Geosynthetic Reinforced Soil Integrated Bridge Research Articles

Deformation Responses of a Geosynthetic Reinforced Soil-Integrated Bridge System Under Static Loading and Sensitivity Analysis of Influential Factors Based on the Improved Grey Relational Method

A numerical parametric study is conducted to evaluate the effects of various parameters on the deformation responses of a geosynthetic reinforced soil-integrated bridge system (GRS-IBS) under static load. The investigated parameters include the abutment height, reinforcement spacing, reinforcement length, reinforcement stiffness, bridge load, and backfill internal friction angle. The improved grey relational method is used to investigate the sensitivity of influential factors on the deformation responses of the GRS-IBS. The simulation results indicate that the abutment height, reinforcement spacing, and bridge load have a significant impact on the performance of the GRS-IBS with respect to lateral displacement and settlement, while the effects of reinforcement length, reinforcement stiffness, and backfill internal friction angle on the deformation behavior of the abutment are negligible. Differential settlements between the girder and approach are minimal under all conditions. The potential failure envelope of the GRS-IBS exhibits a “L” shaped configuration where the potential failure surface starts beneath the inner edge of the strip footing, extending vertically downward to half of the wall height and further bifurcating toward the strip footing and the toe of the wall. The results of the improved grey relational analysis show that reinforcement spacing is the most sensitive to the lateral displacement of the GRS-IBS. The abutment height and bridge load are more sensitive to abutment deformation than other influential factors. These three parameters are crucial to the deformation behavior and should be given primary consideration when designing a GRS-IBS.

Use of geosynthetic reinforced soil-integrated bridge system to alleviate settlement problems at bridge approach: A review

Bump problems at the bridge approach cause riding discomfort and result in safety issue to the road users. The Geosynthetic Reinforced Soil-Integrated Bridge System (GRS-IBS) is a recent bridge approach construction system that connects the bridge deck and roadways without joints and bearings, thus capable to eliminate the bump problems. This system is gaining popularity for low to medium bridge construction due to its relatively faster, lower cost, and simple construction process. The GRS abutment is a composite geotechnical structure with internally supported reinforcement. A close spacing reinforcement of 0.2–0.3 m in between the compacted granular backfill of high shear resistance has improved the bearing capacity of the GRS abutment, hence capable to support the bridge loads directly. In this paper, a thematic literature review on the bump problems and GRS-IBS system is presented. Summaries of previous studies are tabulated and discussed, inclusive of case studies, physical models, numerical models, and key factors affecting the performance of GRS-IBS. Limitations posed to this system are also provided at the end of this article. The review and summary of this paper are expected to provide meaningful information to the readers.

Numerical simulation of dynamic response of geosynthetic-reinforced soil-integrated bridge system

Numerical simulation of dynamic response of geosynthetic-reinforced soil-integrated bridge system

Numerical Analyses on the Behavior of Geosynthetic-Reinforced Soil: Integral Bridge and Integrated Bridge System

Geosynthetic-reinforced soil (GRS) technology has been used worldwide since the 1970s. An extension to its development is the application as a bridge abutment, which was initially developed by the Federal Highway Administration (FHWA) in the United States, called the GRS—integrated bridge system (GRS-IBS). Now, there are several variations of this technology, which includes the GRS Integral Bridge (GRS-IB) developed in Japan in the 2000s. In this study, the GRS-IB and GRS-IBS are examined. The former uses a GRS bridge abutment with a staged-construction full height rigid (FHR) facing integrated to a continuous girder on top of the FHR facings. The latter uses a block-faced GRS bridge abutment that supports the girders without bearings. In addition, a conventional integral bridge (IB) is considered for comparison. The numerical analyses of the three bridges using Plaxis 2D under static and dynamic loadings are presented. The results showed that the GRS-IB exhibited the least lateral displacement (almost zero) at wall facing and vertical displacements increments at the top of the abutment compared to those of the GRS-IBS and IB. The presence of the reinforcements (GRS-IB) reduced the vertical displacement increments by 4.7 and 1.3 times (max) compared to IB after the applied general traffic and railway loads, respectively. In addition, the numerical results revealed that the GRS-IB showed the least displacement curves in response to the dynamic load. Generally, the results revealed that the GRS-IB performed ahead of both the GRS-IBS and IB considering the internal and external behavior under static and dynamic loading.

Prediction equations for estimating maximum lateral displacement and settlement of geosynthetic reinforced soil abutments

Abstract The Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS), which consists of closely-spaced layers of geosynthetic reinforcement and compacted granular fill material, is a fast, sustainable and cost-effective method for bridge support. The in-service performance of this innovative bridge support system is largely evaluated through the vertical and horizontal deformations of the GRS abutments. This paper presents the development of nonlinear equations for estimating the maximum lateral displacement and settlement of GRS abutments. The parameters that are considered in the prediction equations include abutment geometry (height, facing batter and foundation width), backfill friction angle, reinforcement characteristics (stiffness, spacing, and length), and applied static loads from 50 to 400 kPa. In the development of the prediction equations, a parametric study was first conducted using a validated finite difference numerical model. The results of the parametric study were then used to conduct a regression analysis to develop the equations for estimating the maximum lateral displacement and settlement of GRS abutments under service loads. The equations were validated using three case studies. The developed prediction equations can contribute to a better understanding and enable simple calculations in designing these structures.

Comparison of Field Behavior with Results from Numerical Analysis of a Geosynthetic Reinforced Soil Integrated Bridge System Subjected to Thermal Effects

When subjected to ambient daily temperature fluctuations, a 109.5 ft-long geosynthetic reinforced soil integrated bridge system (GRS-IBS) was observed to undergo cyclic straining of the superstructure. The upper and lower reaches of the superstructure experienced the highest and lowest strain fluctuation, respectively. These non-uniform strains impose not only axial loading of the superstructure but also bending. Pure axial loading in a horizontal superstructure will cause the footings to slide. However, bending in the superstructure will cause the footings to rotate thereby inducing cyclic fluctuations of the vertical pressure beneath the footing and also lateral pressure behind the end walls. Measured vertical footing pressure closest to the stream experienced the greatest daily pressure fluctuation (≈ 2,500–3,000 psf), while that nearest the end wall experienced the least. The toe pressure fluctuations seem rather large. That these large vertical pressure fluctuations are observed in a tropical climate like Hawaii when no other GRS-IBS in temperate regions has reported the same (or perhaps higher fluctuation) is indeed surprising. The larger these pressures are, the greater the likelihood of inducing cyclic-induced deformations of the GRS abutment. A finite element analysis of the same GRS-IBS was performed by applying an equivalent temperature and gradient to the superstructure over the coldest and hottest periods of a day to see if the field measured values of pressures are reasonable and verifiable, which indeed they were. This methodology is novel in the sense that the effects of axial load and bending of the superstructure are simulated using measured strains rather than measured temperatures.

Seismic performance of a whole Geosynthetic Reinforced Soil – Integrated Bridge System (GRS-IBS) in shaking table test

A scaled plane-strain shaking table test was conducted in this study to investigate the seismic performance of a Geosynthetic Reinforced Soil-Integrated Bridge System (GRS-IBS) with a full-length bridge beam resting on two GRS abutments at opposite ends subjected to earthquake motions in the longitudinal direction. This study examined the effects of different combinations of reinforcement stiffness J and spacing Sv on the seismic performance of the GRS-IBS. Test results show that reducing the reinforcement spacing was more beneficial to minimize the seismic effect on the GRS abutment as compared to increasing the reinforcement stiffness. The seismic inertial forces acted on the top of two side GRS abutments interacted with each other through the bridge beam, which led to close peak acceleration amplitudes at the locations near the bridge beam. Overall, the GRS-IBS did not experience obvious structure failure and significant displacements during and after shaking. Shaking in the longitudinal direction of the bridge beam increased the vertical stress in the reinforced soil zone. The maximum tensile forces in the upper and lower geogrid layers due to shaking happened under the center of the beam seat and at the abutment facing respectively.

Geosynthetic-reinforced soil structures for railways and roads: development from walls to bridges

The development and construction of various types of geosynthetic-reinforced soil (GRS) structures for railways, roads and others, mainly for railways, for the last 35 years in Japan is described. In the 1980s, GRS retaining wall (RW) with full-height rigid (FHR) facing was developed. The FHR facing is constructed firmly connected to reinforcement layers after the reinforced backfill and subsoil has deformed sufficiently. In the early 1990s, GRS Bridge Abutment supporting one end of a simple girder at the top of the FHR facing was developed. In the early 2000s, GRS Integral Bridge was developed, which structurally integrates both ends of a continuous girder to the top of the FHR facings of a pair of GRS RWs. The total wall length of these GRS structures became about 185 km by June 2019 with no problematic case. The use of FHR facing, the staged construction of FHR facing and the structural integration for GRS Integral Bridge are the three major breakthroughs for the development of these GRS structure technologies.

Numerical parametric study to evaluate the performance of a Geosynthetic Reinforced Soil–Integrated Bridge System (GRS-IBS) under service loading

Abstract This paper presents the evaluation of the performance of the Geosynthetic Reinforced Soil-Integrated Bridge System (GRS-IBS) in terms of lateral facing deformation, strain distribution along geosynthetics, and the location of potential failure zone (locus of maximum strain) subjected to service loading. Simulations were conducted using two-dimensional (2D) PLAXIS 2016 Finite Element (FE) program. The hardening soil model proposed by Schanz et al. (1999) was used to simulate the behavior of the backfill material; the interface between the backfill materials and the reinforcement was simulated using the Mohr-Coulomb frictional model, and the reinforcement and facing block were simulated using the linear elastic model. The numerical model was first verified using results of a field case study conducted at the GRS-IBS of Maree Michel Bridge, Louisiana. A parametric study was then carried out to investigate the effects of abutment height, span length, reinforcement spacing, and reinforcement stiffness on the performance of the GRS-IBS. The results of the FE analyses indicate that the abutment height and span length have significant impact on the maximum strain distribution along the geosynthetic, and the lateral facing displacement. It was noted that the reinforcement stiffness has a significant impact on the GRS-IBS behavior up to a certain point, beyond which the effect tends to decrease contradictory to the reinforcement spacing that has a consistent relationship between the GRS-IBS behavior and the reinforcement spacing. The results also indicate that the reinforcement spacing has greater influence on the lateral facing displacement than the reinforcement stiffness for the same reinforcement strength to spacing ratio (Tf/Sv), mainly due to the composite behavior resulting from closely reinforced soil.

Long-Term Behavior of a Geosynthetic Reinforced Soil Integrated Bridge System in Hawaii

A 109.5-Ft-long Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) in Hawaii was instrumented to measure superstructure strains, vertical pressures below the footing, lateral pressures behind the end wall and modular block facing, and lateral displacements of the facing. Field surveys were also performed to measure the bridge footing settlement. The field data showed that: (1) with time the superstructure compressive concrete strains gradually increased and the end wall lateral pressures gradually decreased, evidence of superstructure concrete creep and shrinkage; (2) three years after construction, the total footing settlement was ≈ 1.2 in.; and (3) the bridge superstructure undergoes daily and seasonal thermal expansion and contraction cycles. Also seasonally, the vertical pressures beneath the footing, lateral pressures behind the end walls, and superstructure strains fluctuate cyclically. The vertical footing pressure closest to the stream experienced the greatest daily pressure fluctuation (≈ 2500−3000 psf), while the one nearest the end wall experienced the least. Based on the results of cyclic triaxial tests on a basalt aggregate similar to the GRS backfill to estimate permanent deformation of the abutment due to daily pressure fluctuations, it was estimated that the permanent strain ≈ 1%, comparable to what was observed in the bridge footing. After three years, the total settlement is about 1.6% of the GRS abutment height; ≈ 0.7% of this is due to the structure dead weight and the remaining 0.9% is due to cyclic loading, consistent with the 1% cyclic strain from laboratory permanent deformation tests.

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

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.

Numerical evaluation of the effect of differential settlement on the performance of GRS-IBS

This paper presents the numerical results of the performance of the Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) due to differential settlement underneath the reinforced soil foundation (RSF), underneath the reinforced zone including the RSF, and underneath the retained soil. The performance was evaluated in terms of reinforcement strain, lateral facing deformation, bump at the approach roadway – bridge slab intersection, and lateral facing pressure. Four different differential settlement values of 50, 100, 150, and 200 mm were selected for this study under three different service loading conditions corresponding to bridge spans of 24.4, 30.5, and 36.6 m. Simulations were conducted using the two-dimensional (2D) PLAXIS 2016 finite element (FE) program. The hardening soil model was used to simulate the backfill material behavior. The interface between the backfill material and the reinforcement was simulated using the Mohr-Coulomb model. The reinforcement and facing block were simulated using the linear elastic model. The results of FE analyses indicate that the differential settlement under the RSF has a high impact on both the strain distribution along the reinforcement and the lateral facing displacement.

Numerical evaluation of the performance of a Geosynthetic Reinforced Soil-Integrated Bridge System (GRS-IBS) under different loading conditions

This paper presents the results of a finite element (FE) numerical analysis that was developed to simulate the fully-instrumented Geosynthetic Reinforced Soil Integrated Bridge System (GRS-IBS) at the Maree Michel Bridge in Louisiana. Four different loading conditions were considered in this paper to evaluate the performance of GRS-IBS abutment due to dead loading, tandem axle truck loading, service loading, and abnormal loading. The two-dimensional FE computer program PLAXIS 2D 2016 was selected to model the GRS-IBS abutment. The hardening soil model proposed by Schanz et al., (1999) that was initially introduced by Duncan and Chang (1970) was used to simulate the granular backfill materials; a linear-elastic model with Mohr-Coulomb frictional criterion was used to simulate the interface between the geosynthetic and backfill material. Both the geosynthetic and the facing block were modeled using linear elastic model. The Mohr-Coulomb constitutive model was used to simulate the foundation soil. The FE numerical results were compared with the field measurements of monitoring program, in which a good agreement was obtained between the FE numerical results and the field measurements. The range of maximum reinforcement strain was between 0.4% and 1.5%, depending on the location of the reinforcement layer and the loading condition. The maximum lateral deformation at the face was between 2 and 9 mm (0.08%–0.4% lateral strain), depending on the loading condition. The maximum settlement of the GRS-IBS under service loading was 10 mm (0.3% vertical strain), which is about two times the field measurements (∼5 mm). This is most probably due to the behavior of over consolidated soil caused by the old bridge. The axial reinforcement force predicted by FHWA (Adams et al., 2011b) design methods were 1.5–2.5 times higher than those predicted by the FE analysis and the field measurements, depending on the loading condition and reinforcement location. However, the interface shear strength between the reinforcement and the backfill materials predicted by Mohr-Coulomb method was very close to those predicted by the FE.

Numerical Investigation of the Geosynthetic Reinforced Soil–Integrated Bridge System under Static Loading

AbstractThis paper presents numerical simulations of the performance of the Geosynthetic Reinforced Soil–Integrated Bridge System (GRS-IBS) under static loading conditions. Simulations were conduct...

Research and construction of geosynthetic-reinforced soil integral bridges

Geosynthetic-reinforced soil (GRS) integral bridge was developed to overcome several inherent serious problems with conventional type bridges comprising a simple-supported girder (or multiple girders) supported via bearings typically by RC abutments retaining unreinforced backfill (and a pier or piers for multiple girders). The problems include: (a) relatively high construction and maintenance costs with relatively long construction time resulting from the use of bearings and massive abutment structures usually supported by piles; (b) bumps immediately behind the abutments; and (c) a relatively low stability of the girders supported by roller bearings and the approach embankment against seismic and tsunami loads. For a GRS integral bridge, a pair of GRS walls (and an intermediate pier or piers if necessary for a long span) are first constructed. After the deformation of the supporting ground and the backfill of the GRS walls has taken place sufficiently, steel-reinforced full-height-rigid (FHR) facings are constructed by casting-in-place concrete on the wall face wrapped-around with the geogrid reinforcement. Finally a continuous girder is constructed with both ends integrated to the top of the FHR facings. The girder is also connected to the top of an intermediate pier, or piers, if constructed. The background and history of the development of GRS integral bridge is described. The first four case histories, one completed in 2012 for a new high-speed train line and the other three completed in 2014 to restore a railway damaged by a great tsunami of the 2011 Great East Japan Earthquake, are reported.

2E12 Design and construction of geosynthetic-reinforced soil structures for Hokkaido Shinkansen(Infrastructure)

The southern part between Shin-Aomori Station (at the north end of Main Island) and Shin-Hakodatehokuto Station (at the south end of Hokkaido Island) of a new high-speed train line called Hokkaido Shinkansen was nearly completed by the end of 2014 and will be opened in 2016. In a range of 37.3 km at the south end of Hokkaido Island, a number of various types of geosynthetic-reinforced soil (GRS) structure were constructed: i.e., 1) GRS retaining walls (RWs) having full-height rigid facing for a length of about 3.5 km, having fully replaced the conventional type RWs; 2) in total 29 GRS bridge abutments, having fully replaced the conventional type bridge abutments; 3) a GRS integral bridge, the world-first one at Kikonai; 4) three GRS box culvert structures integrated to adjacent GRS RWs; and 5) nine GRS protection structures at the tunnel entrance. These GRS structures have been constructed most densely ever for railways, which is definitely so for high speed trains. This paper describes the design and construction of these GRS structures with several lessons learned from this project are summarized.

An analytical model for predicting load–deformation behavior of the FHWA GRS-IBS performance test

The Federal Highway Administration (FHWA) has recently developed a new bridge abutment system, known as Geosynthetic-Reinforced Soil-Integrated Bridge System (GRS-IBS). The term “GRS” refers to a soil mass that is reinforced internally by closely spaced (reinforcement spacing not more than 0·3 m) horizontal layers of geosynthetic sheets. The design protocol of GRS-IBS recommends a “performance test” be conducted to estimate the load–deformation behavior of a GRS-IBS system. The performance test involves a cuboidal block-faced GRS mass that is subjected to increasing axial loads. More than 100 GRS-IBS have been constructed in the US since its introduction in 2011. In light of the rapid development of the new bridge abutment system, an analytical model is developed for predicting the load–deformation behavior of the performance test up to the ultimate load-carrying capacity that is determined from the “W-equation.” This paper presents the analytical model and validation of the analytical model. Validation of the model was accomplished by comparing the analytical results with measured data of four sets of performance tests. The paper also presents a new interpretation of the W-equation, an equation that has been shown to be capable of predicting the ultimate load-carrying capacity of a GRS mass with very good accuracy. The analytical model is seen to give very good predictions of the load–deformation behavior of the performance tests up to the ultimate load-carrying capacity; hence may be used to supplement or replace the FHWA performance test that is rather laborious and time-consuming to conduct.

Design and construction of geosynthetic-reinforced soil structures for Hokkaido high-speed train line

The southern part between Shin-Aomori Station (at the north end of Main Island) and Shin-Hakodate Station (at the south end of Hokkaido Island) of a new high-speed train line called Hokkaido Shinkansen is nearly completed as of the end of 2013 and will be opened in 2015. In a range of 37.3 km at the south end of Hokkaido Island, a number of various types of geosynthetic-reinforced soil (GRS) structure were constructed: i.e., (1) GRS retaining walls (RWs) having full-height rigid facing for a length of about 3.5 km, having fully replaced the conventional type RWs; (2) in total 29 GRS bridge abutments, having fully replaced the conventional type bridge abutments; (3) a GRS integral bridge, the world-first one at Kikonai; (4) three GRS box culvert structures integrated to adjacent GRS RWs; and (5) nine GRS protection structures at the tunnel entrance. These GRS structures are those that have been constructed most densely ever for railways, which is definitely so for high speed trains. In this paper, the design and construction of these GRS structures is described while several lessons learned from this project are summarized.

補強盛土一体橋梁

従来，盛土に隣接する橋梁は橋台と橋桁の組合せで建設されてきたが，盛土の沈下や支承部の維持管理といった問題があった。地盤工学的アプローチとして盛土を補強土として橋台躯体と一体化した補強土橋台が，橋梁工学的アプローチとして橋台と橋桁を一体化したインテグラル橋梁が問題解決策として開発されてきたが，双方とも問題の全てを解決するものではなかった。補強盛土一体橋梁は，補強土橋台とインテグラル橋台を融合させた新形式の橋梁であり，橋台，橋桁，盛土の三者が一体化されている。このため，従来型橋台と比較して橋桁の支持性能，耐震性，維持管理性と経済性に優れている。本稿では補強盛土一体橋梁の原理と施工例について紹介する。

新幹線構造物に用いた補強盛土一体橋梁の動態計測

新幹線構造物に用いた補強盛土一体橋梁の動態計測