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A study of the weathering of the Bukit Timah granite Part B: Field and laboratory investigations

  • J. Zhao
  • B. B. Broms
  • Y. Zhou
  • V. Choa
Article

Abstract

Field investigations consisting of surface seismic refraction and electrical resistivity surveys, drilling and downhole geophysical logging of the rock mass and of the residual soil indicate that the weathering of the Bukit Timah granite has been rapid and is primarily caused by chemical decomposition due to the tropical climate in Singapore. The granite is usually overlain by a thick layer of residual soil. Laboratory tests indicated a large reductions of the material strength, the modulus of elasticity, the rock mass quality and other mechanical properties of the weathered granite. Apart from the mechanical properties of the residual material and/or of the weathered granite rock, physical properties including density, water content, Atterberg's limits, grain size distribution, permeability, sonic velocity and electrical resistivity were also studied in order to assess the weathering grade and the weathering processes.

Keywords

Rock Mass Weathering Uniaxial Compressive Strength Seismic Velocity Plasticity Index 

Étude de l'altération du granite de Bukit Timah (Singapour) 2e partie: Études sur le terrain et en laboratoire

Résumé

Les études de terrain ont comporté des mesures géophysiques (sismiques, réfraction superficielle et résistivité électrique), ainsi que des forages et des enregistrements, de diagraphie dans la masse rocheuse et dans le sol résiduel. Elles ont montré que l'altération du granite de Bukit Timah a été rapide et causée principalement par une décomposition chimique due au climat tropical de Singapour. Le granite est en général recouvert d'une couche épaisse de sol résiduel. Les essais de laboratoire ont montré une importante diminution de la résistance du module d'élasticité, de la qualité du massif rocheux et des autres caractéristiques mécaniques du granite altéré. En dehors des caractéristique mécaniques du sol résiduel et/ou du granite altéré, les propriétés physiques ont également été étudiées, incluant la densité, la teneur en eau, les limites d'Atterberg, l'analyse granulométrique, la perméabilité, la vitesse du son et la résistivité électrique, qui ont permis de définir des processus et des degrés d'altération.

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Copyright information

© International Association of Engineering Geology 1994

Authors and Affiliations

  • J. Zhao
    • 1
  • B. B. Broms
    • 1
  • Y. Zhou
    • 1
  • V. Choa
    • 1
  1. 1.School of Civil & Structural EngineeringNanyang Technological UniversitySingapore

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