Prediction of Embankment Settlement Over Soft Soils: Fid-Bau Portal

Prediction of Embankment Settlement Over Soft Soils

C. Vipulanandan / O. Bilgin / Y. J. A. Guezo / K. Vembu / M. B. Erten

The objective of this project was to review and verify the current design procedures used by TxDOT to estimate the total and rate of consolidation settlement in embankments constructed on soft soils. Methods to improve the settlement predictions were identified and verified by monitoring the settlements in two highway embankments over a period of 20 months. Over 40 consolidation tests were performed to quantify the parameters that influenced the consolidation properties of the soft clay soils. Since there is a hysteresis loop during the unloading and reloading of the soft CH clays during the consolidation test, three recompression indices (Cr1, Cr2, Cr3) have been identified with a recommendation to use the recompression index Cr1 (based on stress level) to determine the settlement up to the preconsolidation pressure. Based on the laboratory tests and analyses of the results, the consolidation parameters for soft soils were all stress dependent. Hence, when selecting representative parameters for determining the total and rate of settlement, expected stress increases in the ground should be considered. Also the 1-D consolidation theory predicted continuous consolidation settlement in both of the embankments investigated. The predicted consolidation settlements were comparable to the consolidation settlement measured in the field. Constant Rate of Strain test can be used to determine the consolidation parameters of the soft clay soils. The effect of Active Zone must be considered in designing the edges of the embankments and the retaining walls.