Static structural behavior of geogrid reinforced soil retaining walls with a deformation buffer zone

Abstract

To understand the structural behavior of geogrid reinforced soil retaining walls (GRSW) with a deformation buffer zone (DBZ) under static loads, the model tests and the numerical simulations were conducted to obtain the wall face horizontal displacement, vertical and horizontal soil pressures, and geogrid strains. Results showed that compared with the common GRSW, the horizontal displacement of GRSW with DBZ decreased, and the horizontal soil pressure acting on the face panel of GRSW with DBZ increased. The vertical and horizontal soil pressures showed a nonlinear distribution along the reinforcement length, and the value was smaller near the face panel. The horizontal soil pressure acting on the face panel of GRSW with DBZ was greater than that of the common GRSW in the middle portion. The cumulative strain of the geogrid had a single-peak distribution along its length; the maximum strain of the geogrid was 0.45%, the maximum tension was approximately 29.12% of ultimate tensile strength.

Introduction

Geosynthetic reinforced soil retaining walls are increasingly applied in highway and railway construction because of their high strength, small deformation, improved earthquake resistance, and deformation accommodation. They have some superiorities in saving the land and environmental protection. The reinforced soil retaining wall can adopt fabricated construction to speed up the construction pace. The advantages above can result in great economic and social benefits.

In recent decades, many laboratory and field tests have analyzed the deformation and stress characteristics of reinforced soil retaining walls with different types of face and under different surcharge loads. The post-construction displacement of the reinforced soil wall is about 0.3%–1% H (Latha and Manju, 2016; Yang et al., 2012, 2014; Zevgolis, 2018). Bathurst et al. (2010) compared the measured value with the recommended value by different design specifications and observed that the FHWA and AASHTO design specifications gave more rational limits. The coefficient of lateral earth pressure acting on face panel is 0.6–1.3 and can be divided into three zones, the earth pressure coefficient decreases with an increasing reinforcement ratio (Jacobs et al., 2016; Udomchai et al., 2017). The distribution of the earth pressure for geobag retaining walls is within the range of Rankine's and Coulomb's earth pressure after construction (Shin et al., 2017). The evolution of reinforcement strain and failure surface is also revealed (Balakrishnan and Viswanadham, 2016; Krystyna, 2005; Xue et al., 2014; Xiao et al., 2016). And the deformation modes are also different among reinforced soil retaining walls (Correia et al., 2012; Liu et al., 2011; Liu, 2012; Ren et al., 2018; Wang et al., 2014, 2016; Yu and Bathurst, 2017), which the maximum cumulative horizontal displacement occurred at different portions.

Numerical analysis is also important for understanding the characteristics of reinforced soil retaining walls and has elucidated the distributions and controlling factors for the stability of reinforced soil retaining walls. Reinforcement stiffness and length were identified as influential parameters affecting the horizontal movement at a specific MSE wall height, and the maximum displacement and tensile load in the reinforcement increased with an increase in the reinforcement spacing (Kibria et al., 2014; Ling and Leshchinsky, 2003; Marián et al., 2016). The currently available design guideline tends to over-estimate the surcharge load-induced reinforcement forces, and the surcharge load-induced reinforcement strains exponentially decrease with depth (Yoo and Kim, 2008). Some studies provide detail on how material properties are selected and how computer modeling is carried out (Purkar and Kute, 2015; Rabie, 2016; Yu et al., 2016). Barani et al. (2018) presented a new approach for back analysis of a geogrid reinforced soil wall failure.

Research into the evolution of wall structural behavior has aimed to control the wall's deformation and guarantee the wall's strength, providing important information for the design and construction of reinforced soil retaining walls.

Deformation control is critical for flexible reinforced soil retaining walls. In conventional reinforced soil retaining walls, the reinforced soil is in contact with the panel. Lateral soil pressure acts on the panel directly, which results in the panel horizontal displacement. If the horizontal displacement is large, it is negative for structural stability and great settlement of the retaining wall will occur, impacting its practical applications. However, a deformation buffer zone can be installed between the reinforced soil and the panel to relieve horizontal displacement. The deformation buffer zone is also reinforced soil. The model structure is shown in Fig. 1. Model tests of GRSW with DBZ have been performed and the aim is to evaluate the stress and deformation characteristics during construction and under top loading after construction.