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| Correlation between lateral facing deformation and factor of
safety for tiered GRS walls |
| GAO Shan1，XIAO Chengzhi1，DING Luqiang1，YU Hongxing2 |
| (1. School of Civil and Transportation Engineering，Hebei University of Technology，Tianjin 300401，China；
2. Tianjin Highway Development and Service Center，Tianjin 300170，China) |
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Abstract To investigate the behavior of lateral facing deformation of a geosynthetic-reinforced soil(GRS) wall in a tiered configuration and to quantify the correlation between the maximum lateral facing deformation and the factor of stability(FS) of the corresponding wall，a validated finite difference numerical method was used to calculate the lateral facing deformation and the maximum tensile force mobilized in each layer reinforcement，which were inputted in the shear strength reduction(SSR) method to determine the factor of safety of the tiered GRS walls. Further，a parametric study was performed to analyze the effect of properties of backfill and foundation soil，reinforcement properties，and configuration mode of the tiered GRS walls on the lateral facing deformation and the factor of stability. The results show that：(1) for the two-tiered GRS walls with other parameters remaining constant，an increase in friction angle or cohesion of the backfill causes the enhancement of the wall stability，and thus decreases the maximum lateral facing deformation and the maximum tensile forces mobilized in the reinforcement layers. Increasing reinforcement length in upper or lower wall results in a reduction of lateral facing deformation and an increase of FS. When the reinforcement length in upper or lower wall reach the critical value，e.g. 0.7H (H is the total wall height) or 0.6H，the maximum lateral facing deformation and FS value tend to be stable. Besides，reducing the vertical spacing of reinforcement or increasing the reinforcement stiffness causes a decrease in lateral facing deformation and an increase in FS. (2) Increasing the offset distance for a multitiered GRS wall with equally individual wall height，the maximum lateral facing deformation tends to decrease and then to be stable. The critical offset distance，beyond which each tier wall functions independently，is determined to be the 1.2 times the individual wall height for the backfill with a recommended friction angle ? = 34° by guidelines. (3) The maximum lateral facing deformation and the corresponding FS for a multitiered GRS wall with the same total wall height and normalized offset distance decrease with the number of tiers，and then tend to increase once the number of tiers reaches a certain value. When the wall height ratio of the upper and lower walls is no great than 1，the change of the wall height ratio does not affect remarkably the lateral facing deformation. In addition，as the total height of the two-tiered GRS walls increases，the maximum lateral facing deformation increases and the FS values decrease. (4) An empirical function based on the numerical results was proposed to establish the correlation among FS，the normalized maximum lateral facing deformation and the normalized offset distance. It is helpful for engineers in practice to evaluate quantitively the stability of a two-tiered GRS wall based on the specified maximum lateral facing deformation.
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2023, Vol. 42 
