Facing of geosynthetic reinforced soil structures

A study was undertaken to explore the role of facing in Geosynthetic Reinforced Soil (GRS) structures from a variety of perspectives and to develop a new design protocol that considers environmental and aesthetic considerations alongside traditional strength and service performance metrics. This topic of facing is an important one as industry moves closer to accepting the inherent differences between internally-stabilized GRS structures and externally-stable geosynthetic mechanically stabilized earth (GMSE) structures. While construction materials and methods are similar for the two design options, a major difference is that the facing elements for GRS are not structures and exist mostly to aid in construction and to prevent sloughing. GMSE structures require a strong connection between reinforcement and facing for the system to remain stable.;To achieve the goal of a more holistic design protocol, the following three tasks were completed:;1) Establish the role of facing on load-deformation behavior of GRS structures: The role of facing was established by: a) summarizing existing results from full-scale, laboratory-scale, and analytical models; and b) developing a new experimental approach to determine how facing stiffness during and post-construction can affect behavior.;Major conclusions: The load-deformation response of GRS structures differ greatly from that of GMSE. With or without facing, structures built with spacing less than 0.3 meters exhibits a stiffer response than GMSE structures with similar geometry.;2) Define sustainability of GRS structures: A new Life Cycle Assessment (LCA) framework was developed for comparing GRS and GMSE structures. Additionally, the feasibility of incorporating recycled materials into GRS facing is presented.;Major conclusions: The flexibility in GRS design leads to opportunity for engineers to create a more sustainable end product, not just in materials used but also in required equipment and construction methods.;3) Establish relevant aesthetic considerations: Both strictly aesthetic and functional aesthetic considerations are presented. Recommendations are made based on the location of the structure (i.e. natural, urban, transportation corridor).;Major conclusions: A wider variety of facing materials results in an aesthetic treatment specific to the location of a wall instead of proprietary systems not catered to individual projects. Additionally, there is opportunity to incorporate some functionality to the aesthetic, specifically in highway corridors.;The end result of this study is a new design method that includes LRFD factors calibrated to an existing design method, a method for quantifying the environmental impact of a GRS structure, and framework for determining the most appropriate facing treatment.