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| Study on the correlation between the lateral facing deformation and factor of safety for tiered GRS wall |
| 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 lateral facing deformation characteristics and the relationship between the maximum deformation and stability of GRS wall in a tiered configuration，a validated finite difference numerical method was used to compute the maximum lateral facing deformation and the maximum tensile forces mobilized in each layer reinforcement，which were utilized to determine the factor of safety(FS) of the corresponding GRS walls，and then a parametric study was conducted to analyze the effect of properties of backfill and foundation soil，reinforcement properties，and configuration mode of tiered GRS wall on deformation and stability. The computed results showed that：(1) The other parameters of two-tiered GRS walls remain unchanged，increasing the friction angle or cohesion，the GRS wall becomes more stable，and the maximum lateral facing deformation and the maximum tensile force mobilized in reinforcement decrease and the FS increases. Increasing reinforcement length in upper or lower wall results in a reduction of lateral facing deformation and an increase of FS，and when reinforcement lengths in upper or lower wall reach the critical length，e.g. 0.7H(H，the total wall height) or 0.6H，the maximum lateral facing deformation and FS values tend to be stable. Reducing the vertical spacing of reinforcement or increasing the reinforcement stiffness caused a decrease in lateral facing deformation and an increase in FS.(2) For a multitiered GRS wall with equally individual wall height，with the increase of the offset distance，the maximum lateral deformation tends to decrease and then to be stable. The critical offset distance，beyond which the adjacent tiers wall functions independently，is 1.2 times the individual wall height for the recommended friction angle(? = 34°) by guidelines.(3) For a multitiered GRS wall with the same total wall height and normalized offset distance，increasing the number of tiers wall results in a decrease in maximum lateral deformation and FS，which then tend to be increasing when the number of tiers reaches a specified value. When the wall height ratio of the upper and lower wall is no great than 1，the change of the ratio does not affect remarkably the lateral facing deformation. Once the upper wall height is greater than the lower wall，the maximum lateral facing deformation in the upper wall increases significantly. In addition，increasing the total wall height causes an obvious increase in lateral facing deformation，and consequently，the FS decreases.(4) Based on the calculation results of two-tiered GRS walls，an empirical function is proposed to build the correlation between FS，normalized maximum lateral deformation，and normalized offset distance. It is helpful for engineers to evaluate the stability of a two-tiered GRS wall via the quantified maximum lateral deformation.
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