclusions introduce an apparent cohesion intercept to the soil in the dry state, which remains almost unchanged by an increase in water content. The peak friction angle was expressed as a function of the relative density of sand for both reinforced and unreinforced cases (Lovisa et al, 2010). Triaxial

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