A New Simplified Hypothesis B Method and Its Verification for Calculating Consolidation Settlements of Single and Multi-layered Clayey Soils Exhibiting Creep

Jian Hua Yin, Wei Qiang Feng

Research output: Unpublished conference presentation (presented paper, abstract, poster)Conference presentation (not published in journal/proceeding/book)Academic researchpeer-review

Abstract

The calculation of the consolidation settlement of clayey soils with creep behaviour has been a challenging issue with a long history. After discussion of the assumptions and features of methods based on Hypothesis A and Hypothesis B, the authors present a new simplified Hypothesis B method for calculation of consolidation settlement of a single layer of a clayey soil with creep. Equations of this method are derived based on the “equivalent time” concept for different stress-strain states. This simplified Hypothesis B method is then used to calculate the consolidation settlement of a number of typical consolidation problems. The approximation and verification of this simplified method are examined by comparing the calculated settlements with settlements computed using two fully coupled finite element consolidation analysis programs using elastic visco-plastic constitutive models (Hypothesis B) and the Hypothesis A method. It is found that the curves calculated using the new Hypothesis B simplified method with a factor α= 0.8 are close to curves from two Finite Element (FE) model simulations with relative errors in the range of 0.37% ~ 8.42% only for three cases with three different thicknesses of Hong Kong Marine Clay (HKMC). In overall, the settlements calculated using Hypothesis A method are smaller than those from the two FE simulations with relative error in the range of 6.52% ~ 46.17% for the three layers of HKMC. In addition, this new simplified Hypothesis B method is used to calculate the average strain of consolidation tests. The calculated results are compared with the test data, and values from a fully coupled finite difference consolidation analysis using Yin and Graham’s elastic visco-plastic constitutive model (Hypothesis B), and Hypothesis A method. It is found that, again, the results from the new simplified Hypothesis B method are very close the measured data. In conclusion, the new simplified Hypothesis B method is a suitable simple method, by spread-sheet calculation of the consolidation settlement of a single layer of a clayey soil with creep. This new method has been extended to multi-layered soils and corresponding equations are presented. Consolidation settlements of four cases of two-layered soils are calculated using this new method, Hypothesis A method, and the fully coupled FE simulations. Results are compared and discussed. It is found again that the results from the new simplified Hypothesis B method are very close to the results from the FE simulation and have least relative errors. It is concluded that the proposed new simplified Hypothesis B method is easy to use and has a good accuracy for calculating settlements.

Original languageEnglish
Pages1452-1463
Number of pages12
Publication statusPublished - 1 Jan 2017
Event15th International Conference of the International Association for Computer Methods and Advances in Geomechanics, IACMAG 2017 - Wuhan, China
Duration: 19 Oct 201723 Oct 2017

Conference

Conference15th International Conference of the International Association for Computer Methods and Advances in Geomechanics, IACMAG 2017
CountryChina
CityWuhan
Period19/10/1723/10/17

Keywords

  • Clayey soils
  • Consolidation
  • Creep
  • Settlement
  • Time-dependent
  • Visco-plastic

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Applied Mathematics

Cite this