Peak strength characteristics and failure envelope model of unsaturated soils

XU Xiao; CAI Guo-qing; LI Jian; ZHAO Chen-gang; ZHAO Chun-lei

doi:10.11779/CJGE202007004

Volume 42 Issue 7

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Chinese Journal of Geotechnical Engineering > 2020 > 42(7): 1211-1219. > DOI: 10.11779/CJGE202007004

XU Xiao, CAI Guo-qing, LI Jian, ZHAO Chen-gang, ZHAO Chun-lei. Peak strength characteristics and failure envelope model of unsaturated soils[J]. Chinese Journal of Geotechnical Engineering, 2020, 42(7): 1211-1219. DOI: 10.11779/CJGE202007004

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Peak strength characteristics and failure envelope model of unsaturated soils

XU Xiao^{1, 2,},
CAI Guo-qing^2, ,,
LI Jian²,
ZHAO Chen-gang^{2, 3},
ZHAO Chun-lei⁴

1.
Bridge and Tunnel Research Center, Research Institute of Highway, Ministry of Transport, Beijing 100088, China
2.
Key Laboratory of Urban Underground Engineering of Ministry of Education, Beijing Jiaotong University, Beijing 100044, China
3.
School of Civil Engineering, Guilin University of Technology, Guilin 541004, China
4.
City Construction Department, Beijing City University, Beijing 100086, China

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Received Date: September 29, 2018
Available Online: December 05, 2022

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Abstract

Abstract

The peak strengths and failure envelopes of unsaturated compacted soils are investigated via triaxial compression and uniaxial tensile tests over a wide range of water content. Based on the experimental evidence, a method for deriving failure envelope model for unsaturated soils is discussed. Firstly, according to the mode of failure, the failure envelope can be approximated by a bilinear Mohr–Coulomb envelope. Secondly, the effect of unsaturated state on the peak strength can be described in terms of dilatancy and interparticle stress. Then accounting for the primary components of unsaturated peak strength and its description, two curved failure envelopes with clear physical meaning are proposed, named after cohesion-dilatancy and interparticle stress-dilatancy envelope respectively. Based on the piecewise linear failure envelope, the method for determining the parameters of the curved failure envelope is discussed. Finally, the failure envelopes and their variation characteristics under different water contents in unsaturated state are given and analyzed.
- unsaturated soil,
- crack failure,
- shear failure,
- failure envelope,
- dilatancy,
- interparticle stress

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References

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