Abstract: Based on settlement and cracking problems of existing buildings at Hexi district in Nanjing, a reinforcement technology of super-long steel tube static pile is put forward. In order to improve building safety, two lines of defense made by static piles and reserve piles were further proposed for reinforcement measures, and static pressure piles as the two lines of defense were applied in batches during construction. By monitoring the settlement deformation of the building before and after reinforcement, it is found that the reinforcement building is less affected by adjacent foundation pit construction. Especially, the influence of a foundation pit construction at a distance of nearly 12 m away is much less than that of a foundation pit construction at a distance of 220 m far away. It shows that the reinforcement method reduces effectively appearing disasters of further settlement and cracking of the existing buildings. Thus, the validity and rationality of applying super-long steel pipe static piles in the low floodplain area of the Yangtze River to improve the ability of buildings to resist deformation, has been verified indeed.

Key words: Yangtze low floodplain area, deep foundation pit, super-long steel pipe pile, monitor, reinforcement method