Abstract: With the development of the national strategy for the Greater Bay Area,deep foundation pits have been widely applied.It is necessary to study the deformation law of deep foundation pits in the deep soft soil layers of the Greater Bay Area to provide reference for design and construction.Based on the 40 m deep foundation pit project in the China Greater Bay Area,the deformation characteristics of the diaphragm wall during the excavation process are investigated comprehensively.During the excavation stage,the deformation rate of the wall caused by the excavation of the marine soft soil layer is 2～6 mm/d,increasing with the excavation depth; the maximum deformation occurs below the excavation surface.At the end of excavation,the maximum lateral displacement of the wall is mainly between 0.1% and 0.5% H_e. The deformation data of the wall indicates that excavation of the marine soft soil layer is the main cause of wall deformation,which needs to be taken seriously in the design and construction stages to ensure the safety of the deep foundation pit itself.

Key words: marine soft soil, 40 m class deep foundation pit, diaphragm wall, deformation performance