Comparing Non-Displacement and Displacement Piles using In-sit Load Tests

Fazli R. Shah

In the proceedings of: GeoVancouver 2016: 69th Canadian Geotechnical Conference

Session: FOUNDATION DESIGN - IV Soil-Structure Interaction

ABSTRACT: There has been consensus on the enhanced geotechnical capacity of displacement piles as compared to non-displacement piles due the soil improvement effect of the former pile type by virtue of radial displacement along the shaft and pre-loading at the tip of the pile. Many researchers have developed different models over time to estimate the enhancement of geotechnical capacity of partial and full displacement piles. The results of such research have always been reported in terms of revised values for the empirical coefficients used in already existing pile design methods. However, there is a basic lack of evidence in comparison of geotechnical capacities of displacement and non-displacement piles as both types are seldom used on same project and at best the comparison has been made for similar soil conditions in the nearby areas or projects. The objective of present research is thus to compare the geotechnical capacities of various pile types in same soils. Four axial compression load tests were conducted on heavily instrumented piles, one each of drilled cast-in-place (CIP), continuous flight auger (CFA), drill displacement steel pile (DDSP) and drilled displacement (DD) type of same length and similar dimensions installed at one cohesive site in Alberta to eliminate the soil differing and scale effects. The paper evaluates the axial capacities and the load-transfer mechanisms of all four types of piles during axial load tests to assess the increase in geotechnical capacity of the displacement piles in comparison with non-displacement pile and evaluates the existing design methods adopted for these types of piles.

RÉSUMÉ: Il existe un consensus sur la capacité géotechnique renforcée des piles de déplacement par rapport aux Piles de non-déplacement-chargement à la base du pieu. Plusieurs chercheurs ont développé différents modèles pour estimer le renforcement de la capacité géotechnique des pieux partiellement et complétement enfoncés. Les résultats de ce type de recherches ont été présentés en termes de valeurs empiriques révisées pour les méthodes déjà existantes de conception de piles. Cependant, piles de déplacement et non enfoncés comme tous les deux sont rarement utilisés dans le même projet et les meilleures comparaisons ont été comparer les capacités géotechniques de différents types de piles de mêmes sols. Quatre essais de charge de compression axiale ont été réalisées sur pilotis fortement instrumentés, un chacun percé coulé en place (CIP), tarière continue (CFA), forage pieux d'acier de déplacement (DDSP) et forés déplacement (DD) type de même longueur et dimensions similaires installées sur un site cohérent en Alberta pour éliminer les sols différents et effets d'échelle. Cet article scientifique mesure les capacités axiales et les mécanismes de transfert de charge des quatre types de pieux lors des essais de chargement axial, ailleurs, on fait aussi une comparaison entre les méthodes de conception existantes, adoptées pour ces types de piles. 1 INTRODUCTION There has been continuous research to enhance the knowledge and understanding of factors governing the axial capacities of piles. In general, axial capacities depend upon soil type, pile type, pile surface roughness, and method of installation and so on. Displacement or densification effects of pile installation can significantly affect the pile capacities and thus classify piles into non-displacement, partial displacement, and full displacement piles. Examples of non-displacement piles are drilled cast-in-place or bored pile that is constructed by drilling an open shaft and pouring the concrete into it upon completion. The stabilization of open pile shaft

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Cite this article:
Fazli R. Shah (2016) Comparing Non-Displacement and Displacement Piles using In-sit Load Tests in GEO2016. Ottawa, Ontario: Canadian Geotechnical Society.

@article{3760_0722123148,author = Fazli R. Shah,title = Comparing Non-Displacement and Displacement Piles using In-sit Load Tests,year = 2016}