Reinforced Earth Wall (RE Wall): RE wall construction important guidelines

 Reinforced Earth Wall (RE Wall): A Robust Solution for Earth Retention

Introduction

Reinforced Earth Wall (RE Wall), also known as a Reinforced Soil (RS) wall, is an innovative and efficient solution for earth retention and slope stabilization. 

This article delves into the concept of RE Walls, explores the essential elements of their construction, outlines the construction sequence, discusses testing frequencies, addresses the causes of failure, and highlights the importance of construction tolerances.

What is the Reinforced Earth Wall (RE Wall)?

A Reinforced Earth Wall is a mechanically stabilized earth (MSE) retaining structure that combines the principles of soil mechanics and the strength of reinforcing materials to create a robust and durable structure. 

It consists of a facing system, typically precast concrete panels, connected to the reinforced soil mass behind it.

Elements of Reinforced Soil Wall

Precast RE Panel

The facing system of an RE Wall comprises precast concrete panels. 

These panels, with specific geometric configurations, interlock with each other to create a stable facing surface. 

Precast Reinforced panel 

They are typically manufactured with high-quality concrete and have a variety of aesthetic finishes.

Reinforced Earth Fill

The reinforced soil mass is formed by compacting granular fill material, such as crushed stone or aggregate, in thin horizontal layers. 

This fill material provides the necessary structural stability to the RE Wall.

Drainage Media/Filter Media

To ensure effective drainage and prevent the buildup of hydrostatic pressure behind the wall, a drainage or filter media is placed within the reinforced soil mass. 

This material allows water to flow freely while retaining the fill material.

Reinforcement Material

The reinforcement elements in an RE Wall are typically high-strength geosynthetic strips or grids. 

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These materials are designed to distribute and resist tensile forces within the reinforced soil mass. 

They provide cohesion and increase the overall stability of the structure.

Frequency of Testing for RE Wall Construction

During the construction of an RE Wall, it is crucial to conduct regular testing to ensure the integrity and quality of the structure. 

The frequency of testing may vary depending on project specifications and local regulations. 

Common testing activities include compaction tests, pullout tests for reinforcement, and facing panel quality inspections.

RE Wall/RS Wall Friction Slab

The friction slab is a critical component of an RE Wall. 

It is a horizontal concrete or steel plate placed at the base of the wall to increase the resistance against sliding forces. 

The friction slab interacts with the reinforced soil mass to provide stability and prevent horizontal movement.

Reinforced Earth Wall Construction Sequence

Excavation and Site Preparation

The construction site is cleared and prepared for excavation. Any unsuitable soil is removed, and the area is leveled.

Foundation Preparation

The foundation is excavated and leveled, ensuring a stable and uniform base for the RE Wall. Geotextile fabric may be plac

ed to separate the foundation soil from the fill material.

Compaction of Reinforced Fill

The granular fill material is placed and compacted in thin layers, typically 6 to 12 inches thick. Each layer is compacted to achieve the desired density using compaction equipment.

Placing of Reinforcement

The reinforcement material, such as geosynthetic strips or grids, is installed within the compacted fill at the specified vertical spacing. Careful attention is given to ensure proper alignment and anchorage of the reinforcement.

Facing Panel Installation

Precast concrete facing panels are installed, interlocked, and connected to the reinforcement. The panels provide an aesthetic and protective facing to the RE Wall.

Backfilling and Compaction

The remaining voids between the facing panels and the reinforcement are filled with granular material. This material is compacted to achieve the required density and ensure structural stability.

Drainage and Filter Media

A layer of drainage or filter material is placed behind the facing panels to promote proper water drainage and prevent hydrostatic pressure buildup.

RE Wall Construction Tolerances

To ensure the structural integrity and aesthetic appeal of an RE Wall, specific tolerances must be maintained during construction. These tolerances include alignment of facing panels, verticality of the wall, and surface smoothness. Strict adherence to tolerances ensures a visually pleasing and structurally sound finished product.

Causes of Failure of Reinforced Earth Wall

Poor Design

Inadequate design that does not consider the site conditions, soil properties, and anticipated loads can lead to structural failure of the RE Wall.

Insufficient Reinforcement

Improper placement or inadequate reinforcement within the soil mass can result in insufficient strength and stability, leading to wall deformation or collapse.

Inadequate Drainage

Lack of proper drainage behind the wall can cause water accumulation, increasing hydrostatic pressure and potentially leading to instability and erosion.

Construction Errors

Mistakes during construction, such as improper compaction, incorrect reinforcement placement, or inadequate facing panel interlocking, can compromise the structural integrity of the RE Wall.