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    <title>Transport Research International Documentation (TRID)</title>
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    <copyright>Copyright © 2026. National Academy of Sciences. All rights reserved.</copyright>
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    <managingEditor>tris-trb@nas.edu (Bill McLeod)</managingEditor>
    <webMaster>tris-trb@nas.edu (Bill McLeod)</webMaster>
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      <title>Transport Research International Documentation (TRID)</title>
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    <item>
      <title>Proposed Refinements to Design Procedures for Geosynthetic Reinforced Soil (GRS) Structures in
AASHTO LRFD Bridge Design Specifications</title>
      <link>https://trid.trb.org/View/1598116</link>
      <description><![CDATA[This document is an adaptation of Chapter 8 of the Contractor’s Final Report for NCHRP Project 24‐41, “Defining the Boundary Conditions for Composite Behavior of Geosynthetic Reinforced Soil Structures,” which discusses proposed design refinements for Section 11.10 of the AASHTO LRFD Bridge Design Specifications.  It explores the effect of adopting a closely‐spaced reinforcement layout in geosynthetic‐reinforced soil structures. While research since the early 1980s has identified the beneficial effect of closely‐spaced reinforcement in reinforced soil structures, such improvement in performance is not accounted for in the simplified methodologies established by the American Association of State Highway and Transportation Officials. Considering the effect of closely‐spaced reinforcement may be particularly relevant in critical structures, such as load‐carrying geosynthetic‐reinforced MSE (GMSE) bridge abutments, which eliminate the use of deep foundations to support the bridge loads. In fact, the adoption of closely‐spaced reinforcement was identified as being particularly relevant for these type of structures, leading to specific design guidelines developed by FHWA for structures that became identified as Geosynthetic‐Reinforced Soil Integrated Bridge System, or GRS‐IBS.]]></description>
      <pubDate>Tue, 09 Apr 2019 13:56:33 GMT</pubDate>
      <guid>https://trid.trb.org/View/1598116</guid>
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    <item>
      <title>Innovative Geotechnical Repair Techniques: Effectiveness of Fibre Reinforced Soil</title>
      <link>https://trid.trb.org/View/1570036</link>
      <description><![CDATA[Highways England  commissioned research on innovative geotechnical repair techniques for slopes. Several methods were tested to assess the challenges from environmental constraints, access and utility constraints, and the scale and cost of traffic management.  This report assesses fiber reinforced soil (FRS) as a technique for long-life repair of slopes. The addition of different fibers to improve the physical properties of soil is more widely used in other countries, especially the United States. The use of FRS is reported to have benefits over more common slope repair methods, allowing  the reuse of worn sites by the addition of a small proportion of fiber to the soil fill.]]></description>
      <pubDate>Wed, 27 Feb 2019 09:54:38 GMT</pubDate>
      <guid>https://trid.trb.org/View/1570036</guid>
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    <item>
      <title>Guidelines for the Use of Fiber Reinforced Soil (FRS) in Highway Construction</title>
      <link>https://trid.trb.org/View/1575945</link>
      <description><![CDATA[Fiber Reinforced Soil (FRS) is essentially polypropylene fibers mixed with soil to reinforce the soil mass against shear or tensile failure. This concept has been in use in one form or another throughout history such as clay bricks and mud roofs reinforced with straw in traditional construction in many parts of the world. However, despite its proven record, long history, affordability and ease of construction, this technology has been underutilized, primarily because until relatively recently, extensive laboratory testing, usually in the form of time-consuming and complex triaxial and direct shear tests, was required in order to determine an appropriate application rate. In other words, if an engineer was interested in using FRS, extensive testing was required for each fiber type and range of concentrations of possible interest. However, with significant developments in theoretical models, laboratory testing and field application and verification in the recent years, soil and fiber properties can be used as input values in mathematical models to predict the magnitude of increase in shear strength of the FRS relative to the unreinforced (i.e. raw) soil, and use the resulting data in stability analysis programs to obtain the desired factors of safety in the earthwork project at hand. When the engineer is satisfied with a potential fiber type and application rate, targeted verification tests can be performed as necessary to improve confidence in design. FRS is applicable to a wide range of projects (e.g. retaining walls, slopes, foundations, and pavement subgrades). However, the focus of this study was on its application in repairing shallow slope failures. This report contains a brief review of different slope stabilization techniques beyond soil reinforcement, followed by descriptions of major discrete models developed for FRS, sample preparation and testing procedures in the laboratory, important concepts, and field implementation. Two case studies are also provided together with detailed slope stability calculations, which illustrate alternative methods of using commonly available slope stability analysis programs in combination with FRS data from spreadsheet calculations vs. special programs which can accept fiber properties and application rate as input values in their algorithms. The case study projects included in this report constitute the largest applications of FRS in the United States.]]></description>
      <pubDate>Mon, 31 Dec 2018 09:06:50 GMT</pubDate>
      <guid>https://trid.trb.org/View/1575945</guid>
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    <item>
      <title>Large-scale direct shear and CBR performance of geofibre-reinforced sand</title>
      <link>https://trid.trb.org/View/1516831</link>
      <description><![CDATA[Soils that do not possess desirable engineering characteristics for use for pavement base courses, subbase courses, subgrades, and as a foundation-supporting layer under buildings may be stabilised and improved with geofibre reinforcement. This paper presents results from an extensive and systematic experimental study on the performance of a geofibre-reinforced sand. Large-scale direct shear box and California Bearing Ratio (CBR) performance tests were conducted on samples of poorly graded sand reinforced with fibrillated polypropylene geofibre at gravimetric dosage rates of 0.2%, 0.5%, and 0.8%. The samples were tested in non-submerged and submerged conditions. The variation in shear strength characteristics was evaluated in terms of shear stress–deformation response, peak friction angle, and residual friction angle. The results from the large-scale direct shear tests in both non-submerged and submerged conditions indicate that significant improvement of shear strength may be obtained with a proper dosage of geofibre. The CBR tests of the soil at varying geofibre content show that the inclusion of sufficient geofibre reverses the typical CBR behaviour of unreinforced soil to that indicating more soil resistance, and thus larger CBR values, with increasing depth of penetration.]]></description>
      <pubDate>Thu, 19 Jul 2018 14:45:27 GMT</pubDate>
      <guid>https://trid.trb.org/View/1516831</guid>
    </item>
    <item>
      <title>Installation Summary Report: GRS Instrumentation I-70 over Smith Road</title>
      <link>https://trid.trb.org/View/1479861</link>
      <description><![CDATA[This report presents a summary of the I-70 over Smith Road GRS Instrumentation Project (the project) in Aurora, Colorado. The report summarizes the instruments used, installation means and methods, and a discussion on the web-based data interface. CDOT prepared a preliminary instrumentation design for the project advertisement plans and prior to our task order authorization. Shannon & Wilson provided the design, installation, automatic data acquisition system (ADAS), and the online integrated database management system (webIDMS) for the project. The project included the installation of all instruments, power and communication systems, and connection of temporary and final data logger locations]]></description>
      <pubDate>Tue, 29 Aug 2017 10:09:29 GMT</pubDate>
      <guid>https://trid.trb.org/View/1479861</guid>
    </item>
    <item>
      <title>GRS Wall Performance: Facing Pressure and Deformation</title>
      <link>https://trid.trb.org/View/1479867</link>
      <description><![CDATA[The objective of the study was to validate the performance of blocked-faced Geosynthetic Reinforced Soil (GRS) wall and to validate the Colorado Department of Transportation’s (CDOT) decision to waive the positive block connection for closely-spaced reinforcement, defined in report FHWA-HRT-11-026. Contrary to conventional wisdom, the GRS wall measurements of this study demonstrated that facing pressure decreases as load increases. This counter-intuitive fact is due to the decrease of compaction-induced stress (CIS) with increased load. Therefore, if a GRS wall survives compaction, it survives indefinitely.]]></description>
      <pubDate>Tue, 29 Aug 2017 10:09:08 GMT</pubDate>
      <guid>https://trid.trb.org/View/1479867</guid>
    </item>
    <item>
      <title>Dynamic Characteristics Study of Geosynthetic-Reinforced Soil under Cyclic Loading</title>
      <link>https://trid.trb.org/View/1417194</link>
      <description><![CDATA[The technology of geosynthetic reinforced soil has been widely used in the structural strengthening of highway subgrade. It can improve the bearing and deformation resistance capacity of the subgrade effectively, prolong the service period of the road to ensure the safety and comfort of the vehicle. So far, the quasi-static method to design the geosynthetic reinforced subgrade under the action of traffic load is not perfect enough. The study on dynamic property, design theory and parameters lags far behind the application and improvement of the geosynthetic reinforced soil technology. This paper used the dynamic triaxial test in laboratory by taking different kinds of soil (clay and silt), different confining pressure (50kPa, 100kPa, and 150kPa) and different reinforcement layer (0 layer, 1 layer, and 2 layers) to study the change rule and influence factors of dynamic modulus of elasticity. This study would provide the gist for the improvement of dynamic design theory and parameter choice of geosynthetic reinforced subgrade with the effect of traffic load.]]></description>
      <pubDate>Fri, 23 Sep 2016 11:17:31 GMT</pubDate>
      <guid>https://trid.trb.org/View/1417194</guid>
    </item>
    <item>
      <title>Full-Scale Shake Table Testing to Evaluate Seismic Performance of Reinforced Soil Walls</title>
      <link>https://trid.trb.org/View/1366537</link>
      <description><![CDATA[The objective of this project is to perform numerical studies and use the Large High Performance Outdoor Shake Table (LHPOST) to investigate the dynamic performance of one or two full-scale (7 m) reinforced soil retaining walls constructed using realistic materials and methods.  Considering that these walls will be substantially taller than for any similar previous research (by a factor of 2), a key focus of the proposed research will be on the influence of wall height on overall system response (i.e., stability/deformation) and the distribution of dynamic tensile forces (i.e., seismic demand) in the soil reinforcement.  Other focus areas will include dynamic earth pressure on facing elements, effects of dynamic loading on soil-reinforcement stress transfer mechanisms, and permanent deformations after dynamic loading. The tests will be conducted using a unique large soil confinement box (LSCB) that is currently under construction as part of a recently funded National Science Foundation (NSF) grant. The scale of these tests will permit wall construction using realistic soil types, compaction methods, and structural elements.  The box will also have a unique design that permits different boundary conditions at the rear of the soil mass, including a water-filled bladder or geofoam layer.]]></description>
      <pubDate>Sat, 22 Aug 2015 01:01:02 GMT</pubDate>
      <guid>https://trid.trb.org/View/1366537</guid>
    </item>
    <item>
      <title>Influence of Leveling Pad Interface Properties on Soil Reinforcement Loads for Walls on Rigid Foundations</title>
      <link>https://trid.trb.org/View/1310161</link>
      <description><![CDATA[A verified numerical Fast Lagrangian Analysis of Continua (FLAC) code is used to investigate the influence of concrete- and granular-block interface properties on reinforcement loads in polyester geogrid-reinforced soil (modular) block walls seated on a rigid foundation. A nonlinear interface model simulating interfaces between concrete blocks and concrete or granular soil leveling pads calibrated against laboratory direct shear tests is implemented within the FLAC code. The code is then used to simulate 3.6-, 6- and 9-m-high block walls constructed in stages. The numerical results show that the increase in wall height during wall construction for the same wall increases the interface tangent stiffness. However, the concrete pad results in higher interface tangent stiffness compared to the granular soil pad case when other conditions are equal. For 3.6-m-high walls, the load carried by the toe when using the granular soil leveling pad is 14% less than for the concrete pad case. For 9-m-high walls, the difference in load carried by the toe for the two different leveling pads is less than 10%. The predicted reinforcement loads at the same elevation over the bottom 1/3 of the wall height for the concrete pad case are smaller than those for the granular soil pad case, but are similar over the remaining height of the wall. The results also show that the predicted reinforcement loads using the K-stiffness Method capture the trend in numerical results for the two leveling pad conditions, but are conservative (i.e. safer for design), particularly for the higher walls.]]></description>
      <pubDate>Mon, 30 Jun 2014 09:44:25 GMT</pubDate>
      <guid>https://trid.trb.org/View/1310161</guid>
    </item>
    <item>
      <title>Load-Carrying Capacity and Required Reinforcement Strength of Closely Spaced Soil-Geosynthetic Composites</title>
      <link>https://trid.trb.org/View/1258977</link>
      <description><![CDATA[In current design methods for reinforced soil walls, it has been tacitly assumed that reinforcement strength and reinforcement spacing play an equal role. This fundamental design assumption has led to the use of larger reinforcement spacing (0.3–1.0 m) in conjunction with stronger reinforcement to reduce construction time. Recent studies, however, have clearly indicated that the role of reinforcement spacing is much more significant than that of reinforcement strength. With closely spaced (reinforcement spacing ≤0.3 m) reinforcement, the beneficial effects of geosynthetic inclusion is significantly enhanced, and the load-deformation behavior can be characterized as that of a composite material. A reinforced soil mass with closely spaced geosynthetic reinforcement is referred to as geosynthetic-reinforced soil (GRS). In this study, an analytical model is developed for predicting the ultimate load-carrying capacity and required reinforcement strength of a GRS mass. The model was developed based on a semiempirical equation that reflects the relative roles of reinforcement spacing and reinforcement strength in a GRS mass. Using measured data from field-scale experiments available to date, it is shown that the analytical model is capable of predicting the ultimate load-carrying capacity and required reinforcement strength of a GRS mass with good accuracy.]]></description>
      <pubDate>Tue, 03 Sep 2013 12:29:52 GMT</pubDate>
      <guid>https://trid.trb.org/View/1258977</guid>
    </item>
    <item>
      <title>Composite Behavior of Geosynthetic Reinforced Soil Mass</title>
      <link>https://trid.trb.org/View/1259931</link>
      <description><![CDATA[This study investigated the composite behavior of a geosynthetic reinforced soil (GRS) mass. Many studies have been conducted on the behavior of GRS structures; however, the interactive behavior between the soil and geosynthetic reinforcement in a GRS mass has not been fully elucidated. Current design methods consider the reinforcement in a GRS structure as tiebacks and adopt a design concept that the reinforcement strength and reinforcement spacing produce the same effects on the performance of a GRS structure. This has encouraged designers to use stronger reinforcement at a larger spacing to reduce time and effort in construction. A series of large-size generic soil geosynthetic composite (GSGC) tests were designed and conducted to examine the behavior of a GRS mass under well-controlled conditions. The tests clearly demonstrated that reinforcement spacing has a much stronger impact than reinforcement strength on the performance of the GRS mass. An analytical model was established to describe the relative contribution of reinforcement strength and reinforcement spacing. Based on the analytical model, equations were developed to calculate the apparent cohesion of a GRS composite, the ultimate load-carrying capacity of a GRS mass, and the required tensile strength of reinforcement for a prescribed value of spacing. The equations were verified using measured data from the GSGC tests and measured data from large-size experiments by other researchers, as well as by results of the finite element (FE) method of analysis. Due to the popularity of GRS walls with modular block facing, an analytical procedure was developed for predicting the walls’ lateral movement. This procedure also allows the required tensile strength of the reinforcement to be determined by simple calculations. In addition, compaction-induced stresses, which have usually been ignored in design and analysis of GRS structures, were investigated. An analytical model for estimating compaction-induced stresses in a GRS mass was proposed. Preliminary verification of the model was made by using results from the GSGC tests and FE analysis. The dilative behavior of a GRS composite was also examined. The presence of geosynthetic reinforcement has a tendency to suppress dilation of the surrounding soil and reduce the angle of dilation of the soil mass. The dilative behavior offers a new explanation of the reinforcing mechanism, and the angle of dilation may be used to reflect the degree of reinforcing of a GRS mass.]]></description>
      <pubDate>Tue, 03 Sep 2013 12:25:06 GMT</pubDate>
      <guid>https://trid.trb.org/View/1259931</guid>
    </item>
    <item>
      <title>Recognizing the Benefits of GRS Bridge-building Technology</title>
      <link>https://trid.trb.org/View/1213825</link>
      <description><![CDATA[This article discusses how the Federal Highway Administration (FHWA) and the local officials in Defiance County, Ohio built the first geosynthetic reinforced soil (GRS) integrated bridge more than seven years ago.  The article shows how county engineers throughout the country are beginning to recognize the benefits of using GRS technology.  GRS technology uses alternating layers of compacted fill and sheets of geotextiles in order to provide support for integrated bridge systems. The article discusses the history and benefits of using GRS technology in bridge construction.]]></description>
      <pubDate>Mon, 17 Sep 2012 09:23:59 GMT</pubDate>
      <guid>https://trid.trb.org/View/1213825</guid>
    </item>
    <item>
      <title>Geosynthetic Reinforced Soil for Low-Volume Bridge Abutments</title>
      <link>https://trid.trb.org/View/1136638</link>
      <description><![CDATA[This report presents a review of literature on geosynthetic reinforced soil (GRS) bridge abutments, and test results and analysis from two field demonstration projects (Bridge 1 and Bridge 2) conducted in Buchanan County, Iowa, to evaluate the feasibility and cost effectiveness of the use of GRS bridge abutments on low-volume roads (LVRs). The two projects included GRS abutment substructures and railroad flat car (RRFC) bridge superstructures. The construction costs varied from $43k to $49k, which was about 50 to 60% lower than the expected costs for building a conventional bridge. Settlement monitoring at both bridges indicated maximum settlements ≤1 in. and differential settlements ≤ 0.2 in transversely at each abutment, during the monitoring phase. Laboratory testing on GRS fill material, field testing, and in ground instrumentation, abutment settlement monitoring, and bridge live load (LL) testing were conducted on Bridge 2. Laboratory test results indicated that shear strength parameters and permanent deformation behavior of granular fill material improved when reinforced with geosynthetic, due to lateral restraint effect at the soil-geosynthetic interface. Bridge LL testing under static loads indicated maximum deflections close to 0.9 in and non-uniform deflections transversely across the bridge due to poor load transfer between RRFCs. The ratio of horizontal to vertical stresses in the GRS fill was low (< 0.25), indicating low lateral stress on the soil surrounding GRS fill material. Bearing capacity analysis at Bridge 2 indicated lower than recommended factor of safety (FS) values due to low ultimate reinforcement strength of the geosynthetic material used in this study and a relatively weak underlying foundation layer. Global stability analysis of the GRS abutment structure revealed a lower FS than recommended against sliding failure along the interface of the GRS fill material and the underlying weak foundation layer. Design and construction recommendations to help improve the stability and performance of the GRS abutment structures on future projects, and recommendations for future research are provided in this report.]]></description>
      <pubDate>Wed, 16 May 2012 15:06:53 GMT</pubDate>
      <guid>https://trid.trb.org/View/1136638</guid>
    </item>
    <item>
      <title>Use of MSE Technology to Stabilize Highway Embankments and Slopes in Oklahoma</title>
      <link>https://trid.trb.org/View/1104162</link>
      <description><![CDATA[Departments of transportation across the U.S. are faced with the persistent problem of landslides and slope failures along roads and highways.  Repairs and maintenance work associated with these failures cost these agencies millions of dollars annually.  Over the past few decades, Mechanically Stabilized Earth (MSE) technology has been successfully used as a cost-effective solution for the construction and repair of slopes and retaining structures in transportation applications.  Significant cost-savings in the re-construction and repair of highway slopes and embankments could be achieved by using locally available soils and reinforcing them with geosynthetics.  However, locally available soils in many locations are of marginal quality and their shear strength and interaction with the geosynthetic reinforcement can be significantly dependent on their moisture content.  As a result, the influence of soil moisture content and suction on the soil-reinforcement interaction needs to be properly accounted for in the design of reinforced soil slopes and embankments.  Provisions related to the influence of soil suction on the shear strength of soil-reinforcement interfaces are currently lacking in the existing design guidelines for these structures.  In this study, a moisture reduction factor was developed for the pullout resistance of a geotextile reinforcement material in an Oklahoma soil (termed here as Chickasha soil) that could be used for the design of reinforced soil structures with marginal soils.]]></description>
      <pubDate>Tue, 21 Jun 2011 09:28:56 GMT</pubDate>
      <guid>https://trid.trb.org/View/1104162</guid>
    </item>
    <item>
      <title>Compressive Performance of Geogrid-Reinforced Granular Soil</title>
      <link>https://trid.trb.org/View/1089567</link>
      <description><![CDATA[A series of unconfined compression tests were conducted in laboratory to investigate the compressive behavior of geogrid-reinforced granular soil. Samples, each varying either in the reinforcement spacing (S) or the relative compaction of the granular soil (K), were prepared with S of 2.5 cm, 3 cm, 3.75 cm, 5 cm or 7.5 cm and K of 88 %, 92 %, or 96 % respectively. Based on a detail analysis of the effect of S and K on the compressive stress-strain response, the following conclusions were obtained: (1) the compressive strength increased either with the increase of K or with the decrease of S, but there was an optimum match of K with S, which leading an expected reinforcement benefit (enough compressive strength at a permissible strain) economically; (2) geogrid-reinforced granular soil had a higher compressive strength but a much more lower failure strain compared to geotextile-reinforced granular soil.]]></description>
      <pubDate>Wed, 16 Feb 2011 13:41:57 GMT</pubDate>
      <guid>https://trid.trb.org/View/1089567</guid>
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