| Popis: |
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. |
