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Helical piles are used increasingly to support new and existing foundations. This paper presents a field study on the axial monotonic and cyclic behaviour of steel fibre-reinforced helical pulldown micropiles. Test piles consisted of a round corner square helical pile with three helices attached to it, and a steel fibre-reinforced grout shaft. To assess the grout shaft contribution, one helical pile without a grout shaft was tested. Piles were instrumented with strain gauges to evaluate the load-transfer mechanism. This paper discusses the load-displacement response of this pile system, and load-sharing mechanism between the grout shaft and lead section. The study shows that the grout shaft significantly improves the helical pile axial performance. It was found that the load-transfer mechanism within the lead section is through individual bearing of each helix. Also, the findings demonstrate that the behaviour of this pile system is satisfactory under one-way cyclic loading conditions. The results suggest that the reinforced helical pulldown micropile is a viable deep foundation option for axial monotonic and one-way cyclic loading applications. Key words: reinforced helical pulldown micropiles, full-scale field testing, monotonic and cyclic loading, load- transfer mechanism, pile capacity. Les pieux helicoidaux sont de plus en plus utilises pour supporter des nouvelles fondations et des existantes. Cet article presente une etude de terrain sur le comportement axial monotonique et cyclique de micro-pieux helicoi'daux anticalage renforces par de la fibre d'acier. Les pieux d'essais sont faits d'un pieu rond a helice carree avec trois helices attachees, et d'un arbre renforce d'un coulis de fibres d'acier. Afin d'evaluer la contribution de l'arbre avec coulis, un pieu helicoidal sans coulis a ete teste. Les pieux ont ete instrumentes avec des jauges de deplacement afin d'evaluer le mecanisme de transfert de charge. Cet article discute du comportement en charge-deplacement du systeme de pieu, ainsi que du mecanisme de partage des charges entre l'arbre avec coulis et la section principale. L'etude demontre que l'arbre avec coulis ameliore significativement la performance axiale du pieu helicoidal. Il est observe que le mecanisme de transfert de charge a l'interieur de la section principale se produit par la capacite portante de chaque helice. De plus, les resultats demontrent que le comportement de ce systeme de pieu est satisfaisant lorsque soumis a des conditions de charges cycliques en une direction. Les resultats suggerent que le micro-pieu helicoidal anticalage renforce est une option interessante pour les fondations profondes dans des applications de sollicitations monotoniques axiales et cycliques en une direction. Mots-cles : micro-pieu helicoidal anticalage renforce, essais de terrain a l'echelle reelle, charges monotoniques et cycliques, mecanisme de transfert de charges, capacite d'un pieu. [Traduit par la Redaction], Introduction A helical (screw) pile (HSP) is a deep segmented foundation system that consists of a relatively small galvanized central shaft fitted with one or more helices. The central shaft [...]

Concrete manholes are widely used in sanitary sewer and storm water systems in Canada. However, technical information regarding their structural aspects is limited. The main objective of this paper is to evaluate the effect of main parameters that impact the design of precast concrete manholes. A three-dimensional finite element model for circular precast concrete manholes was developed using Plaxis 3D and was calibrated against the experimental results presented in an earlier paper by the authors. The calibrated numerical model was used to analyze different configurations of concrete manholes and to conduct a parametric study on the parameters that govern its design including: type of native soil around the manhole; trench width ([T.sub.w]); water table elevation ([W.sub.t]); effect of manhole stage installation; and effect of soil compaction. The critical conditions were identified based on the change in the pressure underneath the centre of the manhole base and the bending moments within the manhole base. It was found that the trench width, stage installation of manhole, and filling soil compaction had marginal effects on the total vertical pressure beneath the centre of the manhole base. The presence of the water table at the top of the manhole resulted in the most critical contact pressure at the manhole base. Key words: precast concrete manholes, Ontario standard truck load, three dimensional finite element, bending moments in manhole base, strain gauges, pressure cells, soil structure interaction, water table and manhole trench width. Les trous d'homme en beton prefabrique sont largement utilises dans les reseaux d'egouts sanitaires et pluviaux au Canada. Cependant, l'information technique concernant leurs aspects structuraux est limitee. L'objectif principal de cet article est d'evaluer l'effet des principaux parametres touchant la conception des trous d'homme en beton prefabrique. Un modele par elements finis tridimensionnel pour les trous d'homme circulaires en beton prefabrique a ete developpe en utilisant Plaxis 3D et etalonne en utilisant les resultats experimentaux presentes dans un autre article. Le modele numerique etalonne a ete utilise pour analyser differentes configurations de trous d'homme en beton et pour realiser une etude parametrique des parametres qui regissent sa conception, dont: type de sol naturel autour du trou d'homme, la largeur de la tranchee ([T.sub.w]), l'elevation de la nappe phreatique ([W.sub.t]), l'effet du stade d'installation du trou d'homme et l'effet de la compaction du sol. Les conditions critiques ont ete identifiees en se basant sur le changement de pression sous le centre de la base du trou d'homme et les moments de flexion dans la base du trou d'homme. La largeur de la tranchee, le stade d'installation du trou d'homme et la compaction du sol de remplissage n'avaient que des effets marginaux sur la pression verticale totale sous le centre de la base du trou d'homme. La presence de la nappe phreatique au haut du trou d'homme a engendre la pression de contact la plus importante a la base du trou d'homme. Mots-cles : trous d'homme en beton prefabrique, charge de camion standard en Ontario, elements finis tridimensionnels, moments de flexion dans la base du trou d'homme, jauges de deformation, cellules de mesure des pressions, interaction solstructure, nappe phreatique, largeur de tranchee pour le trou d'homme. [Traduit par la Redaction], Introduction Literature on concrete sewer or storm water manholes is scarce and concentrates on durability issues (Griffiths and Ball 2000; Saricimen et al. 2003) or on the manhole performance as [...]

Circular precast concrete manholes are widely used in sanitary sewer and storm water systems. The lack of detailed technical information on them and the conservatism of their governing codes and standards call for a detailed investigation on them. The main objectives of this paper are to evaluate the state of strains in the precast concrete manhole and state of stresses in the soil beneath the base to be used in developing enhanced guidelines for the design of their bases. Three full-scale circular precast concrete manholes, two 1200 mm in diameter and one 1500 mm in diameter, were tested in the large-scale geotechnical testing facility (LSGTF) at the University of Western Ontario. Only one 1200 mm manhole base was reinforced. Twenty seven load tests were performed on the manholes, which involved loads representing the Ontario truck loads incorporated in the Canadian Highway Bridge Code. None of the manhole sections tested in the experimental program experienced any cracks. The test results showed that traffic loading had a small effect on the pressure under the manhole base. All three specimens could withstand the critical Ontario truck loads, even the non-reinforced ones. Key words: precast concrete manholes, full-scale testing, controlled testing environment, Ontario standard truck load, soil structure interaction. Les trous d'homme en beton prefabrique sont largement utilises dans les reseaux d'eegouts et de collecte des eaux pluviales. Le manque d'information technique deetailleie et le conservatisme des codes et des normes les regissant demandent une etude plus poussee. Les principaux objectifs de cet article sont d'evaluer l'etat des deformations sur le trou d'homme en beton prefabrique et l'etat des contraintes sur le sol en dessous de la base qui seront utiliseees pour etablir des lignes directrices ameliorees de conception de leur base. Trois trous d'homme circulaire a pleine echelle, deux d'un diametre de 1200 mm et l'autre de 1500 mm, ont ete mis a l'epreuve aux installations d'essais geotechniques a grande echelle (LSGTF) de l'Universite Western Ontario. Une seule base de trou d'homme de 1200 mm a ete renforceie. En tout, 27 essais statiques de chargement ont ete realises sur les trous d'homme; les charges representaient les charges des camions en Ontario incorporees au Code canadien sur le calcul des ponts routiers. Aucune section des trous d'homme mises a l'epreuve lors de ce programme experimental n'a monto des fissures. Les resultats des essais montrent que les charges causees par le trafic avaient peu d'effet sur la pression sous la base du trou d'homme. Chacun des trois eechantillons pouvait soutenir les charges critiques des camions en Ontario, mieme ceux qui n'etaient pas renforcees. Mots-cles: trous d'homme en beton prefabrique, essai a pleine echelle, environnement d'essai contri)lee, norme de charges de camions de l Ontario, interaction sol-structure., 1. Introduction A manhole is a hole through which a person can gain access to an underground structure such as storm water or sewer systems. Precast concrete manholes are among [...]

Glyben is an artificial soil comprising bentonite mixed with glycerin that has been used recently in scaled model tests to study seismic soil structure interaction. In spite of recent interest in glyben, factors affecting the dynamic properties of this material have not been well established. This paper presents the results of vane shear tests, cyclic triaxial tests, resonant column tests and bender element tests undertaken to characterize the dynamic properties of glyben. The results show that the modulus ratio of glyben decreases with increasing shear strain amplitude similar to that observed for natural clays. However, there are significant thixotropic changes in the properties of glyben after mixing bentonite with glycerin. In addition, glyben exhibits time-dependent volumetric compression after the application of isotropic consolidation pressure, the damping ratio of glyben is higher than that of natural clays and the dynamic properties of glyben are strongly influenced by temperature. These factors should be considered when interpreting the results of scaled physical model tests using glyben. DOI: 10.1061/(ASCE) 1090-0241 (2009) 135:2(280) CE Database subject headings: Geotechnical models; Soil dynamics; Clays; Damping; Shear; Thermal factors; Cyclic tests.

Abstract: The precast concrete pipe industry is in continuous pursuit to add value to its products to strengthen its market competitiveness against other pipe products. The research reported in this [...]

Abstract: Concrete pipes represent the backbone of the municipal storm and wastewater collection systems of Ontario, Canada. Industry and academia partnered on a research effort that aimed at developing new [...]

Abstract: The helical pile is a foundation system that is used to support new residential and commercial buildings and to stabilize repairs of existing structures. It represents an attractive option [...]