Development and verification of a numerical model for the analysis of geosynthetic-reinforced soil segmental walls under working stress conditions

2005 ◽  
Vol 42 (4) ◽  
pp. 1066-1085 ◽  
Author(s):  
Kianoosh Hatami ◽  
Richard J Bathurst
Keyword(s):  
Numerical Model ◽  
Constitutive Models ◽  
Reinforced Soil ◽  
Stress Conditions ◽  
Soil Reinforcement ◽  
Lagrangian Analysis ◽  
Elastic Plastic ◽  
Geosynthetic Reinforced Soil ◽  
Working Stress ◽  
Good Agreement

The paper describes a numerical model that was developed to simulate the response of three instrumented, full-scale, geosynthetic-reinforced soil walls under working stress conditions. The walls were constructed with a fascia column of solid modular concrete units and clean, uniform sand backfill on a rigid foundation. The soil reinforcement comprised different arrangements of a weak biaxial polypropylene geogrid reinforcement material. The properties of backfill material, the method of construction, the wall geometry, and the boundary conditions were otherwise nominally the same for each structure. The performance of the test walls up to the end of construction was simulated with the finite-difference-based Fast Lagrangian Analysis of Continua (FLAC) program. The paper describes FLAC program implementation, material properties, constitutive models for component materials, and predicted results for the model walls. The results predicted with the use of nonlinear elastic-plastic models for the backfill soil and reinforcement layers are shown to be in good agreement with measured toe boundary forces, vertical foundation pressures, facing displacements, connection loads, and reinforcement strains. Numerical results using a linear elastic-plastic model for the soil also gave good agreement with measured wall displacements and boundary toe forces but gave a poorer prediction of the distribution of strain in the reinforcement layers.Key words: numerical modelling, retaining walls, reinforced soil, geosynthetics, FLAC.

scholarly journals Deformation of Geosynthetic Reinforced Soil Structures by Design, in the Lab and in the Field

2011 ◽  
Vol 57 (2) ◽  
pp. 153-171
Author(s):  
G. Heerten
Keyword(s):  
Field Tests ◽  
Seismic Loading ◽  
Reinforced Soil ◽  
Soil Reinforcement ◽  
Design Code ◽  
Geosynthetic Reinforced Soil ◽  
Soil Structures ◽  
The Usa ◽  
New Research ◽  
Reinforcement Interaction

Abstract Green-geo-engineering with geosynthetic reinforced soil structures is of increasing practice around the world. Poland is among the leading countries with the third biggest geogrid market in Europe. The German EBGEO 2010 Guideline for Soil Reinforcement with Geosynthetics as first European Guideline for Geosynthetics linked to the Eurocode 7, and the new design code for Japanese railway structures under seismic loading are introduced. New research results from the Geotechnical Institute of the RWTH Aachen, Germany, dealing with the soil/reinforcement interaction and new approaches for design codes for the reinforcement of base courses in traffic areas based on lab and field tests in the USA are presented.

scholarly journals Evaluating the Performance of Geosynthetic Reinforced Soil-Integrated Bridge System (GRS-IBS) under Working Stress Condition

2019 ◽  
Vol 271 ◽  
pp. 02001
Author(s):  
Murad Abu-Farsakh ◽  
Allam Ardah ◽  
George Voyiadjis
Keyword(s):  
Strain Distribution ◽  
Reinforced Soil ◽  
Span Length ◽  
Linear Elastic ◽  
Geosynthetic Reinforced Soil ◽  
Working Stress ◽  
Spacing Ratio ◽  
Coulomb Model ◽  
Bridge System

This paper evaluates the performance of geosynthetic reinforced soil-Integrated Bridge System (GRS-IBS) in terms of lateral facing deformation and strain distribution along geosynthetics. Simulations were conducted using 2D PLAXIS program. The hardening model proposed by Schanz et al. [1] was used to simulate the behavior of backfill material; the backfill-reinforcement interface was simulated using Mohr-Coulomb model, and the reinforcement and facing block were simulated using linear elastic models. The numerical model was verified using the results of a case study conducted at Maree Michel GRS-IBS, Louisiana. Parametric study was carried out to investigate the effects of span length, reinforcement spacing, and reinforcement stiffness on the performance of GRS-IBS. The results indicate that span length have significant impact on strain distribution along geosynthetics and lateral facing deformation. The reinforcement stiffness has significant impact on the GRS-IBS behavior up to a certain point, beyond which the effect tends to decrease contradictory to reinforcement spacing that has a consistent relationship between the GRS-IBS behavior and reinforcement spacing. The results also indicate that reinforcement spacing has higher influence on the lateral facing deformation than the reinforcement stiffness for the same reinforcement strength/spacing ratio (Tf/Sv) due to the composite behavior of closely reinforcement spacing.

A new working stress method for prediction of reinforcement loads in geosynthetic walls

2003 ◽  
Vol 40 (5) ◽  
pp. 976-994 ◽  
Author(s):  
T M Allen ◽  
Richard J Bathurst ◽  
Robert D Holtz ◽  
D Walters ◽  
Wei F Lee
Keyword(s):  
Limit Equilibrium ◽  
Limit State ◽  
Reinforced Soil ◽  
Soil Reinforcement ◽  
New Method ◽  
Internal Stability ◽  
Working Stress ◽  
Soil Walls ◽  
Stiffness Method ◽  
Reinforced Soil Walls

Proper estimation of soil reinforcement loads and strains is key to accurate internal stability design of reinforced soil structures. Current design methodologies use limit equilibrium concepts to estimate reinforcement loads for internal stability design of geosynthetic and steel reinforced soil walls. For geosynthetic walls, however, it appears that these methods are excessively conservative based on the performance of geosynthetic walls to date. This paper presents a new method, called the K-stiffness method, that is shown to give more accurate estimates of reinforcement loads, thereby reducing reinforcement quantities and improving the economy of geosynthetic walls. The paper is focused on the new method as it applies to geosynthetic walls constructed with granular (noncohesive, relatively low silt content) backfill soils. A database of 11 full-scale geosynthetic walls was used to develop the new design methodology based on working stress principles. The method considers the stiffness of the various wall components and their influence on reinforcement loads. Results of simple statistical analyses show that the current American Association of State Highway and Transportation Officials (AASHTO) Simplified Method results in an average ratio of measured to predicted loads (bias) of 0.45, with a coefficient of variation (COV) of 91%, whereas the proposed method results in an average bias of 0.99 and a COV of 36%. A principle objective of the method is to design the wall reinforcement so that the soil within the wall backfill is prevented from reaching a state of failure, consistent with the notion of working stress conditions. This concept represents a new approach for internal stability design of geosynthetic-reinforced soil walls because prevention of soil failure as a limit state is considered in addition to the current practice of preventing reinforcement rupture.Key words: geosynthetics, reinforcement, walls, loads, strains, design, K-stiffness method.

Influence of toe restraint on reinforced soil segmental walls

2010 ◽  
Vol 47 (8) ◽  
pp. 885-904 ◽  
Author(s):  
Bingquan Huang ◽  
Richard J. Bathurst ◽  
Kianoosh Hatami ◽  
Tony M. Allen
Keyword(s):  
Limit Equilibrium ◽  
Retaining Wall ◽  
Shear Stiffness ◽  
Reinforced Soil ◽  
Lagrangian Analysis ◽  
Interface Shear ◽  
Operational Conditions ◽  
Working Stress ◽  
Current Limit ◽  
Stiffness Method

A verified fast Lagrangian analysis of continua (FLAC) numerical model is used to investigate the influence of horizontal toe stiffness on the performance of reinforced soil segmental retaining walls under working stress (operational) conditions. Results of full-scale shear testing of the interface between the bottom of a typical modular block and concrete or crushed stone levelling pads are used to back-calculate toe stiffness values. The results of numerical simulations demonstrate that toe resistance at the base of a reinforced soil segmental retaining wall can generate a significant portion of the resistance to horizontal earth loads in these systems. This partially explains why reinforcement loads under working stress conditions are typically overestimated using current limit equilibrium-based design methods. Other parameters investigated are wall height, interface shear stiffness between blocks, wall facing batter, reinforcement stiffness, and reinforcement spacing. Computed reinforcement loads are compared with predicted loads using the empirical-based K-stiffness method. The K-stiffness method predictions are shown to better capture the qualitative trends in numerical results and be quantitatively more accurate compared with the AASHTO simplified method.

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