Abstract：The scale of Kaihuacheng deep foundation pit in Guangzhou is quite large，with depth of 10.7～12.3 m. The strata of the pit field mainly consist of plastic alluvial silty clay，plastic～stiff plastic residual silty clay，and medium compact residual silt. The neighbouring environment is complicated. The support design practice of the pit using soil nailing is presented in this paper. Some affecting factors are considered and measures adopted in order to control the displacement of the pit. Nails are arranged with alternation of long and short lengths. Prestressed bolts are installed on upper part of the pit slope in some deeper and steeper segments. Certain slope angle，1∶0.6 or 1∶0.2，is adopted in some segments according to the condition of the field. Minitype steel pipe piles are installed for advance support in vertical digging segment. The characteristics of pit displacement and the reason why big horizontal displacement occurs are analysed. The support result of the pit is also evaluated.
