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Engineering geological investigations for pile foundations on a deeply weathered granitic rock in Hong Kong

  • Irfan T. Y. 
  • Powell G. E. 
Article

Summary

In weathered rocks the determination of founding depth for the foundations of major structures is complicated by the highly variable nature of the material. In order to ensure that the properties of the soil or rock mass on which the structure is to be founded correspond to those assumed in design it is necessary to unambiguously characterise the mass.

This paper outlines a scheme used to characterise the weathered rock mass and describes the engineering geological logging of the large diameter pile foundations on a deeply weathered granodiorite for a series of bridges in the New Territories, Hong Kong. The results of field and laboratory index and engineering tests carried out to determine the characteristics of the foundation rock are discussed. The drawbacks of use of RQD, percentage core recovery or probing tests as a means of determining and proving founding depth of piles are also discussed.

Keywords

Rock Mass Uniaxial Compressive Strength Rock Material Engineer Geology Pile Foundation 

Études géologiques pour fondations par pieux dans un granite profondément altéré à Hong Kong

Résumé

La nature très variable des roches altérées rend compliquée la détermination de la profondeur de l'assise des fondations pour les structures importantes. Il devient nécessaire de définir clairement la couche de fondation, afin d'assurer que les caractéristiques des sols ou roches correspondent bien à celles préconisées au moment de l'étude.

Ce rapport donne un aperçu sur une méthode de caractérisation d'une masse rocheuse altérée et décrit l'enregistrement des paramètres géologiques lors de l'exécution de pieux de grand diamètre dans une granodiorite profondément altérée, pour une série de ponts dans les Nouveaux Territoires de Hong Kong. On examine les résultats d'essais de classification et d'essais mécaniques, exécutés sur place et en laboratoire, pour définir les caractéristiques des roches de fondation. On examine aussi les désavantages liés à l'utilisation du RQD, du pourcentage de récupération et des essais de perforation pour la reconnaissance et le contrôle de l'assise des pieux.

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Copyright information

© International Assocaition of Engineering Geology 1985

Authors and Affiliations

  • Irfan T. Y. 
    • 1
  • Powell G. E. 
    • 1
  1. 1.Engineering Development Dept. Geological Control Office 6th Floor-Empire CentreKowloonHong Kong

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