MSE-LASR Manual [MSE Wall Fills – A Framework for Use of Local Available Sustainable Fills (LASR)]

Document Info

Title: Mechanically Stabilized Earth (MSE) Wall Fills - A Framework for Use of Local Available Sustainable Resources (LASR)

Document Type: Manual

Authored By: Naresh C. Samtani, PE, PhD, and Edward A. Nowatzki, PE, PhD

Sponsoring Agency: Federal Highway Administration (FHWA)

Abstract

Mechanically Stabilized Earth (MSE) walls have been used in the United States as earth retention systems since the 1970s. They are also widely used throughout the world. Select fills are commonly specified for the reinforced soil zone. Typically, transportation agencies use select fills that limit the fines to 15% and plasticity index (PI) to 6 along with other limitations on particle sizes and electrochemical properties. Often such select fill materials are not available locally and their import to a jobsite, environmental impacts, and associated disposal of local native soils increases project costs leading to consideration of alternative earth retention systems. The intent of this manual is to establish a risk-based framework for the use of local available sustainable resources (LASR) in the reinforced zone of MSE walls. MSE walls using LASR are herein termed MSE-LASR walls. The ultimate goal for establishing this framework is the development of design and construction guidelines for projects in the context of the Load and Resistance Factor Design (LRFD) approach in the Bridge Design Specifications (BDS) of the American Association of State Highway and Transportation Officials (AASHTO). The framework presented herein allows for the performance of future studies as appropriate to ensure the guidelines are applicable to the specific needs of an agency based on the range of possible LASR materials that the agency encounters within its jurisdiction.

This manual presents a summary of a comprehensive literature review on the use of LASR fills in MSE walls. Several issues were identified, e.g., drainage, post-construction deformations, maintenance, etc. The manual has been organized in the context of risks associated with various aspects of using LASR fills. Based on an understanding of the risks associated with the use of LASR materials, a framework is presented for the development of guidelines in the context of AASHTO-LRFD for use in the design and construction of MSE-LASR walls. Considerations related to design criteria, constructability, practical deployment of framework, future studies etc. are presented. User tools and an example calculation are presented.