Dissertation/Thesis Abstract

Geosynthetic Reinforced Retaining Walls with Limited Fill Space under Static Footing Loading
by Kakrasul, Jamal Ismael, Ph.D., University of Kansas, 2018, 346; 10746015
Abstract (Summary)

Geosynthetic reinforced retaining (GRR) walls, which typically consist of reinforced soil mass, facing units, and retained fill, are extensively used for highways, bridge abutments, and service roads throughout the world. In recent decades, GRR walls have been increasingly built with limited fill space, which has posed challenges for designing such walls with satisfactory performance, especially under surface loading, such as bridge foundations. Since the GRR walls with limited fill space are retaining walls under special conditions, only limited information related to such walls is available in the literature and therefore their performance has not been well understood. The objective of this study was to evaluate the performance of limited fill space GRR walls subjected to static footing loading.

To fulfill the above research objective, a comprehensive experimental study and numerical analysis were conducted. The experimental study included a series of laboratory model tests to investigate the performance of GRR walls constructed with limited fill space subjected to strip footing loading. The devised experimental program consisted of 11 model tests with different retained medium distances, geosynthetic-reinforced fill widths, footing offset distances, and reinforcement layouts.

The numerical analysis was performed by using the continuum mechanics-based program FLAC 2D Version 8.0 to verify the experimental results. In the numerical analysis, backfill soil was modeled as a linearly elastic perfectly plastic material with the Mohr Coulomb (MC) failure criterion. The wall facing, the stable retained medium, and the foundation were modeled as a linearly elastic material. A strip element was utilized to simulate the reinforcement and modeled as a linearly elastic perfectly plastic material. The lateral displacement of the wall facing, the footing settlement, the vertical earth pressures, lateral earth pressures, and the maximum strains in the reinforcement were computed by the numerical analysis under the applied footing loads and compared to the results from the experimental tests. The results obtained from the numerical analysis generally agreed with those measured from the experimental tests.

In addition, a numerical parametric study was conducted to assess the factors influencing the performance of GRR walls with limited fill space subjected to static footing loading. The influence factors consisted of the reinforced fill width (reinforcement length), the reinforcement rear connection, the footing size, the footing offset distance, the stiffness of reinforcement, the friction angle of the backfill soil, and the wall height. The parametric study showed that the maximum lateral displacement of the wall facing, and the footing settlement increased with the reduction in the reinforced fill width, the friction angle of the backfill soil, and the footing offset distance. In contrast, the maximum lateral displacement of the wall facing, and the footing settlement decreased with an increase in the reinforcement stiffness, the footing offset distance, and the decrease in the footing size. The parametric study also showed that the connection of the reinforcement to the stable medium at rear, bending-upward the reinforcement around the back of the reinforced fill and overlapped the reinforcement from the back of the reinforced fill resulted in considerable reduction in the maximum lateral displacement of the wall facing and the footing settlement. The maximum strain in the reinforcement increased with the reduction in the reinforced fill width, the friction angle of the backfill soil, and the footing offset distance. However, the maximum strain in the reinforcement decreased with the increase in the reinforcement stiffness, the decrease in the footing size and the footing offset distance. Additionally, the vertical earth pressures computed on the wall along the wall facing of the wall models were lower than those computed along the centerline of the footing under all the applied footing loads. Also, the vertical earth pressures computed on the wall along the wall facing of wall models were generally lower than those calculated by the 2:1 distribution method. However, the vertical earth pressures computed along the centerline of the footing along were generally higher than those calculated by the 2:1 distribution method. Similarly, the lateral earth pressures computed on the wall facing of wall models were lower than those calculated by the exiting methods (i.e., Rankine’s active earth pressure theory and Janssen’s equation with the 2:1 distribution method). However, the lateral earth pressures calculated using Janssen’s equation showed better agreement with the lateral earth pressures computed by the numerical analysis as compared to those calculated using Rankine’s theory. (Abstract shortened by ProQuest.)

Indexing (document details)
Advisor: Han, Jie
Commitee: Cai, Hongyi, Hui, Rongqing, Parsons, Robert L., Schrock, Steven D.
School: University of Kansas
Department: Civil, Environmental & Architectural Engineering
School Location: United States -- Kansas
Source: DAI-B 79/08(E), Dissertation Abstracts International
Source Type: DISSERTATION
Subjects: Geotechnology, Geological engineering, Civil engineering
Keywords: Earth pressures, Footing settlement, Geosynthetic, Limited space, Reinforced soil retainig walls, Scale effect
Publication Number: 10746015
ISBN: 9780355777994
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