A new simplified method for calculating consolidation settlement of multi-layer soft soils with creep under multi-stage ramp loading

Abstract

In normal practice, a multi-stage surcharge loading is applied gradually to achieve a certain strength of soft soils, and thus it is important to study the settlement of soft soils under multi-stage ramp loading. In this study, a new simplified method is developed to calculate the settlement of multi-layer soft soils exhibiting creep subjected to the multi-stage loading under a one-dimensional straining condition. The Zhu and Yin method is utilized to obtain the average degree of consolidation for multi-layer soils under each loading stage. The effects of creep compression on excess pore water pressure and total settlement during consolidation stage are elaborated. Subsequently, two typical projects, Skå-Edeby with 46 years’ recorded settlement data and highway embankment in the Berthierville area, are selected as the typical multi-layer soil profiles. Cases with three different loadings and two different over consolidation ratio (OCR) values are analyzed using the finite element modeling, namely the new simplified method, and the Hypothesis A method. With the use of the results from finite element analysis as the reference, the new simplified method offers a good estimation of the settlement for all the cases and outperforms the Hypothesis A method in terms of accuracy.