Test study and constitutive modelling of the time-dependent stress-strain behavior of soils

Jianhua Yin, F. Tong

Research output: Chapter in book / Conference proceedingConference article published in proceeding or bookAcademic researchpeer-review

2 Citations (Scopus)

Abstract

This paper reports firstly the experimental data from one-dimensional (1D) straining oedometer tests and 2D consolidated undrained compression (CU) tests on a bentonite (clay mineral montmorillonite) mixed with different percentages of silicon sand. The 1D tests include (i) multi-staged loading tests with unloading/reloading and with creep and swelling and (ii) step-changed constant rate of strain compression tests with unloading/reloading in 1D straining as well. From the test data, creep, swelling and strain rate effects are observed and discussed. This paper introduces a new 1D Elastic Visco-Plastic model considering both creep and swelling (called 1D EVPS) for soils in 1D straining based on the previous 1D Elastic Visco-Plastic (1D EVP) models. The 1D EVPS model is used to simulate a step-changed changed constant rate of strain compression test with unloading/reloading in 1D straining with comparison with measured data. In addition, the 1D EVPS model is used to simulate single-staged constant rate of strain CU tests and relaxation tests. The typical results from a selected 2D CU test on a bentonite mixed 70% silicon sand under effective cell pressure of 100 kPa in a triaxial state compressed with step-changed constant rate of strain and unloading-reloading are presented and discussed in the paper. The 2D CU test data show clearly strain rate effects and unloading-reloading loops. The main conclusions from the study are: (a) the stress-strain behaviour of a bentonite mixed with different percentages of silicon sand exhibits strong dependence on time and strain rate; (b) in 1D straining condition, there exists a creep region when stress-strain state closer to the normal consolidation line (NCL) and a swelling region when far away from the NCL; (c) the 1D EVPS model can re-produce well the time-dependent stress-strain behaviour of the soil including creep, swelling, strain effects, relaxation, and unloading-reloading loops in 1D straining condition; and (d) the data from 2D consolidated undrained triaxial compression tests on the bentonite-sand mixture also show the strong strain effects and unloading-reloading loops.
Original languageEnglish
Title of host publication18th International Conference on Soil Mechanics and Geotechnical Engineering: Challenges and Innovations in Geotechnics, ICSMGE 2013
PublisherIOS Press
Pages283-286
Number of pages4
Publication statusPublished - 1 Jan 2013
Event18th International Conference on Soil Mechanics and Geotechnical Engineering, ICSMGE 2013 - Paris Convention Centre, Paris, France
Duration: 2 Sep 20136 Sep 2013

Conference

Conference18th International Conference on Soil Mechanics and Geotechnical Engineering, ICSMGE 2013
Country/TerritoryFrance
CityParis
Period2/09/136/09/13

Keywords

  • Creep
  • Relaxation
  • Strain-rate
  • Stress-strain
  • Swelling
  • Time-dependent
  • Visco-plastic

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology

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