Citation

Legget RF, Peckover FL. Can. Geotech. J. 1973; 10(3): 504-519.

Copyright

(Copyright © 1973, National Research Council of Canada)

DOI

10.1139/t73-041

PMID

unavailable

Abstract

The Miramichi bridges in New Brunswick, each of six 200-ft (61-m) spans, were built as part of the Intercolonial Railway by Sir Sandford Fleming in 1871-75. When construction of the Northwest Bridge started, it was found that early borings were incorrect and the layer of gravel and sand on which the piers were to rest was underlain by deposits of silty sand and clay-silt. The caissons of the piers were therefore enlarged in order to spread the load better. On observing settlements during construction, Fleming stopped the work and preloaded each pier in excess of the design load. He resumed construction when he observed that settlements had stopped.The level of the bridge piers has been measured periodically since 1914. Recent borings have been made, giving a basis for analysis of the bridge performance. Calculated primary settlements are compared with those measured during construction. Surveyed pier movements are adjusted to reduce errors, and compared with calculated secondary settlements. It is deduced that the piers have settled at a rate equal to or less than that indicated by the theory of secondary compression.The bridge is continuing to perform in a predictable and safe manner, providing an outstanding example of early Canadian engineering.


Les ponts de la Miramichi au Nouveau Brunswick, chacun de six travées de 200 pi., ont été construits en 1871-75 par Sir Sandford Fleming, faisant partie du Chemin de fer Intercolonial. Au début des travaux de construction du pont nord-ouest, on a découvert que les forages préliminaires étaient inexacts et qu'en realité des dépôts de sable silteux et d'argile-silt se trouvaient au dessous de la couche de gravier et de sable sur laquelle devait reposer les piliers. Pour compenser, les caissons de fondation des piliers furent élargis afin de répartir d'avantage la charge. Observant des tassements, Fleming devait suspendre les travaux et appliquer une surcharge dépassant la charge de calcul sur chaque pilier. Les travaux devaient reprendre lorsqu'on observa l'état stable des piliers.Le niveau des piliers du pont a été mesuré périodiquement depuis 1914. Des forages ont été effectués récemment permettant ainsi d'analyser la performance du pont. Les tassements primaires calculés sont comparés à ceux mesurés dura...

Language: en