Applied Mathematics and Mechanics (English Edition) ›› 2014, Vol. 35 ›› Issue (9): 1129-1154.doi: https://doi.org/10.1007/s10483-014-1859-6

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Implicit scheme for integrating constitutive model of unsaturated soils with coupling hydraulic and mechanical behavior

Tian-tian MA1, Chang-fu WEI1,2, Pan CHEN1, Hou-zhen WEI1   

  1. 1. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan 430071, P. R. China;
    2. College of Civil and Architectural Engineering, Guilin University of Technology, Guilin 541004, Guangxi Province, P. R. China
  • Received:2013-09-24 Revised:2014-01-16 Online:2014-09-01 Published:2014-09-01
  • Supported by:
    Project supported by the National Natural Science Foundation of China (No. 11072255) and the Natural Science Foundation of Guangxi Province (No. 2011GXNSFE018004)

Abstract: A constitutive model of unsaturated soils with coupling capillary hysteresis and skeleton deformation is developed and implemented in a fully coupled transient hydro-mechanical finite-element model (computer code U-DYSAC2). The obtained results are compared with experimental results, showing that the proposed constitutive model can simulate the main mechanical and hydraulic behavior of unsaturated soils in a unified framework. The non-linearity of the soil-water characteristic relation is treated in a similar way of elastoplasticity. Two constitutive relations are integrated by an implicit return-mapping scheme similar to that developed for saturated soils. A consistent tangential modulus is derived to preserve the asymptotic rate of the quadratic convergence of Newton's iteration. Combined with the integration of the constitutive model, a complete finite-element formulation of coupling hydro-mechanical problems for unsaturated soils is presented. A number of practical problems with different given initial and boundary conditions are analyzed to illustrate the performance and capabilities of the finite-element model.

Key words: unsaturated soil, capillary hysteresis, elastoplastic coupling constitutive model, stress integration, finite-element method

2010 MSC Number: 

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