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Geomechanics and Engineering
  Volume 11, Number 6, December 2016 , pages 739-756
DOI: https://doi.org/10.12989/gae.2016.11.6.739
 


A modified shear strength reduction finite element method for soil slope under wetting-drying cycles
Yiliang Tu, Zuliang Zhong, Weikun Luo, Xinrong Liu and Sui Wang

 
Abstract
    The shear strength reduction finite element method (SSRFEM) is a powerful tool for slope stability analysis. The factor of safety (FOS) of the slope can be easily calculated only through reducing effective cohesion (c') and tangent of effective friction angle (tanφ') in equal proportion. However, this method may not be applicable to soil slope under wetting-drying cycles (WDCs), because the influence of WDCs on c' and tanφ' may be different. To research the method of estimating FOS of soil slopes under WDCs, this paper presents an experimental study firstly to investigate the effects of WDCs on the parameters of shear strength and stiffness. Twelve silty clay samples were subjected to different number of WDCs and then tested with triaxial test equipment. The test results show that WDCs have a degradation effect on shear strength (σ1σ3)f, secant modulus of elasticity (Es) and c' while little influence on φ'. Hence, conventional SSRFEM which reduces c' and tanφ' equal proportion cannot be adopted to compute the FOS of slope under conditions of WDCs. The SSRFEM should be modified. In detail, c' is merely reduced among shear strength parameters, and elasticity modulus is reduced correspondingly. Besides, a new approach based on sudden substantial changes in the displacement of marked nodes is proposed to identify the slope failure in SSRFEM. Finally, the modified SSRFEM is applied to compute the FOS of a slope example.
 
Key Words
    wetting-drying cycles; shear strength reduction finite element method; modification; factor of safety; soil slope
 
Address
(1) Yiliang Tu, Zuliang Zhong, Weikun Luo, Xinrong Liu, Sui Wang:
College of Civil Engineering, Chongqing University, Chongqing 400045, China;
(2) Yiliang Tu, Zuliang Zhong, Weikun Luo, Xinrong Liu, Sui Wang:
Key Laboratory of New Technology for Construction of Cities in Mountain Area (Chongqing University), Ministry of Education, Chongqing, 400045, China;
(3) Zuliang Zhong
Department of Architecture and Civil Engineering, Logistical Engineering University, Chongqing, 400041, China.
 

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