By studying the marine soft clay 9~18 m below the land surface, on which many underground projects are laid in the Binhai New Area, Tianjin, the consolidated-undrained triaxial compression test (CU), unconsolidated-undrained triaxial compression test (UU) and simulated pressure path tests (DEP) of excavation are carried out on the stress and strain controlled triaxial shear penetration apparatus. The results show that the behaviors of soft soil under different stress paths are related to initial consolidation states. It is safe to use the soil shear strength properties of CU test in the design of foundation pit bracing of the Binhai New Area.