Abstract: The tidal flats in coastal areas provide large area of land for the engineering construction and socioeconomic development. But the soft soils in the tidal flats are deep and widely distributed, which is easy to cause hazards such as the excessive settlement of the storage yards, the differential settlement and global stability issues for the foundations during the construction and the operations. A nuclear power plant in the eastern coastal area is presented in this paper as an example. The subsurface conditions, such as, engineering geology, the main physical and mechanical properties of the soft soils are evaluated by means of the geological exploration results combined with the subsurface investigations in proposed temporary storage yard. It is proposed that the design concept of “multi-stage gentle slope surcharging and geosynthetic reinforcement” is adopted. Through the global stability analysis and the numerical simulations, the results indicate that the stability of the graded construction over the deep soft soils and the safety of the influence on the surrounding buildings are effectively ensured by measures such as geosynthetic reinforcement and the different zoned construction. The feasibility of the design concepts are verified.

Key words: Pre-Loading, Edge Effect, Settlement, Soft Soils