Rock and Soil Mechanics ›› 2020, Vol. 41 ›› Issue (8): 2665-2674.doi: 10.16285/j.rsm.2019.6580

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Calculation of mean intergranular stress and its application in unsaturated soil

SONG Zhao-yang1, ZHAO Cheng-gang1, WEI Chang-fu2, MA Tian-tian2   

  1. 1. School of Civil Engineering, Beijing Jiaotong University, Beijing 100044, China 2. State Key Laboratory of Geomechanics and Geotechnical Engineering, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences, Wuhan, Hubei 430071, China
  • Online:2020-08-09 Published:2021-01-22
  • Contact: ZHAO Cheng-gang, male, born in 1955, PhD, Professor, mainly engaged in research on rational soil mechanics, unsaturated soil mechanics and geotechnical earthquake engineering. E-mail:
  • About author:SONG Zhao-yang, male, born in 1993, PhD candidate, mainly engaged in research on unsaturated soil mechanics.
  • Supported by:
    the Fundamental Research Funds for the Central Universities (2019YJS137).

Abstract: The physicochemical interactions between different phases of the soil have an important impact on the geotechnical engineering related to environment and energy. The principle of effective stress is always the most important and effective theory to solve the relevant problems. However, the change of inter-particle stress caused by physicochemical effects cannot be accurately described by current effective stress equation. In response to the above problems, a mean intergranular stress expression that uniformly describe capillary, adsorption and osmosis effects between soil particles has recently been proposed. The purpose of this research is to realize the quantitative calculation of the mean intergranular stress and verify its stability and effectiveness. Firstly, the physical meaning of each part in the expression of mean intergranular stress is analyzed. Through analyzing the parameter in the expression, the variation rule of each part of mean intergranular stress with the water content and the concentration of pore water are obtained. Then, the formula characterizing the solid-liquid interface interaction for the surface force potential is derived, which can be used for the quantitative calculation of the mean intergranular stress equation. Finally, the mean intergranular stress of unsaturated soil in the critical state is calculated, and applied to simulate the coupled chemical-mechanical loading test of unsaturated soil. The calculated results show that there is a unique relationship between mean intergranular stress and shear strength in the critical state, and the chemical-mechanical calculation results give good agreement with the experimental results, verifying the stability and effectiveness of the mean intergranular stress.

Key words: unsaturated soil, physicochemical effect, mean intergranular stress, surface force potential