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To examine the hydro-mechanical behavior of Geosynthetic Reinforced Soil Walls (GRSW) backfilled with locally available marginal lateritic soils, physical model tests were conducted during construction, surcharge loading, and rainfall infiltration. Various reinforcements were tested, including a conventional geogrid (GG) and two types of composite geosynthetic reinforcements (CGR) with equivalent stiffness but different configurations. The results showed that suction was maintained throughout surcharging, but during rainfall infiltration, the GG model lost suction after 12,240 min, while both CGRs retained it. Strain evaluations indicated that all reinforcements remained within serviceability limits during surcharging, but the GG model exceeded these limits during rainfall, while the CGRs stayed within acceptable limits with minimal strain increases. Additionally, the GG model showed a 61% increase in facing deformation during rainfall, exceeding serviceability limits, whereas the CGRs remained within permissible limits. The study emphasizes the importance of cautious use of marginal soils in backfill applications. These soils can still be suitable for GRSW when reinforced with composite geosynthetics, especially CGR made of polyester geogrids with non-woven geotextile bonded longitudinally to the polyester strips. This configuration demonstrated superior performance by reducing facing deformation through better drainage and improved soil-reinforcement interaction. • Instrumented model tests on Composite-Geosynthetic-Reinforced Soil Walls with unsaturated marginal lateritic backfills. • Application of composite geosynthetic reinforcements (CGR) in-lieu of conventional geogrids (GG). • Influence of configuration of CGR on the performance of GRS wall. • Wall deformation and reinforcement strains during construction of wall, surcharge loading and rainfall infiltration. • Impact of suction loss due to rainfall-induced wetting on the behaviour of GRS wall through instrumented model tests. [Display omitted] [ABSTRACT FROM AUTHOR]

Although Novel Polymeric Alloy (NPA) geocells have been applied to stabilize road bases against the freeze-thaw (F-T) damage in practice, the relevant research lags the application. A scarcity of research has been reported to comprehensively evaluate the benefits of geocell stabilization in enhancing the F-T performance of bases. This study aims to investigate quantitatively the F-T performance of geocell-stabilized bases, focusing on two influencing factors-i.e., water supply and degree of compaction in the bases. A series of model-scale experimental tests (19 tests) was conducted using an upgraded customized apparatus. The results showed that the inclusion of geocells was beneficial for reducing frost heave and thaw settlement as well as mechanical properties (i.e., stiffness and ultimate bearing capacity) of road bases. The benefit of geocells was more remarkable for the well compacted bases than for the poorly compacted bases. The benefit was more pronounced in the open system than in the closed system. • Model tests were done to study - F-T responses of geocell-stabilized bases considering effect of water supply and compaction. • The use of geocells increased the stiffness of bases by approximately 40%–90% after five F-T cycles. • The use of geocells increased the ultimate bearing pressure of bases by approximately 80%–110% after five F-T cycles. [ABSTRACT FROM AUTHOR]

The smooth surface texture of the commercially available geogrids limits the shear strength mobilization at the interfaces. This study presents the design, manufacturing, and interface performance evaluation of innovative textured geogrids. Geogrids with square, triangular, and hexagonal apertures with and without inherent surface texture were manufactured through additive manufacturing (3D printing) technique, using PLA (Poly Lactic Acid) filament. The texture includes elevated pins of 3 mm height at the junctions and inherent diamond pattern of 1 mm height on the ribs. The individual and combined effects of surface texture and aperture shape on the stress–displacement relationship, dilation angle, and the thickness of shear zone are quantified using large-scale direct shear tests and Particle Image Velocimetry (PIV) analysis. Results showed that the textured geogrid with hexagonal aperture has exhibited the maximum interface coefficient of 0.96 with sand followed by the geogrids with triangular and square apertures. Irrespective of the aperture shape, provision of the surface texture resulted in an overall increase of interface shear strength by more than 13%. Further, PIV analysis revealed that the shear zone is 25% thicker for textured geogrids of different aperture shapes, suggesting higher interlocking and passive resistance offered by their textured surfaces. • Concept, design, and manufacturing of innovative textured geogrids are described. • Performance of textured geogrids are studied in tension and interface shear. • Influence of surface texture configuration and aperture shape on tensile and interface shear strength is studied. • Contribution of surface texture on shear strength of geogrid-sand interfaces is quantified. • PIV analysis is performed to visualize the micro scale internal processes during interface shear tests. • The efficient configuration of surface texture and aperture shape for deriving maximum benefits from geogrid are suggested. [ABSTRACT FROM AUTHOR]

Geogrid-reinforced calcareous sand (GRCS) is an attractive alternative to enhance the bearing capacity and stability of geotechnical structures in island and coastal areas. Understanding the geogrid–particle interaction and shear mechanical behavior is the current challenge. This work investigated the shear mechanical behavior of the GRCS under the influence of inclination angle, stress level, geogrid type, and the number of geogrids employing large-scale direct shear tests. The results revealed that the shear strength of the three-layer inclined reinforcement increased by an average of 81% and 59% compared to the unreinforced and horizontally reinforced conditions, respectively. The internal friction angle and the pseudo cohesion at the shear plane were particularly sensitive to the inclined reinforcement condition, with maximum values of 54.7° and 55 kPa, respectively. The increased inclination angle and geogrids enhanced the initial volume shrinkage and maximum dilation during the shear process, which is essentially governed by the rotation and alignment of the particles. The shear stress level primarily influenced particle crushing, with a maximum relative breakage index of 2.18%. In addition, a simplified calculation of the equivalent additional stress provided by the geogrid–particle interface was further developed under the horizontal and inclined reinforcements. Further, the potential correlations between the shear stress transfer coefficient and the determined parameters were clarified by analyzing the force and deformation characteristics of the geogrids. The presented findings are highly significant for understanding the geogrid–particle interaction mechanisms and the future application of reinforced geostructures in calcareous sand regions. [ABSTRACT FROM AUTHOR]

A thorough study was conducted to assess the performance of the strip footing reinforced with geocells in sand, focusing on understanding the enhancement effects and geocell reinforcement mechanisms. Critical factors such as geocell modulus, height, soil relative density and load eccentricity were examined through fully instrumented model tests. Measurements included surface displacement profiles, strains on the geocell layer, subsurface pressure distribution and other relevant parameters. Results revealed that the strip footing on geocell-reinforced sand beds exhibited better performance compared to those on unreinforced soil, characterized by increased load-carrying capacity and reduced settlements. Notably, stiffer geocells improved performance significantly, with a 40% higher modulus enhancing the bearing pressure by up to 25%, due to better confinement and anchorage effects. Conversely, geocells with a lower modulus demonstrated more effective vertical stress distribution. Furthermore, increased geocell height moderately enhanced footing performance by improving confinement, although wall buckling under eccentric loading limited major gains. Dense soils under centric loading exhibited up to a 20% better improvement in bearing pressure than loose soils due to higher strain mobilization within the geocell layer. These findings highlight the crucial role of geocell and soil properties, as well as loading conditions, in optimizing reinforcement effects for strip footings. • Assessed geocell-reinforced strip footings with fully instrumented tests. • Geocell footings outperform unreinforced soils, improving key non-dimensional factors. • Stiffer geocells notably enhance performance due to better confinement and anchorage. • Lower modulus geocells benefit from enhanced vertical stress distribution. • Increased geocell height moderately increased footing performance. [ABSTRACT FROM AUTHOR]

In this study, Recycled Concrete Aggregate (RCA) was employed as a sandwich technique around the geogrid to enhance the pullout resistance of the geogrid in clayey backfills. Large-scale pullout tests were conducted on three configurations: geogrid-reinforced clay, geogrid-reinforced RCA, and geogrid sandwiched between layers of RCA, aimed at investigating pullout resistance and deformation. The experiments encompassed two different geogrid types (designated as G1 and G2), varying normal pressures ranging from 10 to 50 kPa, and RCA layers with thicknesses of 40, 80, 160, and 320 mm. Results from the experiments revealed that the inclusion of RCA layers around the geogrid substantially enhanced pullout resistance, with improvements ranging from 1.5 to 3 times compared to clay specimens. Optimal RCA thicknesses were determined in order to enhance soil-geogrid bonding and pullout resistance. For G1 geogrid, a thickness of 160 mm (equivalent to replacing 25% of clay volume with RCA) was identified as optimal, while for G2 geogrid, an 80 mm thickness (equivalent to replacing 15% of clay volume with RCA) was found to be sufficient. These thicknesses were established to achieve over 80% of the pullout force compared to full RCA specimens. • Large-scale pullout tests were performed on two types of geogrids. • Recycled Concrete Aggregate (RCA) was utilized at various thicknesses within a sandwich technique to enhance geogrid pullout resistance in clayey backfills. • The optimum thickness of RCA layer in sandwich technique was determined. [ABSTRACT FROM AUTHOR]

Geogrid stabilized and reinforced base layers with bound superstructure over soft subsoil with high swelling capacity To quantify the stabilization and reinforcement effect of geogrids over soft, expansive clay subgrade, a full‐scale pavement field trial was established in 2018 in a rural residential area, south of Brisbane, Australia. Sections with variable geogrid arrangements were constructed to allow the quantitative assessment of geogrid benefit; both in terms of their initial contribution to composite in‐situ stiffness parameters and their benefit to the long‐term performance of the pavement. On site testing was completed within all trial sections during the project's construction phase, such that the initial state of performance the subgrade and each pavement layer was adequately characterized. The article describes the soil investigations, the construction of the test sections as well as performance monitoring results, three years after the road was opened to traffic. [ABSTRACT FROM AUTHOR]

The increasing use of geogrid in various geotechnical projects has made the evaluation of the shear behavior of soil reinforced with geogrid become particularly important. In this article, a series of large-scale direct shear tests have been performed on sand and gravel samples reinforced with geogrid. The purpose of the experiments was to investigate the impact of the geogrid mesh size and the relative density of the samples on the shear strength coefficient of the interface between soil and geogrid. In this study, 5 geogrids with different mesh sizes and one type of geotextile were used. According to the results, the average shear strength coefficient of sand and gravel samples reinforced with geogrid for different normal stresses and different relative densities was obtained between 0.72 and 0.94. As the relative density increases, the interface shear strength coefficient decreases, this means that the denser the sand, the more the shear strength of the sand/geogrid interface decreases. Based on the results, it was found that the contribution of particle interlocking in the shear resistance of the sand/geogrid interface is particularly important, so that the shear resistance coefficient of the interface increases with the increase in the size of the geogrid mesh. [ABSTRACT FROM AUTHOR]

This paper presents a mesoscopic evaluation of the shear resistance evolution of geogrid–aggregate interfaces subjected to direct shear loading. A three-dimensional discrete element method model was developed based on experimental data. The tensile response of geogrid were simulated through a series of calibration tests. Aggregate with complex particle shapes were simulated to accurately capture the interlocking effect among aggregates based on the real particle surface. The individual shear resistance components were quantified based on particle displacement field and contact distribution characteristics. The influences of aperture–aggregate size ratio and geogrid stiffness on the shear resistance components are discussed. The results indicate that the peak value of shear resistance component follows a descending order from frictional resistance of aggregate, to passive resistance of transverse rib, and to geogrid–aggregate interface frictional resistance. During the shear process, the frictional resistance of aggregate becomes active first, followed by the geogrid–aggregate interface frictional resistance, and then the development of passive resistance of transverse ribs starts with a certain lag. Optimizing the geogrid–aggregate size ratio and utilizing geogrids with higher rib stiffness could enhance the passive resistance of transverse ribs but would not significantly affect the geogrid–aggregate interface frictional resistance and frictional resistance of aggregate. [ABSTRACT FROM AUTHOR]

This paper provides insight into the causes of post-peak strength loss for textured geomembrane (GMX) and nonwoven geotextile (NGT) interfaces. The NGT can be part of a geosynthetic drainage composite (GDC) or a stand-alone NGT. The study used ring shear tests where one of the two interface materials was replaced after reaching a residual strength condition and the test was restarted to measure the change in interface strength. The interface strength loss from peak to large displacement (LD) strength primarily comes from three mechanisms: (1) geomembrane wear, (2) breakage and combing of fibers in the NGT, and (3) reduction of the hook and loop effect between GMX asperities and fibers of the NGT. The source of interface strength loss from LD strength to the residual value mainly comes from breakage and continuous combing of NGT fibers parallel to the direction of shear in ring shear tests. Scanning electron microscopy photographs of the GMX and NGT before and after shearing confirm wear and smoothing of GMX asperities and the combing of NGT fibers in the direction of shear. [ABSTRACT FROM AUTHOR]

This study investigated the performance of unreinforced and geogrid-encased cement-stabilized dredged slurry columns by uniaxial compression tests to simulate the extreme case where the surrounding soil offers no confinement. The objective was to understand the strength characteristics and visualize the deformation damage patterns of the columns with respect to the water content, cement content, length-to-diameter ratio, and geogrid strength. The results show that the unreinforced specimens exhibited strain-softening behavior, whereas geogrid encasement induced strain-hardening, with high-strength geogrids showing superior strain-hardening capacity. Notably, regardless of geogrid strength, encasement enhanced the resistance to deformation and ductility of the columns. Increasing the cement content, reducing the water content, and decreasing the length-to-diameter ratio all contributed to higher peak strength in both unreinforced and geogrid-encased specimens. Geogrid encasement provides confinement that enhances peak strength. The influence of geogrid encasement on peak strength becomes more pronounced at lower cement contents, higher water contents, and higher length-to-diameter ratios. Geogrid encasement also affects failure modes, altering the predominant inclined shear failure observed at the top of unreinforced specimens. Specimens encased with geogrids of higher tensile strength exhibit enhanced integrity and deformation resembling compression strut buckling, with a symmetrically inclined failure trend at the top and bottom. [ABSTRACT FROM AUTHOR]

Lateral restraint is the primary stabilization mechanism associated with the interlocking of aggregate particles in the geogrid apertures. This paper presents findings from a laboratory study which quantifies the local stiffness enhancement of aggregates through micromechanical interlocking provided by two different types of geogrids. These findings are applied to model the resilient response characteristics of geogrid-stabilized base course composite systems. Using three pairs of bender elements as shear wave transducers, horizontal stiffness profiles were determined above mid-heights of aggregate specimens. For two types of geogrids with square- and triangular-shaped apertures, the shear modulus profiles decreased moving away from the geogrid location. Based on a relationship for aggregates, resilient modulus was estimated from the shear modulus. Considering the variations in resilient moduli with distance from the geogrid location, the local stiffness enhancements provided by the two geogrid types were assigned to modulus profiles of a geogrid-stabilized aggregate base course in flexible pavement mechanistic analysis and modeling. The modeling results demonstrate the effect of geogrid base stabilization on the computed pavement resilient responses for both geogrid types. The sublayering approach which properly considers modeling of the geogrid influence zone could be effectively used in mechanistic analysis of a geogrid-stabilized pavement system. [ABSTRACT FROM AUTHOR]

Cement-mixed soil has been widely used in road and railway construction. Mixing cement with soil increases its bearing capacity, stiffness, and shear strength while reducing the compressibility and volume changes of the soil. However, using only cement can lead to sudden and brittle failure due to the low tensile and flexural strengths of cement-mixed soils. In this study, the flexural strength and deflection behavior of cement-mixed sand, reinforced with geogrids (single and dual layers) and short fibers (0.5% and 1%), were investigated. Two types of biaxial geogrids were employed, along with polyvinyl alcohol (PVA) fibers measuring 12 mm in length and 0.1 mm in diameter. Standard silica sand and 6% ordinary Portland cement (OPC) Type I served as the sand and binding materials, respectively. Fifteen beam specimens, each measuring 15x15x53 cm, were prepared and cured for 28 days before testing. The experimental findings revealed that both the fiber content and the addition of biaxial geogrids improved the flexural behaviour of the cement-mixed sand. Specifically, incorporating fibers (0.5% and 1%) and dual-layer geogrids increased the first peak (f1) strength by 1.25 times and the peak strength by 2.53 times. Additionally, this reinforcement strategy enhanced crack patterns and distributed flexural loads across different parts of the beam specimens, resulting in multiple crack failure modes. Overall, the combined use of geogrids and fibers effectively reinforced the cement-mixed soil, producing a stress-deflection curve similar to that of steel bar-reinforced concrete, an improved failure mode, and the highest flexural strength. [ABSTRACT FROM AUTHOR]

A bamboo grid is a new type of reinforcement material, which can replace traditional geogrids in the reinforcement of embankments. In this study, the reinforcement effect of the bamboo grid that is only set at the interface between the filled and undisturbed soils of the filled loess embankment in a high and steep gully was investigated. The influence of reinforcement position and grid spacing on the reinforcement effect was studied by carrying out a large-scale direct shear test, numerical simulation, and field measurement. The results indicated that the bamboo grid could enhance the shear strength of the reinforcement interface. The interface shear strength first improved and then decreased with the decrease in grid spacing. The differential settlement was significantly reduced after the reinforcement of the bamboo grid at the interface. Compared with other reinforcement positions, setting the bamboo grid in the upper part of the embankment was the most efficient and economical. When the grid spacing became dense, the reinforcement effect was improved as the differential settlement decreased. However, the improvement in the reinforcement effect by decreasing the grid spacing was limited, which meant there was an optimal grid spacing. [ABSTRACT FROM AUTHOR]

Deep buried tunnels face high in-situ stress during the construction process, which can easily trigger rock burst. Flexible protective system is an important way to achieve disaster control. Regarding the problem of low toughness and inability to resist instantaneous impacts in the existing flexible protective materials, this study develops a high-strength and high-toughness flexible geogrid based on three deformation modes that may occur when it intercepts explosive blocks. This process considers the selection of polymer fiber filaments, optimization of weaving methods, and improvement of fabric structure. The stress and deformation characteristics of flexible geogrids are analyzed through single-rib tensile, nodal peel, and static jacking tests. The tests showed that mechanical performance of the flexible geogrid can meet requirements for strong and below level rock burst. To analyze the effects of strip strength strip, elongation at break, and nodal strength on the characteristics of jacking deformation, numerical simulations are conducted based on the discrete element method. The results showed that the elongation at break is controlled within 13%, the strip strength is greater than 0.8 GPa, and the nodal strength is increased to 0.075 GPa or above, which can significantly improve the rock-burst protection ability of the flexible geogrid. Finally, the impact energy absorbed by the flexible geogrid reached 74.23 kJ through the falling ball impact experiment, and the engineering application of the flexible geogrid is achieved in the rock-burst section of the Duoji Tunnel on the CZ Railway. [ABSTRACT FROM AUTHOR]

Cement-stabilized crushed stone is widely used in the construction of high-grade highways because of its good durability and stability. However, cement-stabilized gravel is also easily affected by temperature and humidity, resulting in a reduction in the overall strength and durability of asphalt pavement. In response to this problem, in this study, we lay a single layer of a basalt fiber geogrids in a cement-stabilized gravel base of a test section of the Yan-Chong Expressway. The bonding and friction forces formed between the basalt fiber geogrids and the base as well as the mechanical bite force, play an anti-cracking role. We conducted a comparative experimental study on the mechanical properties of basalt fiber geogrids reinforced or not reinforced with cement-stabilized gravel specimens of different ages. The results showed that (1) the unconfined compressive strength of cement-stabilized gravel was slightly reduced; (2) the splitting strength was somewhat improved; (3) the compressive elastic modulus was slightly reduced; (4) the flexural and tensile strengths were significantly increased. An improvement in the crack resistance in semi-rigid base materials can improve the service life of high-grade asphalt pavements. [ABSTRACT FROM AUTHOR]

This study evaluates the performance of a geosynthetic reinforced soil integrated bridge system (GRS-IBS) in terms of total displacement by varying different design parameters simultaneously and also suggests optimum values of them. These parameters include, i. backfill internal friction angle (çb) and reinforcement spacing (Sv), ii. Backfill internal friction angle (çb) and geogrid axial stiffness (EA) at varying reinforcement spacing (Sv), iii. Backfill internal friction angle (çb) and number of bearing bed layers, and the effect of retained backfill slope (mb). Simulations were conducted using PLAXIS 2D software. Analysis showed that the cumulative effect of these parameters had a significant effect on total displacement but after a certain point increase or decrease in their values showed no effect on the results while some parameters showed negligible effect on the deformation of the wall. Furthermore, due to the notable effect of çb, Sv and EA on the total displacement of the wall, the impact of these parameters was also investigated on the development of tensile force in the topmost layer of geogrid in GRS IBS. It was noted that the shape of the tensile force distribution graph was the same for all the cases and the order of the parameters in terms of their effect on tensile force was Sv > çb > EA. Also, a detailed analysis of tensile force development in all the layers of geogrids showed that if Sv = 0.2 m, the spacing between reinforcement in the lower portion of GRS IBS can be increased as these layers showed approximately zero tensile load. [ABSTRACT FROM AUTHOR]

To investigate the installation damage of geogrids during roller compaction under rockfill condition, a three-dimensional discrete element model for roller compaction of geogrid-reinforced rockfill was established. The rockfill was modeled by irregular rigid block elements, while the geogrids were modeled by bonding basic ball elements. The model parameters were then calibrated by triaxial consolidated-drained and tensile tests. The displacements of the geogrids in three perpendicular directions, and the strength of the geogrids was analyzed. Additionally, the effects of compaction parameters on the installation damage of the geogrids were studied. The results showed that deformation of the geogrids was relatively small in the roller-driving direction but significant in the roller-axis and settlement directions. The damage modes of the geogrids could be mainly classified into three types: rib fracture, rib end fracture, and node fracture. The installation damage of the geogrid was derived mainly from its uneven deformation and fracture, and after roller compaction the strength distributions at different locations of the geogrid layer showed a normal distribution. Furthermore, the installation damage of the geogrids increased with increasing excitation force and compaction passes but decreased with increasing overlying rockfill thickness, roller velocity, and excitation frequency. • The installation damage of the geogrids was studied by the discrete element method. • The deformation and strength of the geogrids were analyzed. • The effects of compaction parameters were also investigated. [ABSTRACT FROM AUTHOR]

The effective interaction mechanisms in the pullout resistance of reinforcements include skin friction mobilized at the soil-solid surface, soil-soil shear resistance, and compressive resistance created against transverse elements. The third component is obtained from passive lateral pressure (LPM) or bearing capacity (BCM) methods. An analytical solution is proposed to determine the pullout capacity of geocell, geogrid, and strengthened geogrids embedded in ordinary and unsaturated soils. For unsaturated soils, the effective stress approach was employed. The solution-predicted results were compared with those obtained from large-scale pullout tests reported in the literature. Results indicated that considering LPM for 2D and 3D reinforcements better agrees with experimental results. The mobilized frictional rib-soil interfaces and the soil-soil shear resistance components generally contribute more to the pullout capacity of the geocell and geogrid, respectively. For the extensibility represented by m p i and flexibility of geocell denoted by α p i , the values of m p i = 1, 0.7, and 0.3 for the first, second, and third row of geocell, α p i = 0.4 for the first row of geocell and 0.25 for the second and subsequent rows are suggested to be considered. Parametric studies showed that the optimum transverse rib spacing is over 50 times the equivalent rib thickness (B eq). • To develop a solution based on the lateral earth pressure and bearing capacity methods to determine the pullout resistance of three-dimensional (3D) reinforcement such as geocell and two-dimensional (2D) reinforcement like geogrid and strengthened geogrids. • Validating the proposed equation for reinforcement pullout resistance in unsaturated soil, based on effective stress. • Investigating the present solution outcomes with 162 pullout tests performed on 28 different types of reinforcement, extracted from 10 case studies. • Proposing a method to reduce the passive resistance of geocell transverse ribs, related to the effects of extensibility and flexibility. • Presenting an evaluation method considering the geocell geometry and soil matric suction on the pullout capacity of geocells and the effects of the transverse rib spacing and width on the pullout capacity of geogrids. [ABSTRACT FROM AUTHOR]

Geosynthetic-reinforced soil (GRS) walls built on hillslopes are more increasingly incorporated with geo-composite side drain in order to prevent the side-seepage entering the fill. This study evaluates the long-term moisture, pore-water pressure, and shear modulus, of a 6.5 m-high geogrid-reinforced soil wall in western Thailand. Through extensive field monitoring and in-situ spectral analysis of surface wave (SASW) tests, conducted during the Years 2018–2019, as well as laboratory tests, several key findings emerge. Free-free resonant frequency (FFR) testing of non-reinforced samples reveals the role of soil wetting and drying history and hysteresis in the stiffness-moisture relationship. In-situ pore-water pressure was found to be highest below the road surface near the wall face, decreasing with depth due to underdrainage, with values ranging from −27 to 5 kPa. The intersection of the side drainage board with the underdrain bottom layer shows the highest water content. In-situ and laboratory-derived soil-water retention curve (SWRC) were found to differ at greater depths. In unsaturated conditions, the in-situ small strain modulus of GRS appeared insensitive to suction stress below 10 kPa but was slightly affected under positive pore-water pressure, with multiple linear regression modeling indicating a dependency of stiffness on depth and pore-water pressure. • Uncertainties persist regarding pore water pressure distribution in the fill when designing geosynthetic-reinforced soil walls. • This study evaluates the long-term moisture, pore-water pressure, and shear modulus, of a 6.5 m-high GRS wall with modular side drains. • Pore-water pressure was highest near the wall face just below the pavement, and diminished with depth due to underdrainage. • In-situ G₀ of GRS wall was insensitive to suction stress in unsaturated conditions but slightly affected once the soil became saturated. [ABSTRACT FROM AUTHOR]

Reinforced calcareous sand is increasingly recognized as a promising roadbed filler. This study evaluated the effects of different reinforcement methods, rubber content, dynamic stress amplitude, and loading frequency on calcareous sand through stress controlled undrained triaxial tests, and studied the dynamic characteristics and particle crushing of reinforced calcareous sand. The results showed that geogrid reinforcement increased the occurrence of particle fragmentation in calcareous sand and had the ability to resist deformation of rubber–calcareous sand mixtures, but the addition of rubber retarded particle fragmentation. In the case of geogrid reinforcement, the increase in rubber particle content from 0 to 10% corresponded to a 23.9% decrease in relative particle fragmentation. In the case with rubber particle reinforcement only, after 1000 cumulative loading cycles, the cumulative axial strain of the specimens increased 2.9 times when the rubber content was increased from 10 to 30%; the cumulative axial strain increased 60.7% when the amplitude of the dynamic stress was increased from 40 to 80 kPa; and the cumulative axial strain decreased 1.7% when the loading frequency was increased from 0.5 to 2 Hz, from 2.46 to 1.825%. The results of the study can provide reference and guidance for practical engineering. [ABSTRACT FROM AUTHOR]

A detailed numerical analysis has been accomplished to explore the influence of geometrical parameters of geocell reinforcement on the load carrying behavior of footing using three-dimensional finite element techniques. The influencing parameters considered such as shape, height, pocket size, stiffness of geocell reinforcement, and friction angle of infill materials. Results indicate that the inclusion of the geocell reinforcement irrespective of the shape of geocells significantly enhances the strength and stiffness of the foundation system. However, the pressure-settlement behavior is noticeably influenced by the shape of the geocells. The load carrying capacity is found to be minimum for square shaped (i.e., 400 kPa) followed by circular, diamond, and honeycomb shapes (i.e., 1000 kPa) of geocells. With increase in height of geocell mattress, the performance of the foundation system increases noticeably. The findings indicate that the load bearing capacity increases significantly up to a height ratio (H/B) of 1.5, beyond which further increment found to be marginal. Additionally, the efficacy of the system improves with increase in stiffness of reinforcement and reduces with increase in geocell pocket size. Furthermore, it is evident that the higher frictional angle of the soil mobilizes enhanced resistance on the interface, improving the overall performance. [ABSTRACT FROM AUTHOR]

The effect of thermal-oxidative ageing on in-isolation and in-soil stiffness is investigated for two high-density polyethylene (HDPE) and two polyester (PET) geogrids when incubated in an oven at 90°C. It is shown that the in-isolation and in-soil stiffness of three out of the four geogrids decreased during the 4-month ageing time with a faster degradation of the two PET geogrids. In contrast, one of the HDPE geogrids examined with thicker rib showed slower degradation compared to the PET counterparts. It is also shown that a geogrid might have a higher unaged stiffness, but less aged stiffness compared to another geogrid made of the same polymer type. It is suggested that the ageing approach used in this study could be adopted for the selection of geogrids based on their long-term stiffness for structures such as reinforced embankments or mechanically stabilized earth walls that require a long service life. Moreover, results indicate that the stiffness improvement factor for PET geogrids decreases with ageing time. On the contrary, the stiffness improvement factor of the HDPE geogrid increases with time and hypothetically might keep increasing followed by a sudden drop to zero at full degradation of the geogrid. [ABSTRACT FROM AUTHOR]

Geocell reinforcements are proposed as a thrust countermeasure for shallowly buried pipeline bends and tees. The proposed method is easy to construct and has shorter construction time than the use of conventional concrete blocks since it does not require curing. Lateral loading tests were conducted on plates reproducing pipe bends or tees to verify their effectiveness while understanding deformation mechanisms. In addition to changing the plate width and geocell pocket size, additional experiments were conducted with different geocell reinforcement dimensions, geocell tensile stiffnesses and tensile properties of the seams. An equation for predicting the force–displacement relationship was developed as part of the proposed design method. The experimental results showed that the sides of the reinforced ground were not fully integrated when the width of the geocell reinforcement was large relative to the plate width. It was also found that the maximum force hardly decreased, although the displacement increased slightly due to the reduction of the tensile stiffness of the geocells and the tensile force at the geocell seams. Moreover, a hyperbolic approximation of the force–displacement relationship of the geocell reinforcement was developed and the calculated values agreed well with the experimental values. [ABSTRACT FROM AUTHOR]

The use of alternative reinforcement material to enhance the performance of the pile capacity has gained increasing interest in recent years. This study seeks to probe the improvement of the ultimate pile capacity, reduction the deformation, and the financial results of using alternative reinforcement material such as glass fiber-reinforced polymers (GFRP), geosynthetics geogrids, as well as a combination of geosynthetics geogrids and a central steel bar. Axial load investigations were conducted on circular piles with 150 mm diameter and 1050 mm height. The experimental results revealed an improvement in the axial capacity of up to 25.4% and an enhancement in performance represented in ductility. Furthermore, financial and weight comparisons showed a decrease in the cost by up to 15%. Moreover, a nonlinear finite element (FE) study with Abaqus software was employed to standardize the numerical outcomes with the laboratory findings. The FE analysis was also verified with the previous studies. The 3D nonlinear finite element numerical model performed showed convergence with and without representing the surrounding soil of the pile; thus, confirming the adequacy of the experimental setup adopted. Finally, a suggested theoretical equation is developed to evaluate the change in pile axial load capacity based on the use of different reinforcement materials. The application of the proposed theoretical equation provides further insight into the governing equation involving different reinforcing materials. [ABSTRACT FROM AUTHOR]

This paper introduces a new retaining structure, multi-step cantilever retaining walls pulled locally with geogrids, which has advantages of light weight, quick installation and good applicability for high fill earthworks. Considering log-spiral rotation failure mechanism passing by the heel of the lowest wall members as well as pull-out failure and tensile rupture of the flexible reinforcements, an analytical procedure for seismic overall stability of the retained embankment is proposed based on the upper-bound limit analysis method combined with pseudo static approach. Analysis results of a practical example show that the proposed safety factor and critical slip surface are identical with those by numerical simulation method via FLAC3D. The safety factor increases approximately linearly with the ultimate tension force and the number of reinforcements and nonlinearly with the length of reinforcements within a certain range. Horizontal seismic force has noticeable effect on the slope stability, and vertical seismic effect becomes significant under high horizontal acceleration coefficient. The safety factor is decreasing and the critical slip surface develops obviously towards the embankment exterior as the total number of vertical wall members increases. Besides, the distribution width and setback distance from the walls of the strip surcharge have certain effects on the retained slope stability. [ABSTRACT FROM AUTHOR]

Experimental studies on the influence of geogrids in unbound base layers In railroad construction, base layers of unbound coarse‐grained material are usually installed between the existing subsoil and the rail track. Geosynthetics, in particular geogrids, are used to improve the system behaviour. The reduction of the base layer thickness by the geogrid is based on empirical approaches. The influence of the geogrid on the load‐bearing behavior of a base course is to be quantified by experimental investigations. The investigation is performed using a downscaled base course material and geogrid. For this purpose, monotonic and cyclic triaxial tests were performed to demonstrate the failure and the cyclic loading behaviour. In the monotonic triaxial tests the specimens were sheared to failure. The positive influence of the geogrids compared to the unreinforced specimens could be quantified. Since the in‐situ stresses are mainly in the service load range and thus the failure state is not reached, but the stress follows a high number of load cycles, cyclic triaxial tests were performed. The test specimens were loaded cyclically in order to investigate the influence of the geogrid on the deformation accumulation. The cyclically loaded specimens thus show the influence of the geogrid on deformation accumulation. As a result, a reduction in deformation accumulation due to the geogrid could be demonstrated. [ABSTRACT FROM AUTHOR]

One of the most popular methods for improving weak soil properties is soil reinforcement with geogrid-layers, the geogrid-layer increases the low shear resistance of fine sand. The Abaqus 3-D model is utilized to simulate large-scale direct shear apparatus. Numerical models are conducted on geogrid-reinforced fine sand to estimate how geogrid-axial stiffness affects the shear strength behavior. Shear parameters, shear strength ratio, internal shear coefficient, and mobilized geogrid tensile strength are studied in both longitudinal and transverse directions. The steel box for large-scale direct shear consists of two separate parts with dimensions of 200 mm x 200 mm x 100 mm. A geogrid-layer with different axial stiffness between 200 kN/m and 1000 kN/m with an increment of 100 kN/m is fixed between the two separate parts to estimate the shear resistance increase of geogrid-reinforced fine sand. The shear strength of geogrid-reinforced fine sand increases with geogrid-axial stiffness; for the fine-sand elastic modulus of 10 MPa, the shear strength ratio (SSR) increases from 1.80 to 3.10 when the geogrid-axial stiffness increases from 200 kN/m to 1000 kN/m. However, the (SSR) values decreased with increasing fine-sand elastic modulus, the (SSR) values were 1.0 and 1.60 for the variation of geogrid-axial stiffness from 200 kN/m to 1000 kN/m when the fine-sand elastic modulus increased to 40 MPa. The most economical and optimal values of geogrid-axial stiffness are 500 kN/m and 300 kN/m for fine-sand elastic moduli of 10 MPa and 40 MPa, respectively. [ABSTRACT FROM AUTHOR]

The tensioned reinforced soil retaining wall, a novel retaining structure, utilizes either anchors or geosynthetic materials as reinforcements that contribute to load-bearing and friction within the structure. This study aims to explore the tension distribution and strain patterns in the reinforcements, and their influence on the reinforced soil retaining walls. To this end, tensile, direct shear, and pullout tests were conducted on GeoStrap@5-50 geotextile strips and TGDG130HDPE geogrids to evaluate the tensile strength and interface strength between the reinforcement and the soil. The characteristics of the reinforcement–soil interface and the deformation behavior under stress were examined, with a comparative analysis of the technical merits of the two types of reinforcements. The results indicate that both the geotextile strips and geogrids enhanced the strength of the reinforced soil, primarily by increasing cohesion. The GeoStrap@5-50 geotextile strips exhibited superior tensile strength compared to the TGDG130HDPE geogrids; the reinforcement with the geotextile and geogrids both enhanced the cohesion of the standard sand, albeit with a slight decrease in the internal friction angle, by 4.6% and 3.1%, respectively, offering enhanced mechanical properties and economic value in reinforced soil retaining wall applications. [ABSTRACT FROM AUTHOR]

The intensification of extreme weather phenomena, ranging from torrential downpours to protracted dry spells, which trigger fluctuations at the groundwater level, poses a grave threat to the stability of embankments, giving rise to an array of concerns including cracking and differential settlement. Consequently, it is crucial to embark on research targeted at uncovering the settlement and deformation behaviors of pile-supported embankments amidst changes in water levels. In tackling this dilemma, a series of direct shear tests were carried out across a range of wet–dry cyclic conditions. The results confirmed that the occurrence of wet–dry cycles significantly impacted the resilience of silty clay. Additionally, it was observed that the erosion of cohesion and the angle of internal friction initially diminished sharply, subsequently leveling off, with the first wet–dry cycle exerting the most substantial influence on soil strength. Employing a holistic pile-supported embankment model, simulations revealed that variations in the groundwater level, fluctuations therein, varying descent rates, and periodic shifts in the groundwater level could all prompt alterations in soil settlement between embankment piles and could augment the peak tensile stress applied to geogrids. In summary, the orthogonal experimental method was utilized, indicating that, in terms of impacting embankment settlement under periodic water-level changes, the factors ranked in descending order were the following: pile spacing, pile length, embankment height, and the height of the groundwater table. [ABSTRACT FROM AUTHOR]

This manuscript presents a mini review on the potential new application of geocell in the mitigation of ground vibration. An effort has been made to provide a detailed quantification and mechanisms involved in the vibration isolation performance of geocells. The latest studies on the topic are summarized in three sections, namely, experimental, numerical, and analytical studies. Details on the optimum dimension of geocells, depth of placement, and suitable infill materials for effective isolation of vibrations have been covered. Further, the mechanism responsible for the superior vibration isolation performance of the geocells is highlighted. In addition, analytical equations and machine learning-based models for predicting the isolation performance of the geocells are discussed. The study reveals that geocell is very effective in isolating ground vibrations as compared to other forms of geosynthetics. Geocells were found to enhance dynamic properties and reduce the amplitude of vibrations significantly. [ABSTRACT FROM AUTHOR]

This study aims to explore the accumulated behavior of reinforced coarse-grained soils through cyclic triaxial tests and to develop a prediction model for the plastic shakedown limit. Cyclic triaxial test results illustrate that the reinforced specimens, especially those incorporating geocells, demonstrate the lowest accumulated axial strain and the highest plastic shakedown limit when compared to unreinforced ones under identical cyclic loading. Additionally, the accumulated axial strain at the plastic shakedown limit for reinforced specimens is determined. This strain is then used to determine the additional confining pressure exerted by geogrid or geocell, employing a function proposed by Yang and Han. By integrating the additional confining pressure into the plastic shakedown criterion for unreinforced specimens, a prediction model for the plastic shakedown limit in reinforced specimens is ultimately established. The model's applicability and the accuracy of computed additional confining pressure values are validated using experimental data. • Cyclic triaxial tests are conducted to investigate the coarse-grained soil. • The influence of reinforcement types on the accumulation behavior is analyzed. • The plastic shakedown limits of two types reinforced specimens are determined. • A prediction model is proposed to determine the soil's plastic shakedown limit. • The accuracy of the proposed model is validated using the experimental data. [ABSTRACT FROM AUTHOR]

To enhance the mechanical properties and stability of desert railway embankments, the utilization of geogrids has proven to be an effective measure. The article conducted field tests and discrete element simulations to thoroughly examine the static performance of embankments reinforced with geogrids. The study systematically explored the macroscopic and microscopic characteristics of the geogrid-reinforced embankment under static loading. Various factors were investigated, including the horizontal laying arrangements and depth to the top layer of the geogrid, as well as key design parameters such as the number of geogrid layers, geogrid width, and vertical spacing between geogrid layers. The findings indicate a progressive enhancement in the ultimate bearing capacity of the embankment with an increase in both the number of geogrid layers and the geogrid width. Conversely, there is a decrease in ultimate bearing capacity as the depth to the top layer increases. In comparison to unreinforced embankments, reinforced embankments exhibit a reduced contact anisotropy, signifying that the geogrid effectively disperses static loads, resulting in a more uniform contact distribution. The geogrid restrains both displacement and rotation of the aeolian sand, and this restraining effect progressively strengthens with an increase in the number of geogrid layers or the geogrid width. The research findings can serve as a reference for the design and application of aeolian sand railway embankments. • We conducted triaxial tests on aeolian sand, single rib strip tests on geogrids, and field tests of geogrids reinforced aeolian sand embankments. • Additionally, we developed a two-dimensional discrete element embankment model to investigate the impact of geogrid parameters on the macro and micro performance of reinforced embankments. [ABSTRACT FROM AUTHOR]

To evaluate the benefit of geocells of different geometrical configurations for pavement application, full-scale instrumented model tests were performed on pavement sections reinforced with geocells of different geometrical configurations subjected to monotonic and repeated loading. The responses studied were stress distribution in different pavement layers, induced strains in geocell walls, and settlement characteristics. The reinforced sections exhibited a significant reduction in rut depth as well as localized stress concentration compared to the unreinforced section. The reduction in rut depth was found to be influenced by the geocell height as well as weld spacing. The geocell reinforcement was found to distribute the stresses in the subgrade and subbase layers more efficiently, thus reducing the stress concentration in these layers. The strain measurements were found to be higher at the bottom of the geocell walls indicating a higher confinement effect on a lower part of the geocell. In the field, mostly geocells of 356 mm weld spacing and 150 mm height (SW356-H150) are used. However, this study suggests that a geocell of 330 mm weld spacing and 100 mm height (SW330-H100) having approximately 30% lower cost compared to SW356-H150 is as effective in reducing the rut depth and localized vertical stress distribution. • Effect of weld spacing and heights of geocell reinforcement on pavement section is evaluated through full-scale model testing. • Study highlights that the reduction in rut depth is significantly influenced by the geocell height and weld spacing. • Geocell reinforcement reduces stress concentration in the subgrade and subbase layers by distributing stresses efficiently. • Higher strain measurements at the bottom of geocell walls indicate higher confinement at the lower part of geocell wall. • Study suggests use of SW330-H100 configuration of geocell as an economic alternative to conventional SW356-H150 configuration. [ABSTRACT FROM AUTHOR]

Reinforcing calcareous sands with geogrids is a potentially effective method for large-scale geotechnical constructions in coastal lands. The breakable nature of polygonal calcareous sands determines the complex particle-geogrid interactions. A three-dimensional numerical model of geogrid reinforced calcareous sand (GRCS) was established to investigate the potential mechanical laws based on the discrete element method (DEM), and the reasonableness of the numerical model was verified by comparing with the indoor triaxial test. It follows that the macro-microscopic mechanical behavior of GRCS under the influence of aperture size and tensile resistance of geogrids was further investigated via effective DEM simulations. The presented results show that the decreased aperture size and increased tensile resistance are beneficial to enhance the macro-mechanical properties of GRCS, including strength, internal friction angle and pseudo cohesion. Particle crushing is mainly affected by shear strain and confining pressure. The bulging deformation of GRCS is partially suppressed due to the confining effect of geogrids. Besides, the source of strength enhancement of GRCS is revealed based on the microscopic particle-geogrid interactions, and the calculation method of horizontal and vertical additional stresses in the reinforced soil element considering the effects of tensile resistance and aperture size is further established. • A DEM model is established for geogrid reinforced calcareous sand. • Aperture size and tensile resistance effects are considered. • The distribution and evolution of particle crushing are characterized. • The macro-micro mechanical behavior of GRCS is revealed. • An additional stress calculation method is developed. [ABSTRACT FROM AUTHOR]

Most of the world's railways run on ballasted track. However, ballast accumulates differential settlement with trafficking, hence the correct track level must be restored periodically – typically by tamping, which is costly. To reduce the cost of maintenance, several interventions have been proposed with the objective of increasing the interval between tamps by reducing the rate of differential settlement. These include broader ballast gradings, geogrids and under-sleeper pads. A possible alternative is the addition of unbound random fibres to the ballast. Fibres formed from polymer materials, randomly mixed with sands and gravels, have been shown to increase their shear resistance owing to the additional effective confinement associated with the mobilisation of tension in the fibres. However, the effect of the fibres on the permanent strain accumulated under cyclic loading has not been extensively investigated. This paper presents the results of an experimental programme carried out to assess the performance of full-size ballast reinforced with different proportions of polyethylene strip fibres of different lengths and widths. It shows that the addition of a moderate amount (0·6–0·7% of the volume of solids) of narrow fibres has negligible influence on grain packing and can reduce ballast plastic settlement without affecting track resilient stiffness. [ABSTRACT FROM AUTHOR]

Geogrids, first developed in the late 20th century, revolutionized soil reinforcement using polymer materials in grid-like structures to enhance soil stability, reduce erosion, and strengthen infrastructure, marking a pivotal advancement in geotechnical engineering. However, geogrids typically find limited application in structural engineering, especially reinforced concrete (RC) columns. The present research explores the feasibility of geogrids in concrete columns, thus optimizing construction practices by exploring innovative reinforcement methods beyond conventional steel, aiming to bolster durability and performance in diverse structural scenarios. The traditional method of using steel stirrups to confine circular columns was substituted with a new approach; i.e., geogrids were introduced partially as confining material alongside steel stirrups. Furthermore, the research examines the performance of concrete columns confined partially with geogrid, both with and without the inclusion of steel fibers, in comparison to traditional columns reinforced with steel. Columns, 16 in number, with different steel stirrup spacing, concrete types, and geogrid configurations, were cast and put under axial load. Load-deflection curves were obtained, and parameters including ultimate load, maximum axial displacement, ductility, secant stiffness, and energy dissipation were assessed and compared. The findings indicated that incorporating geogrids with greater tensile strength alongside steel fibers could uphold a peak load value 10.16% higher than the control column, improved stiffness, and enhanced energy dissipation, indicating a promising approach for reinforcing columns in conjunction with steel fibers. [ABSTRACT FROM AUTHOR]

Although the efficacy of stone columns as a ground improvement technique for soft soils is well-established, their effectiveness diminishes in very soft soils (qu < 25 kPa) due to insufficient lateral support. In such situations, encasement with geosynthetics may be beneficial. This paper presents the results of model tests on various types of stone columns (floating and end-bearing) with different diameters (40 mm and 60 mm), both ordinary and geogrid-encased, in very soft clay with varying undrained shear strengths. The tests were conducted under monotonic and cyclic loading conditions in a plane-strain configuration. The study evaluates the impact of key parameters, including column length and diameter, base support conditions, undrained shear strength of clay, and geogrid encasement length, on the performance of improved ground through a total of 28 model tests. The results show that regardless of the soil's undrained shear strength, the encasement of stone columns with geogrids significantly enhances ground performance. Under monotonic loading, this improvement ranges from 22 to 140% depending on the length of geosynthetics encasement and base support conditions. Under incremental cyclic loads, the improvement varies from 25 to 50%. It is also observed that the geogrid encasement's effectiveness significantly increases when it encompasses the entire length of the stone columns, as it extends the lateral bulging zone below the encasement length. [ABSTRACT FROM AUTHOR]

In the context of COVID-19 rampant worldwide since 2019, the stock of disposable single-use face masks (SUFMs) has climbed steadily, which results in an urgent worldwide environmental problem. This study aims to propose a potential method for processing and utilizing SUFMs in soil reinforcement to address the significant volume of discarded masks, thereby contributing to geotechnical engineering construction. Hence, in this study, SUFMs were prepared into three geosynthetic forms considered potential candidate options: fibers, geotextiles, and geocells. The performance of geosynthetics-reinforced sand was assessed by the static triaxial tests by considering the fibers reinforcement with the content of 0.25% and 1.0%, single-layer and three-layer geotextiles reinforcement, and geocells reinforcement. A series of numerical simulations were also conducted to investigate the failure mechanisms of various reinforced forms. The experimental results show that the three geosynthetic types can improve the sandy soil's shear strength and apparent cohesion. The SUFMs fibers reduce the elastic modulus due to the higher compressibility of the SUFMs, while the elastic modulus of geotextile and geocell-reinforced soil samples is elevated. The numerical analysis results indicate that the SUFMs fibers and geotextiles can limit the lateral deformation and spread the shear stress over a wider area through the interface friction between geosynthetics and soil. On the other hand, the vertical walls of geocells can provide direct lateral restraint, and the reinforcement effect is more direct and better. [ABSTRACT FROM AUTHOR]

In this study, we proposed a new method for preventing the uplift of a pipe using geocells, to improve the workability of the pipelines and increase the uplift resistance. As a fundamental study, push-up tests were conducted on the model pipe to verify the effectiveness of the geocell reinforcement. The experimental results showed that geocell reinforcement increased the peak resistance by more than 1.5 times and the resistance at large displacement (at a displacement of 40 mm) by more than 3 times at maximum, compared to the unreinforced method, indicating that geocell reinforcement is an effective countermeasure against pipe uplift. The combination of geocells and geotextiles increased the resistance at large displacement (at a displacement of 40 mm) by 1.41 times more than only geocell, contributing significantly to the increase in uplift resistance. In particular, increasing the number of geocells downward from the top of the pipe (on the side of the pipe), and integrating the left and right geocells with the geotextile, increased considerably the peak resistance and resistance at large displacement (at a displacement of 40 mm). • Novel method to prevent uplift of pipes using geocells proposed. • Geocell reinforcement achieves greater resistance against pipe uplift. • Better resistance achieved when there are more geocells below the top of the pipe. • Uplift resistance increased greatly with a combination of geocell and geotextile. [ABSTRACT FROM AUTHOR]

Seismic occurrences have caused severe damage and even the collapse of fragile unreinforced masonry structures. New technologies are replacing these conventional methods of construction; concrete sandwich panels (CSP) are one such technique gaining popularity. In-plane diagonal shear strength of concrete sandwich panels is studied experimentally, and the effect of incorporating geogrids on the deformation capability and load-bearing capacity is reported. Two forms of geogrid material, plastic uniaxial geogrid (PUG) and polyester biaxial geogrids (PBG2 and PBG3) are used to improve the strength and ductility of concrete sandwich panels. Diagonal compression tests have been carried out better to understand the behavior of CSP under in-plane strength. This paper also discusses the effect of the different mixes, the effect of geogrids, load-deformation behaviour, shear capacity, deflection ductility factor, mode of failure, shear strength, and energy dissipation. In contrast to the control specimen, specimens cast with plastic geogrid had a 13.7% and 26% improvement in shear capacity and load-bearing capability for the two types of micro-concrete mixes used in this study. The conclusion reached is that plastic uniaxial geogrid is effective in improving the concrete sandwich panels' load-bearing capacity, shear capacity, and deformation ability. Polyester biaxial geogrids enhanced the ductility of the concrete sandwich panels. [ABSTRACT FROM AUTHOR]

Under long-term loading, the mechanical properties of geogrids in eco-bag reinforced soil retaining walls (ERSW) gradually weaken due to creep and photo-oxidative aging. In contrast, the continuously growing roots transfer their tensile strength to soil shear strength. However, the reinforcing effect of plant roots within retaining walls is often overlooked in current research and design. This study investigated the reinforcement effect of plant roots and geogrids on ERSW stability through theoretical derivations using the Swedish circle method for roots penetrating potential sliding surface and two-wedge method for shallow roots. The results showed that their synergistic reinforcement effect affords the highest overall stability of ERSW under loading. Additionally, the compensation ability of roots was investigated by vertically loading a scaled ERSW model with palm leaves and designing 16 sets of controlled tests with two geogrid lengths, three geogrid spacings, and four root lengths. The horizontal displacement of the facing, horizontal earth pressure behind the eco-bags, and geogrid tensile strain under various conditions decrease by 5.47%, 3.71%, and 4.17%, respectively, with increases in the unit length of the geogrid, and by 3.625%, 1.411%, and 4.713%, respectively, with increases in the unit length of roots. In the three parameters, the compensation rates of the root for the geogrid length are 0.66, 0.38, and 1.13, respectively. The reduction rates of the three parameters are 34.38%, 45.26%, and 58.62% with the geogrid spacing decreasing from 30 cm to 20 cm under the no-root condition, and the rates change to 56.25%, 21.14%, and 63.22% with a geogrid spacing of 30 cm and the addition of 15 cm long roots, respectively. In the three parameters, the compensation rates of 15 cm length roots for the geogrid spacing are 1.64, 0.47, and 1.08, respectively. Therefore, roots provide a compensatory effect on geogrid strength, enhancing the long-term stability of ERSW. [ABSTRACT FROM AUTHOR]

Freeze-thaw (F-T) cycles are a major cause of pavement distress in seasonal frost regions, and the presence of fines in bases can accelerate the pavement degradation induced by cyclic freeze and thaw. Among countermeasures used to mitigate the F-T induced damages in pavements, geocell-reinforced bases can be an effective solution in mitigating F-T damage to cold region roads. However, there is almost no research dedicated to understanding the potential benefit of geocells and the underlying mechanisms in this regard. This study employed a custom-made model test device to investigate the F-T performance of geocell-reinforced sands considering different fines contents. The experimental results showed that the increase in fines content substantially increased the peak heave and thaw settlement and decreased the stiffness and ultimate bearing pressure. The application of geocells reduced the peak heave and thaw settlement by 11–18% and 22–35%, respectively, but this benefit was negligible at high kaolin content (12%). The use of geocells increased the stiffness and ultimate bearing pressure by about 43–90% and 41–73%, respectively, after five F-T cycles. The findings of this study are relevant to the design of geocell-reinforced bases under F-T cycles and advance the understanding of the underlying mechanisms. [ABSTRACT FROM AUTHOR]

The study presents a novel meshed horizontal–vertical (H–V) geogrid, offering promising advancements in geotechnical structure performance. The study pioneers a modeling approach for H–V geogrid foundation bearing capacity with discrete element method, expanding understanding and optimizing design strategy. By analyzing the granular displacement, contact force distribution, and vertical stress distribution within the foundation system, the study examines the impact of burial depth, vertical element height, and the number of vertical elements on H–V reinforced foundations. The findings suggest that employing a burial depth equivalent to the width of the footing enhances bearing capacity compared to conventional geogrid applications, with depths set at 0.4 times the width of the footing. This enhancement is attributed to forming a deeper slip surface in H–V systems. Moreover, raising vertical elements to 0.6 times the width of the footing enhances bearing capacity with minimal increase in geogrid usage, indicating a strategic approach to reinforcement. Increasing the number of vertical elements, particularly with three pairs, significantly enhances bearing capacity by reinforcing lateral restraint on the soil and promoting stress homogenization, thereby augmenting the "deep-footing" effect. The technical analysis underscores the efficacy of H–V geogrids in bolstering the bearing capacity of reinforced foundations, which is attributed to the robust grip and interlocking mechanism facilitated by these geogrids' vertical ribs and mesh structure, which augment lateral confinement and diminish horizontal soil displacement. [ABSTRACT FROM AUTHOR]

This experimental investigation describes an extensive series of reduced laboratory scale tests, conducted on circular and ring footing models rested on a geogrid reinforced cohesionless soil. The study examined the impact of several factors at different relative sand densities, such as the inner to the outer diameter ratio of the ring footing, the number of geogrid reinforcements, the depth of the initial reinforcement, and the vertical spacing between the geogrids, as well as the geogrid stiffness. The results indicated that the optimum diameter ratio of ring footings resting on loose or medium-dense cohesionless soil is 0.40 at which the maximum bearing capacity is reached, leading in a cost-effective design of the footings, while for the dense soil, a diameter ratio of 0.45 is the optimal ratio. Also, the results indicated that the optimum number of reinforcement layers which after the bearing capacity improvement can be considered negligible is three layers for the circular footing and four layers for the ring footing model. To achieve the maximum increase in bearing capacity, the study identifies optimal values for the depth of the first geogrid reinforcement layer and the vertical spacing between reinforcements, which apply to circular and ring footing. While the stiffness of the reinforcement has a significant effect on the bearing capacity, this effect is not proportional. [ABSTRACT FROM AUTHOR]

Building construction on slopes is inevitable, despite many limitations. On the other hand, due to the seismicity of Iran, calculating the seismic bearing capacity of foundations is more important. The construction along a slope has been observed to result in a reduction in the bearing capacity when compared to flat ground. To mitigate this decrease, various improvement techniques, such as the incorporation of reinforcements like geogrids, can be employed to partially offset the reduction in bearing capacity. The present study investigates the impact of ground slope (10 and 20 degrees) on the bearing capacity of granular soils with varying internal friction angles (25, 30, 35, 40, and 45 degrees) in both seismic and static conditions. This investigation employs the finite element limit analysis method and OptumG2 software to determine the upper and lower bounds of the bearing capacity. The findings indicate that the implementation of a horizontal earthquake coefficient of kh=0.1 leads to a reduction in the seismic bearing capacity of the foundation, ranging from 2 to 12 percent. The effective length of the geogrid is contingent upon the internal friction angle of the soil and varies within the range of 2B to 3B, where B represents the width of the foundation. Additionally, the study revealed that the optimal distance between the footing and the slope edge (X/B) is influenced by the internal friction angle, with a significantly bigger impact than the slope angle. In the current study, the optimal distance (X) was estimated to lie within the range of 2B to 4B for internal friction angles of 25, 30, and 35 degrees. Conversely, for internal friction angles of 40 and 45 degrees, the X value was assessed to be no less than 5B. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the sustainable use of recycled plastics, specifically polypropylene (PP) and high-density polyethylene (HDPE), in the manufacture of geogrids for geotechnical and civil engineering applications. Plastics were collected from a recycling center, specifically targeting containers used for food, cleaning products, and other domestic packaging items. These plastics were sorted according to the Möbius triangle classification system, with HDPE (#2) and PP (#5) being the primary categories of interest. The research methodologically evaluates the mechanical properties of PP/HDPE (0/100, 25/75, 50/50, 75/25 and 100/0% w/w) composites through tensile and flexural tests, exploring various compositions and configurations of geogrids. The results highlight the superiority of pure recycled HDPE processed into 1.3 mm thick laminated yarns and hot air welded for 20 to 30 s, exhibiting a deformation exceeding 60% in comparison to the PP/HDPE composites. Through SolidWorks® Simulation, it was shown that the adoption of a trigonal geogrid geometry optimizes force distribution and tensile strength, significantly improving slope stabilization efficiency. Based on the results obtained, a laboratory-scale prototype geogrid was developed using an extrusion process. The results underscore the importance of careful composite design and yarn configuration selection to achieve the desired mechanical properties and performance in geogrid applications. It emphasizes the potential of recycled plastics as a viable and environmentally friendly solution for stabilizing slopes, contributing to the reduction in plastic waste and promoting sustainable construction practices. [ABSTRACT FROM AUTHOR]

The bearing resistance provided by the geogrid's transverse ribs is a non-negligible aspect of the strength mechanism in mobilizing the geogrid–soil interface. Therefore, studying its influence on the response mechanism of geosynthetic-reinforced soil structures under cyclic loading is crucial. The stereoscopic geogrids were manufactured using 3D printing technology by quantitatively thickening the transverse ribs of planar geogrids. To investigate the cyclic hysteresis relationship and stress–dilatancy phase-transformation characteristics of the stereoscopic geogrid–coarse particle interface, cyclic direct shear tests were conducted. Additionally, a discrete element method (DEM) was employed to study the evolution of shear bands and fabric anisotropy at the interface under cyclic loading. The results of the study indicate that the stress–displacement phase angle of the stereoscopic geogrid in the horizontal direction of cyclic shear is smaller compared to the planar geogrid. Furthermore, thickening the transverse ribs decreases the stress–dilatancy phase-transformation angle of the interface. The thickness of the interface shear band in the stereoscopic geogrid is greater than that of the planar geogrid. Moreover, as the transverse-rib thickness increases, the principal direction of the average normal contact force and average tangential contact force under cyclic loading also increases. • Highlights the macroscopic and mesoscopic behavior of the 3D printed stereoscopic geogrid–coarse grain interface under cyclic shearing. • Comparing the interface stress–dilatancy phase-transformation angle of planar geogrids and stereoscopic geogrids. • The effect of transverse-rib thickness on the evolution of shear band and fabric anisotropy was quantified. [ABSTRACT FROM AUTHOR]