Site investigations for Canada's first underground railway

About 1000 yards of the Toronto underground railway was founded on or in Dundas shale; the remainder was founded above rock in soil varying from hard glacial till to water deposited soils including clays, silts and uniform water- bearing sands. Test borings were undertaken to obtain undisturbed samples and to permit installation of piezometers. Some 37 holes, giving a total footage of 1459 ft, were put down in the summer of 1944. Borings were extended 10 ft. into rock to positively establish bed rock. The cut-and-cover method of construction was an imperative because the railway was designed to be as shallow as possible to interact easily with surface transportation. Normal traffic, including tram cars, was carried on a temporary deck while railway construction proceeded underneath. Support of the sides was achieved with driven soldier piles at 6-8 ft intervals along both sides of the excavation. A reinforced concrete box structure was constructed to replace temporary wooden board shoring and finally backfilled with sand. The street was repaved after removal of the deck. No major soil or foundation problems developed during construction and several unusual and difficult underpinning projects were carried out. All soil samples are stored at the Royal Ontario Museum. Other projects included a study of strains on the temporary steel deck, noise problem studies on the completed underground and a study of the vibrations during pile driving.Environ 1000 verges du m\ue9tro de Toronto reposent sur les schistes de Dundas ou traversent ce genre de formation; le reste de la ligne est \ue9tabli au-dessus du roc dans des sols variant d'argiles \ue0 blocaux dures \ue0 des sols d\ue9pos\ue9s comprenant des argiles, des silts et des sables aquif\ue8res. Aucun probl\ue8me important de sol ou de fondation ne s'est pr\ue9 sent\ue9 durant les travaux, et plusieurs travaux de sout\ue8 nement \ue0 la fois inhabituels et complexes ont \ue9t\ue9 r\ue9alis\ue9s. L'ensemble des \ue9chantillons pr\ue9lev\ue9s se trouve au Royal Ontario Museum. On a \ue9galement proc\ue9d\ue9 \ue0 d'autres travaux comprenant une \ue9tude des contraintes sur la plate-forme m\ue9 tallique provisoire, une \ue9tude des niveaux de bruit dans le m\ue9tro parachev\ue9 et une \ue9tude des vibrations durant le battage des pieux.Peer reviewed: NoNRC publication: Ye