Abstract: The proposed widened embankment for the flood storage and detention area construction project is over the soft soils. After years of consolidation, the soft soil properties under the existing embankment are different from the soft soil parameters outside the embankment influence zone. The proposed embankment body is formed by adding fill soils to the existing embankment. Firstly, the hazard characteristics of the existing embankment for the proposed reinforcement project were analyzed. Then, based on laboratory and in-situ testing methods, a series of soft soil tests were performed to determine the soft soil parameters inside and outside the existing embankment, and the recommended values of the stability optimization design parameters for the proposed embankment were determined. Finally, a new parameter determining and estimation method of the soft soil for existing embankment in the flood storage and detention areas was proposed based on the similar engineering embankment soft soil parameters. The evaluation results can provide some guidance for obtaining the parameters of the proposed embankment soft soil formed by the addition of exisitng embankment and for the design of proposed embankment.

Key words: Soft Soils, Drainage Consolidation, Foundation Treatment, Insitu test, Flood Storage and Detention Area