Abstract: The characteristics of soils under long-term repeated surcharge loads are discussed in detail by studying the relevant results reported in the references. The concept of introducing critical repeated stress level into the Carter Model is expounded based on the critical state soil mechanics; and the Carter Model is modified. The modified Carter Model can reflect reasonably the main characteristics of soils under long-term repeated surcharge loads. Then, the soil and pile foundation interaction under long-term repeated loading is analyzed in detail using the plane strain FEM program. In the program, the characteristics of soils under long-term repeated surcharge loads are simulated by the modified Carter Model. The law of settlements and displacements of soils and piles under long-term repeated loading is discussed; then the influences of several factors such as the magnitude of θ, critical repeated stress level and pile stiffness, etc., are discussed. Finally, some useful conclusions are drawn.

Key words: long-term repeated loading, critical state soil mechanics, passive pile, interaction, FEM