Geosynthetic Reinforcement Research Articles

Discussion of “Effects of Traffic Loading on Seasonal Temperature Change-Induced Problems for Integral Bridge Approaches and Mitigation with Geosynthetic Reinforcement”

Discussion of “Effects of Traffic Loading on Seasonal Temperature Change-Induced Problems for Integral Bridge Approaches and Mitigation with Geosynthetic Reinforcement”

Effect of Testing Mechanisms on the Load-Strain-Time Behavior of Geosynthetic Reinforcements

Abstract This study compares how geosynthetics behave under load, under strain, and over time when subjected to confined tensile tests in soil, employing two commonly used mechanisms in research. One test type simulates a reinforced layer, where tensile loads are indirectly applied to the geosynthetic via stresses transferred from the soil. In contrast, the other test applies tensile loads directly to the geosynthetic material using clamps while under soil confinement. The objective is to elucidate how these testing mechanisms might yield differing in-soil tensile characteristics for different geosynthetics. The study involved conducting load-strain-time tests on samples of nonwoven and woven geotextiles, as well as a geogrid, under varying sustained loads over a 120-h period within a sand clay soil providing soil confinement to geosynthetics at different surcharge levels. The results suggest that soil confinement plays a significant role in shaping the load-strain-time behavior of geosynthetics. Furthermore, it was noted that the impact of testing mechanisms on this behavior is contingent upon the type and stiffness of the geosynthetics, as well as their interaction with the confining soil. In general, in-soil tests in which tensile loads are mobilized by geosynthetics and transferred from the soil provide more confident results for better simulating operation conditions. Tests that directly apply tensile loads to the geosynthetic while maintaining stationary soil confinement may yield misleading results, especially for geosynthetics that have poor interaction with the soil.

Non-Destructive Methods for Assessing the Condition of Reinforcement Materials in Soil

A reinforced earth wall is a structure in which reinforcement materials are placed in an embankment to build a vertical or nearly vertical wall surface. Such walls have been widely used in roads and in developed land since around 1960. Reinforcement materials have a set service life of 100 years and fall into two types: steel and geosynthetics. To ensure long-term durability, steel reinforcement materials are plated, while geosynthetics are designed with a limit strength designed to resist fracture for 100 years under the conditions of a given load placed on the reinforcement materials. However, owing to the difficulty of assessing the condition of reinforcement materials in soil, this paper proposes solutions based on non-destructive methods. Specifically, it proposes a method of assessing the amount of strain through an embedded optical fiber in the case of geosynthetic reinforcement materials, or magnetic surveying to investigate the degree of corrosion in the case of steel reinforcement materials. This paper demonstrates that it is possible to non-destructively assess the state of either type of reinforcement material.

Discrete element analysis of geosynthetic-reinforced pile-supported embankments

A discrete element trapdoor model was established using the MatDEM software, and the effects of different embankment and reinforcement heights on the soil arching effect of embankments under reinforced conditions were investigated by introducing a biaxial geogrid. The outcomes demonstrated that the inclusion of a geosynthetic reinforcement could enhance the load transfer efficacy of the embankment and thereby reduce the differential settlement of the embankment surface. The differential settlement could be reduced by approximately 50 % when the reinforcement height and the pile cap were close. The inclusion of the geosynthetic reinforcement helped reduce the development of the slip surface within the embankment above the reinforcement and prevented the vertical slip surface from continuing to move upwards, thus ensuring that the soil arching effect did not degrade too quickly and continued to play a role. In the case of a low embankment reinforcement, the soil arching effect was largely nonfunctional because of the rapid development of the vertical slip surface, and the load on the embankment in the soft soil was mainly transferred to the piles through the tensioned membrane effect of the geosynthetic reinforcement. For a high embankment with a low reinforcement height, the soil arch structure of the embankment was well maintained, the soil arching effect did not degrade, and the load on the embankment in the upper part of the soft soil was transferred to the piles via the soil arching effect along with the tensioned membrane effect. In the case of a high embankment with a high reinforcement, the reinforcement blocked the vertical slip surface only for the soil above the reinforcement height, whereas the vertical slip surface below the reinforcement height developed in line with that of the same height, when the tensioned membrane effect and soil arching effect worked together in the embankment above the reinforcement height, and the soil arching effect below the reinforcement height degraded and hardly played a role.

Evaluating the mechanisms and performance of Geosynthetic-Reinforced Load Transfer Platform of pile-supported embankments design methods

This study evaluates the existing design methods of Geosynthetic-Reinforced Load Transfer Platform for Pile-Supported Embankments (GLTP-PSE) through comprehensive 3D Finite Element (FE) analyses. It scrutinizes the assumed arching mechanisms, methodologies, design criteria (arching height, maximum strain, differential settlement, and T in geosynthetics), and overall performance of these methods. The 3D FE analysis results and measurements from two case studies were compared with six established GLTP-PSE design methods based on the four design criteria. Key findings include the identification of a progressive concentrated ellipsoid as the developed soil arching formation, with arching height dependent on the embankment equivalent height (including embankment and traffic load), pile spacing, maximum strain along the geosynthetics, and the number of geosynthetic layers. The load distribution on geosynthetic reinforcement was observed to align more closely with a non-linear inverse triangle. These insights led to recommendations for updating existing design methods, enhancing the accuracy and reliability of GLTP-PSE designs. The study's outcomes contribute significantly to advancing and refining GLTP-PSE design practices by providing a deeper understanding of soil arching mechanisms and the performance of geosynthetic reinforcements.

Large-scale direct shear testing for assessing interfacial parameters of natural and recycled sand with geosynthetic reinforcements

The demand for infrastructure projects is being driven by urbanization, which led to scarcity of natural sand (NS), which prompts exploration of alternative sustainable construction materials due to environmental concerns. Recycled sand (RS), processed from construction and demolition waste (C&DW), is an alternative material in infrastructure applications. Investigating interfacial shear behaviour between geosynthetic reinforcements with RS as a sustainable alternative material is crucial for infrastructure projects. This study presents the comprehensive large-scale direct shear testing (LSDST) on RS, NS, and its interfaces with ten types of geosynthetic reinforcements (i.e., polypropylene geogrids (GRD1 – GRD3), polyester geogrids (GRD4 – GRD6), and geotextiles (GT1 – GT4). LSDST were carried out using self-fabricated direct shear testing equipment of size equal to 500 mm x 500 mm x 300 mm (L x B x H). The findings indicate that the RS and NS exhibit similar shear strength parameters, sand-GRD interface demonstrates greater resistance compared to the sand-GT interface. RS and NS-GRD4 - GRD6 interfaces with transverse ribs and rough texture and NS-GRD1 interface with triangular apertures, exhibit significant shear strength parameters than the unstabilized case due to the mobilization of passive thrust. Interfacial shear coefficients for NS and RS range from 0.94 – 1.27 and 0.80 – 1.15 for GRD interfaces, and 0.89 – 1.06 and 0.86 – 0.99 for GT interfaces, respectively. Therefore, the RS can be a sustainable alternative for NS.

Performance evaluation of marginal materials in geosynthetic reinforced base layers

The high-altitude regions are prone to natural disasters such as landslides, and tunnelling that generate substantial amounts of debris. Utilising these waste (marginal) materials in the pavement sector offers a viable solution. This study aims to stabilise tunnel muck, landslide debris, and Reclaimed Asphalt Pavement using geosynthetics (geogrid, geocell, double geogrid, and geogrid + geocell) for the base course. Cyclic Plate Load tests were performed on pavement prototypes built with available marginal materials and conventional GSB as the base/subbase course, with Black cotton and silty soil subgrades. The results indicated that geosynthetic reinforcement significantly improved the performance of marginal materials by lowering permanent deformation and increasing design life. The pavement prototypes reinforced with double geogrid and geogrid + geocell indicated rutting performance equivalent to conventional GSB for specific combinations. Additionally, incorporating geosynthetics in pavement layers increased the structural strength of the base layers by a layer coefficient ratio factor ranging from 1.1 to 2.5.

Coupled influence of geosynthetic reinforcement and column configuration on failure dynamics in deep mixed columns under embankment loading

Coupled influence of geosynthetic reinforcement and column configuration on failure dynamics in deep mixed columns under embankment loading

Seismic Performance Assessment for Serviceability of Geosynthetic Reinforced Embankments

Embankments in the field of civil engineering were historically not given much attention in terms of their ability to withstand seismic activity, as they were considered to be non-critical structures. However, in recent years, the seismic stability of embankments has gained increasing importance in the field of geotechnical engineering. This increased significance is due to the need to quickly restore functional infrastructure after earthquakes. The occurrence of lateral spreading, resulting from foundation liquefaction, is the primary factor leading to embankment distress in geotechnical engineering during seismic events. To address this issue, this study presents a novel approach that employs geosynthetic basal reinforcement. The research paper presents a technique that uses geosynthetic basal reinforcement to manage the lateral spreading of embankments both pre- and post-earthquakes, guaranteeing their ongoing effectiveness. The proposed approach utilizes a pseudo-static limit equilibrium method for determining the tensile load produced in the basal reinforcement. The serviceability criteria establish the maximum strain permitted in the basal reinforcement by imposing a restriction on the horizontal movement of the embankment toe. By taking into account the tensile load of the reinforcement and the maximum allowable strain, it is feasible to establish an appropriate geosynthetic reinforcement that considers various factors including tensile strength, strain, design life, installation, and durability impacts.

A Study on Geosynthetic reinforcement of soil using Plastic Chips and Bottom Ash

A Study on Geosynthetic reinforcement of soil using Plastic Chips and Bottom Ash

A REVIEW ON Geosynthetic reinforcement of soil using Plastic Chips and Bottom Ash

A REVIEW ON Geosynthetic reinforcement of soil using Plastic Chips and Bottom Ash

Enhancing clay soil stability in seasonal freezing areas through waste cherry marble powder and geotextile reinforcement

In this study, the mechanical and durability performance of clay soils reinforced with different proportions of Cherry Marble Powder (CMP) and non-woven geotextile configurations, both independently and in combination, is investigated in detail at both the macro and micro levels. The effectiveness of reinforcement in the stabilization of clay soils in cold climates has been evaluated by means of Gray Correlation Analysis (GCA). The results show that as the CMP ratio and the number of geotextiles increase, the peak strength of the soil increases, with higher CMP levels showing perfect plastic behavior and more geotextiles showing linear strain hardening, particularly in combination. Substantial strength reductions post-7th cycle ranged between 91.09 % and 103.38 % for 12 % CMP and 219.83 % and 270.42 % for three-layered geotextile groups. Cohesion increased by 59.76 % and 179.41 %, while the internal friction angles remained stable and decreased after F-T cycles, except with additives. Failure modes shifted with CMP content, F-T cycles and confining pressure. The transition was from strain hardening to strain softening, with increased shear fracture planes and brittleness. The energy absorption capacity (EAC) increased with the CMP ratio, with the geosynthetic reinforcement increasing the EAC by a factor of 1.5 before and after the F-T cycles. The combined use of CMP and geotextiles in soil stabilization improved the engineering properties in areas of frost, with the optimum gradation being three layers of geotextile and a CMP ratio of 12 %, which effectively mitigated the effects of the maximum F-T cycle.

Experimental and theoretical studies on deformation characteristics of Geosynthetic-Reinforced Soil (GRS) abutments induced by vertical loads

This study conducted five centrifuge model tests to investigate the deformation characteristics of the Geosynthetics Reinforced Soil (GRS) abutments under vertical loads, considering the setback distance ab and beam seat width B as two major influencing factors. Test results show that a linear correlation existed between the maximum lateral facing displacements DL and the maximum settlements at the top of the GRS abutments Dv. The ab and the B had different effects on the deformation characteristics of the GRS abutments as well as the relationship between the DL and the Dv. The total volumetric strains of the GRS abutments were smaller than 0.3% for all the cases investigated in this study, indicating that it was reasonable to use the assumption of zero-volume change for the deformation calculation of the GRS abutments. This study proposed an improved semi-empirical method to describe the relationship between the DL and the Dv. Centrifuge test results and data collected from the literature were used to validate the improved method. It was concluded that the improved method had the advantage of considering the effects of the ab and the B separately and therefore significantly improved the prediction accuracy of the deformations of the GRS abutments.

Parametric Analysis for a Low-Volume Concrete Road with Reinforced Subgrade Subjected to Swelling Pressure

Abstract This paper presents the parametric analysis of a combined system of a low-volume concrete pavement, base layer and reinforced expansive soil, subjected to the stresses due to wheel loading and swelling of the soil. A soil-structure Interaction model is considered for the analysis, in which the pavement and the reinforcement are idealized as a finite beam, with plane-strain conditions, whereas a base layer and the expansive soil are modelled as Winkler Springs of different stiffnesses. During the analysis, it was taken into account that the geosynthetic reinforcement, which could be in the form of a geogrid, geocell, or a combination of both, possesses bending stiffness and is placed at the interface between the base layer and the expansive subgrade. The reinforcement layer is subjected to stresses due to wheel load, self-weight of pavement slab and surcharge load of the base layer at the top and the swelling pressure from the subgrade at its bottom. The governing differential equations for the flexural response of the model are derived and a closed-form solution is presented in a non-dimensional form. The outcomes of the parametric analysis highlight that the flexural response of the pavement is predominantly affected by the relative stiffness of the base layer and the expansive subgrade. In contrast, the relative flexural rigidity of the upper and lower beams has a comparatively minor impact on the model’s response. Additionally, parameters like the depth of placement of the lower beam, unit weight of the upper soil layer, and the self-weight of the upper beam also contribute to influencing the response of the pavement model. The study suggests that, while designing for the concrete pavement, opting for an increase in the modulus of subgrade of expansive soil may be a preferable choice over reinforcing the foundation of the pavement.

Influences of number of geosynthetic reinforcement layers on soil arching under cyclic loading

Geosynthetic-reinforced pile supported (GRPS) embankments have been widely used in highways and railways on soft subsoil. During the operation period, these embankments are often subjected to cyclic loading, such as traffic loading. Considering that soil arching is a key load transfer mechanism in these embankments, the development of soil arching under cyclic loading is vital important to operational safety of these embankments. Conventional trapdoor system cannot represent actual conditions of soil arching in GRPS embankments because it have a forcibly-moved trapdoor and cannot simulate load-induced subsoil settlement. Hence, this paper used a self-moving trapdoor supported by compression springs that moved up and down dependent on its overburden pressure. To investigate influences of number of geosynthetic reinforcement layers on soil arching under cyclic loading, two self-moving trapdoor tests were conducted, including a single layer and two layers, where the total reinforcement stiffness were approximately same. The trapdoor test results show that the inclusion of two reinforcement layers with a fill layer of a certain height in between reduced surface settlement of the fill and tensile forces of reinforcement, as compared with a single reinforcement layer. It also enhanced soil arching effect and improved the stability of soil arching under cyclic loading.

Approaching road design from a sustainability perspective

The construction industry began emphasizing the three major pillars of sustainable development after the 1987 Brundtland Report. Sustainable design methodologies focus on life-cycle costs and the associated impacts of construction, operation, and maintenance. Maintaining road infrastructure accounts for a significant portion of the development budget owing to recurring costs, construction, and material extraction, while also resulting in other difficulties for the society. Poor road quality induce increased cost of living and degraded quality of life. Owing to front-end costs, road owners are typically motivated to pursue designs focused on the project’s initial cost. This is primarily attributable to a lack of understanding of sustainable development parameters. Life cycle cost attempts to quantify the environmental costs of sustainable construction. However, societal factors have been generally ignored. Currently, road section design is open to the designers’ choice of conventional unreinforced sections or a wide variety of planar and three-dimensional geosynthetic reinforcements. This study defined quantitative and scaled qualitative measures for designing road infrastructure using a sustainable approach. The methodology was explained using a full-scale real-life road project.

Numerical modelling of reinforced fill over a void considering rate-dependent stiffness of the reinforcement

The problem of a reinforced fill over a void has been the subject of much research in the geosynthetics literature. Previous studies have mainly focused on finding closed-form solutions to predict the tensile loads and strains in the reinforcement layer once a void develops below the fill. In this paper, a 2D finite difference (FLAC) model that implements the hyperbolic isochronous load-strain model for the reinforcement by Bathurst and Naftchali (2021) is used to investigate the influence of the rate-dependent properties of polymeric geosynthetic reinforcement materials on reinforcement tensile strains and load, and overall system performance including vertical deformation at the reinforcement elevation and at the fill surface. The paper also investigates the influence of fill soil properties and constitutive model type, foundation condition, void geometry and fill height on system performance. The results of numerical modelling are compared to predictions made using the closed-form solution of Giroud et al. (1990) and in the BSI 8006-1 (2010) design code. The results of numerical modelling demonstrate that the choice of fill height to void width and the stiffness of the rate-dependent geosynthetic reinforcement layer are important to ensure that the maximum reinforcement strain, allowable strength and fill surface settlement criteria are not exceeded.

The effect of geosynthetic reinforcement on the load transfer mechanism of pile-supported low embankments subject to cyclic traffic loading

Pile-supported embankments are commonly employed for highways in soft soil areas. Extensive studies have been conducted on high embankments under static loading. However, low embankments with lower costs and carbon footprint have not yet been thoroughly studied. This study aims to investigate the performance of pile-supported low embankments under cyclic traffic loading by carrying out two large-scale model tests. The soft soil was constructed using Kaolin clay, and the cyclic traffic loading was simulated using a localized semi-sinusoidal function. The effect of geosynthetic reinforcement on the load transfer mechanism of pile-supported low embankments was investigated by comparing the measured data from unreinforced and reinforced cases. Test results show that geosynthetic reinforcement reduces settlement and leads to faster stabilization of settlement in low embankments. Pile-supported low embankments experience a rapid decrease followed by a stabilization in pile efficacy with increased cyclic loading, and geosynthetic reinforcement increase the pile efficacy and facilitate quicker stabilization. Geosynthetic reinforcement enhances the transfer of static and dynamic stresses to piles, resulting in less stress degradation under cyclic loading. Based on experimental results, pile-supported embankments should account for the adverse effects of cyclic loading, even if they are classified as high embankments according to existing analytical models.

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.

Analysis of deformations of road embankments founded on displacement columns improving soft subsoil

Drilled displacement columns, constructed in the form of unreinforced or reinforced concrete elements, are currently a very commonly used method of improving soft subsoil, creating an alternative to more expensive pile foundations. A frequently used solution for improving soft soils of road or railway embankments is to design a regular pattern of columns of relatively small diameter. Columns along the perimeter of the improved area are reinforced with rigid steel profiles, while the internal ones are made as concrete elements. Column heads are usually covered with a load transfer platform (layer of compacted granular fill) which is additionally reinforced with geosynthetics. The application of soil improvement with displacement columns is not always successful. It is due to the errors and shortcomings occurring at the design stage, including simplifications in modelling, to construction faults, which may include insufficient experience of contractors and/or improper supervision. Referring to the real object that failed, the article provides the results of numerical parametric analyses taking into account the influence of the key design parameters such as: the stiffness of the load transfer layers, the amount and stiffness of the geosynthetic reinforcement as well as the column spacing. The article presents comparisons of numerical results obtained with the finite element analyses for various approaches to geometry modelling (axisymmetric, 2D and 3D). The simulations indicate that the use of the axisymmetric model of a single column in routine design may lead to the deformations exceeding the serviceability limit states.