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Geomechanics and Engineering
  Volume 23, Number 3, November10 2020, pages 207-215
DOI: http://dx.doi.org/10.12989/gae.2020.23.3.207
 


Passive earth pressure for retaining structure considering unsaturation and change of effective unit weight of backfill
Li Zheng, Lin Li, Jingpei Li and De'an Sun

 
Abstract
    This paper presents a kinematic limit analysis for passive earth pressure of rigid retaining structures considering the unsaturation of the backfill. Particular emphasis in the current work is focused on the effects of the spatial change in the degree of saturation on the passive earth pressure under different steady-infiltration/evaporation conditions. The incorporation of change of effective unit weight with degree of saturation is the main contribution of this study. The problem is formulated based on the log-spiral failure model rather than the linear wedge failure model, in which both the spatial variations of suction and soil effective unit weight are taken into account. Parametric studies, which cover a wide range of flow conditions, soil types and properties, wall batter, back slope angle as well as the interface friction angle, are performed to investigate the effects of these factors on the passive pressure and the corresponding shape of potential failure surfaces in the backfill. The results reveal that the flow conditions have significant effects on the suction and unit weight of the clayey backfill, and hence greatly impact the passive earth pressure of retaining structures. It is expected that present study could provide an insight into evaluation of the passive earth pressure of retaining structures with unsaturated backfills.
 
Key Words
    passive earth pressure; retaining structure; unsaturation; suction; log spiral failure model
 
Address
Li Zheng, Lin Li and Jingpei Li: Department of Civil Engineering, Tongji University, Shanghai 200092, China

De'an Sun: Department of Civil Engineering, Shanghai University, Shanghai 200444, China
 

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