Mechanism of settlement of ramp loading roadbed on soft ground is analyzed; and proof of settlement-time curve appearing S-shape is conducted directly based on consolidation degree of one-dimension soil consolidation theory. Mathematical analyses of Gompertz
logistic
Weibull growth model that appearing S-shape are conducted. Although Gompertz
logistic growth models are adopted extensively to predict settlement of ramp loading roadbed
they have deficiencies such as: (1)neglecting loading velocity; (2)neglecting construction art; (3) relative constant ratio of settlement at inflection point to ultimate settlement. Good usability of Weibull growth model is pointed out. Finally
suggests on prediction of soft roadbed settlement are proposed.