ABSTRACT
The heave of the bottom of excavation has long being paid attention to since 1950s. Stanley (1956) reported that large heave of bottom of excavation can occur for deep excavation without dewatering, however, the heave of excavation bottom can be greatly reduced by dewatering before excavation commence. Burland (1979) has investigated soil movements around excavations in London clay. Buford (1988) reported the heave of tunnels beneath an excavation in London due to the heave of overlying soil. The maximum heave measured was about 20-30 mm after excavation activities in 1957 and this upward displacement still continued and maximum magnitude reached about 50 mm in 1986. Lo & Ramsay (1991) proposed the methodology to deal with the “construction over tunnels” problem by a case record of excavation above subway tunnels in Toronto. Zheng et al. (2010) carried centrifuge tests to investigate the effect of overlying on tunnel linings.
