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 language | English |
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Title of host publication | 18th International Conference on Soil Mechanics and Geotechnical Engineering: Challenges and Innovations in Geotechnics, ICSMGE 2013 |
Publisher | IOS Press |
Pages | 283-286 |
Number of pages | 4 |
Publication status | Published - 1 Jan 2013 |
Event | 18th International Conference on Soil Mechanics and Geotechnical Engineering, ICSMGE 2013 - Paris Convention Centre, Paris, France Duration: 2 Sept 2013 → 6 Sept 2013 |
Conference
Conference | 18th International Conference on Soil Mechanics and Geotechnical Engineering, ICSMGE 2013 |
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Country/Territory | France |
City | Paris |
Period | 2/09/13 → 6/09/13 |
Keywords
- Creep
- Relaxation
- Strain-rate
- Stress-strain
- Swelling
- Time-dependent
- Visco-plastic
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology