Application of Multiple Support Forms in Foundation Pit Support in Soft Soil

In order to design a safe and economical foundation pit support scheme for a deep foundation pit project in soft soil in Nansha District, Guangzhou, the Lizheng Deep Foundation Pit 7.0 software was taken to conduct unit calculation for each support section and excavation condition of the pit, and the monitoring data during the construction process was compared.The calculation results indicate that for one story basement foundation pit with a small span in this project, when the surrounding space is limit, the maximum horizontal displacement of the pit could be controlled within 40mm if the support scheme was taken where enclosure piles are combined with internal support and pit reinforcement, and that different kinds of enclosure piles could be combined to meet the pit deformation requirements.Gravity cement soil wall combined with internal support is adopt to "Pit-in-Pit" where the pit is deepen, and the maximum horizontal displacement can be controlled within 20mm.The monitoring data shows that after adopting multiple support forms, the maximum horizontal and vertical displacement at the top of the enclosure piles is respectively 28.7mm and 17.7mm, and that the maximum horizontal displacement of the deep soil layer is around 13.9mm, and that the maximum subsidence of adjacent buildings is around 11.4mm, all of which stay within specification range.Theoretical calculation and monitoring data show that the pit is in a safe state, thus achieving benefits.