Search Results (236)

Expansive soil slopes are highly susceptible to rainfall-induced shallow failures due to cyclic swelling–shrinkage behavior governed by matric suction variation. This study proposes a composite frame–geosynthetic system (CFGS), comprising a rigid frame integrated with high-performance turf reinforcement mats (HPTRMs), for expansive soil slope protection. The performance of the CFGS was evaluated through geometrically scaled, materially representative physical model tests under repeated wetting–drying cycles and further examined using coupled hydro-mechanical numerical simulations in COMSOL Multiphysics. A bare slope and an HPTRM-protected slope were used for comparison. Under identical laboratory conditions, CFGS reduced cumulative erosion to approximately 13% of that of the bare slope. It also moderated the internal hydraulic response, reducing pore-water pressure fluctuation by approximately 26%, and restrained swelling–shrinkage deformation, with an average deformation attenuation of up to 61%. The numerical simulations showed consistent response trends with the physical model tests, supporting the proposed mechanism of hydraulic regulation, deformation restraint, and stress redistribution. Overall, the results demonstrate the comparative effectiveness of CFGS in mitigating wetting–drying-induced deterioration of expansive soil slopes. Full article

The application of carbon-fiber-based geogrids in asphalt pavements is still in the nascent phase of research in China. Compared with glass fiber, carbon fiber undergoes processes such as electrochemical surface oxidation and coating with a sizing agent (polyurethane-based) to enhance its bond strength with bitumen or concrete, and to improve its wear resistance and suitability for construction. Utilizing a suite of laboratory tests including rutting tests, low-temperature flexural failure tests, and Leutner shear tests, this study researches the impacts of surface combined body type and geogrid type on the high- and low-temperature performance characteristics and interlayer shear performance of asphalt pavement structures. The results demonstrate that carbon-fiber-based geogrid reinforcement improves the rutting and low-temperature cracking resistance of asphalt surface combined bodies, with the carbon fiber geogrid (CCF) variant exhibiting superior performance to the carbon/glass fiber composite geogrid (GCF) in both aspects. Relative to GCF reinforcement, CCF reinforcement achieves increases of 12.80–13.74%, 4.53%, and 37.47% in dynamic stability, flexural tensile strength, and flexural tensile strength enhancement rate, respectively, indicating that the polymer coating process enhances the reinforcement effect of carbon-fiber-based geogrids. Carbon-fiber-based geogrid reinforcement compromises the interlayer shear performance of asphalt pavement composites; nevertheless, CCF reinforcement delivers 13.94–28.14% better interlayer shear performance than GCF reinforcement. This indicates that the polymer coating process enhances the shear resistance at the interface of carbon-fiber-based geogrids. Surface combined body type is a key factor governing the high- and low-temperature performance and interlayer shear behavior of reinforced surface combined bodies. The dynamic stability, maximum flexural-tensile strain, and interlayer shear strength of the AC-20/AC-25 are all superior to those of the AC-13/AC-20, with respective increases of 40.25%, 27.58%, and 8.5–25.6%. The test results may provide meaningful insights into the performance behavior of geogrid-reinforced asphalt pavements. Full article

Geosynthetics-reinforced soil technology represents an innovative reinforcement method for calcareous sand foundations and revetment engineering in coral reef areas. The interaction response at the reinforced soil interface directly influences the safety and stability of reinforced soil structures. However, research on the interaction mechanisms between geosynthetics and calcareous sand interfaces remains insufficient. Therefore, this paper investigates the effects of different normal stresses and various interface types on the shear characteristics of the geosynthetics–calcareous sand interface through a series of large-scale monotonic direct shear tests. By integrating statistical damage theory and accounting for the influence of residual strength, we establish the constitutive relation for interface damage. The results indicate that the shear stress–displacement curves for both the geosynthetics–calcareous sand interface and the unreinforced calcareous sand exhibit softening behavior. Furthermore, the relationship between the interface shear modulus and horizontal displacement for the geogrid–calcareous sand and unreinforced calcareous sand adheres to a power function model, while the relationship for the geotextile–calcareous sand follows a logarithmic function model. In the structural design of geosynthetics-reinforced calcareous sand, it is crucial to consider the influence of residual shear strength on structural stability. This study proposes a statistical damage constitutive model that accounts for the strain-softening characteristics of the geosynthetics–calcareous sand interface, while also considering the impact of residual strength. The findings provide a theoretical basis for the stability analysis of geosynthetics-reinforced calcareous sand structures in coral reefs with significant engineering implications for island reef construction, coastal development, and bank slope protection projects. Full article

This study re-examines two geologically and geotechnically similar geosynthetic-reinforced soil walls with modular block facings (GRS-MBs) that exhibited markedly different seismic performances during the 1999 Chi-Chi earthquake (M_L = 7.3). Integrating a multi-wedge failure mechanism that captures soil–facing–reinforcement interactions with a nonlinear hyperbolic soil model representing shear stress–displacement behavior along the slip surface, the Force–equilibrium-based Finite Displacement Method (FFDM) provides consistent and robust displacement evaluations over a wide range of input seismic inertial forces. A systematic sensitivity investigation confirms that the FFDM framework responds to parameter variations in a physically meaningful manner, and that displacement predictions remain stable with respect to reasonable uncertainties in soil, reinforcement, and facing properties. The analysis clarifies why two similar GRS-MBs responded so differently during strong shaking and demonstrates the broader applicability of FFDM for displacement-based seismic assessment, including under shaking levels (e.g., k_h ≈ 0.3) that would drive conventional limit–equilibrium calculations to F_s < 1.0, a physically impossible state requiring shear resistance greater than the soil’s ultimate strength. A comparative evaluation of seismic displacement predictions using the Newmark method and FFDM shows that FFDM successfully generates displacement-based seismic resisting curves and reproduces field-observed displacements. In contrast, the Newmark method yields order-of-magnitude variability in predicted movements and may be unsuitable for displacement-sensitive engineered slopes where deformations on the order of several 10⁻³–10⁻² m are practically significant. For interaction-rich GRS-MBs with high values of k_hc, beyond the predictive capability of Newmark’s equation, FFDM offers a practical and physically grounded tool for seismic displacement assessment of reinforced soil structures. Full article

Pile-supported geosynthetic-reinforced embankments, as effective foundation improvements, are being used increasingly often in the construction of highway and railway engineering at present. The geosynthetic-reinforced load transfer platform in the horizontal direction was simulated to the thin plate, and then the differential equation of the curved surface and the nonlinear foundation model were used to solve the analytical expression of the post-construction settlement of the reinforced area, and the engineering example was used to verify it. Furthermore, a finite element model was developed to simulate the settlement. The analysis utilized a static general step and incorporated a linear elastic–perfectly plastic model with the Mohr–Coulomb failure criterion. The numerical result of 19.7 mm was consistent with the theoretical prediction of 20.1 mm, demonstrating a mere 2.0% relative error and substantiating the validity and accuracy of the theoretical model. The analysis examined how bending stiffness, the subgrade reaction coefficient, pile spacing, and embankment height affect post-construction settlement. The results demonstrate that the settlement increases with larger pile spacings or lower values of the subgrade reaction coefficient and bending stiffness. Notably, the settlement increases with embankment height only until a critical height—calculated from the bearing capacity of the inter-pile soil—is exceeded. Based on this, it was found that the subgrade reaction coefficient was identified as the most influential parameter, followed by pile spacing and then bending stiffness. These findings lead to practical recommendations for engineering practice. Full article

Localized subsidence remediation in narrow working areas is often constrained by limited reinforcement width and anchorage length. This study investigates the load-transfer and deformation behaviour of multi-layer geosynthetic reinforcement under such conditions through 1:5 scaled trapdoor tests and PFC2D simulations. A three-layer geotextile system was tested by varying anchorage length and interlayer spacing, and a soil arching load-transfer ratio, η, was introduced to quantify the contribution of soil arching. The results show that increasing anchorage length from 0.5B to B increased η from 74.82% to 86.51%, whereas a further increase to 1.5B raised η only slightly to 89.02%. Over the same range, surface settlement and the midspan deflection of the lowest reinforcement decreased by 26.84% and 16.46% from 0.5B to B, but only by a further 1.55% and 2.53% from B to 1.5B. At L = B, η reached 61.89%, 86.51%, and 78.75% for s = 0.3B, 0.2B, and 0.1B, respectively, indicating that the intermediate spacing was most favourable for soil arching load-transfer. The DEM results further showed diminishing returns with increasing layer number, with the three-layer configuration achieving about 95% of the five-layer performance. Overall, high and stable load-transfer performance was obtained at L/B = 1.0–1.25 and s/B = 0.15–0.2. Full article

High-density polyethylene (HDPE) geomembranes (GMs) in landfill liners experience UV exposure during installation. While tensile strength deterioration after UV aging is known, changes in interfacial shear properties are rarely reported. This study investigates the evolution of interfacial shear behavior at the GM/sand interface by subjecting GM specimens to varying durations of indoor UV aging followed by direct shear tests. Underlying mechanisms were explored through tensile strength, melt flow index, crystallinity, and oxidation induction time (OIT) measurements. Results show that displacement required to reach peak shear strength for smooth geomembrane (GMS)/sand interface decreased with aging time (49.0–70.1% reduction), while no clear trend emerged for textured geomembrane (GMX)/sand interface. Following 80 days of UV exposure, the GMS/sand interfacial shear strength declined, with the peak friction angle dropping 20.6% from 26.2° to 20.8°. For the GMX/sand interface, the peak friction angle dropped to its lowest value of 31.2° after 40 days of exposure (from 34.3°), and then exhibited an increase with further UV aging. The large displacement shear strength followed a trend similar to that of the peak strength. Among the other tested indicators, the variation pattern of OIT with UV exposure exhibited the best correlation with the GMS/sand interface shear strength. Full article

Shaking table testing has become a fundamental experimental approach in geotechnical earthquake engineering for investigating seismic soil–structure interaction. Although numerous studies have examined the dynamic behavior of reinforced retaining walls and soil slopes, the existing body of literature remains fragmented, with significant variations in scaling approaches, boundary conditions, input motions, and instrumentation methods. To date, no comprehensive review has critically synthesized these studies to identify consistent behavioral trends and methodological limitations. This paper presents a systematic and critical review of shaking table investigations of geosynthetic-reinforced retaining walls and clayey soil slopes. The review consolidates global experimental findings to evaluate how key parameters—including excitation characteristics, soil density, surcharge loading, reinforcement configuration, and boundary conditions—influence displacement patterns and acceleration amplification. Recurring response mechanisms are identified, such as elevation-dependent amplification, nonlinear frequency effects, and the confinement benefits of reinforcement and surcharge. The review further examines discrepancies among studies and between experimental and numerical results, highlighting challenges related to similitude requirements, boundary effects, and signal fidelity By synthesizing dispersed experimental evidence and critically evaluating methodological variations, this review provides a clearer understanding of seismic response mechanisms and offers guidance for improving experimental consistency and promoting future standardization in shaking table testing. Full article

Geogrid reinforcement is an effective subgrade treatment technique that plays a critical role in improving structural stability and controlling deformation in highway widening projects. In this study, the reinforcement mechanisms and performance of geosynthetic-reinforced embankments with varying heights were systematically investigated using finite element simulations conducted in ABAQUS. An improved nonlinear soil-reinforcement interface model was incorporated and implemented through a user-defined FRIC subroutine, allowing for a more accurate representation of nonlinear shear behavior at the soil-geosynthetic interface and providing deeper insight into the reinforcement mechanism within the subgrade structure. The results indicate that bottom-layer reinforcement offers the most significant improvement in overall stability and deformation control. Although multi-layer reinforcement configurations (top-middle-bottom or middle-bottom) further enhance performance, their additional benefits are limited for low embankments. Tensile strain within the reinforcement decreases with increasing distance from the existing slope, with the bottom geosynthetic layer exhibiting the most uniform strain distribution and playing a dominant role in settlement control. Considering both structural performance and reinforcement efficiency, a “sparse-top and dense-bottom” reinforcement configuration is recommended. Specifically, single bottom-layer reinforcement is suitable for embankments ≤ 3 m in height, double-layer reinforcement (bottom-middle) is optimal for embankments 3–7 m high, and triple-layer reinforcement (top-middle-bottom) is recommended for embankments exceeding 7 m, in combination with ground improvement, compaction control, and slope protection measures to ensure overall stability. The reinforcement optimization strategy proposed in this study provides a scientific basis and practical guidance for the structural design and performance enhancement of highway widening projects. Full article

Climate-driven extremes in temperature and precipitation are increasingly threatening the stability and serviceability of slopes, embankments, levees, transportation corridors, and other earthen infrastructures founded on expansive and problematic soils. Conventional stabilization strategies, which often treat reinforcement and drainage as separate design elements, struggle to cope with cyclic wetting-drying, freeze-thaw, and prolonged rainfall events that drive desiccation cracking, loss of matric suction, elevated pore-water pressures, and progressive strength degradation. This paper presents a state-of-the-art review of geosynthetic-reinforced slopes with particular emphasis on geogrid geotextile composite systems and their performance under high-temperature, high-rainfall, and low-temperature environments. We first summarize the fundamentals of geosynthetic types, functions, and material properties, then examine how thermal and hydrological processes such as creep, oxidation, frost heave, infiltration, suction loss, and pore-pressure build-up govern the performance of geosynthetic-reinforced soil (GRS) systems. Next, we synthesize recent advances in composite geosynthetics that integrate reinforcement, filtration, separation, and drainage, highlighting laboratory studies, centrifuge modeling, numerical analyses, and field case histories for mechanically stabilized earth walls, pavements, railway embankments, levee systems, and rainfall-induced and expansive soil slopes. Across these applications, geogrid geotextile composites consistently improve hydraulic control, maintain effective stress, and enhance factors of safety under extreme climatic loading. The review concludes by identifying critical research gaps, including coupled thermo-hydro-mechanical characterization, performance-based design approaches, and climate-resilient guidelines for geosynthetic selection and detailing. These findings underscore the potential of composite geosynthetics to enable more sustainable and resilient slope and earthwork infrastructure in a changing climate. Full article

The long-term creep performance of geosynthetics is crucial for the safe design of reinforced-soil structures. Previous studies have not sufficiently clarified the long-term creep behavior of high-density polyethylene (HDPE) geogrids or the influence of different failure criteria. Therefore, further research is needed to validate creep reduction factors’ (RF_CR) estimation and the applicability of the stepped isothermal method (SIM). In this study, the creep behavior of HDPE geogrids was examined using both conventional creep tests and SIM, conducted in accordance with ISO 13431 and ASTM D6992. Master curves were generated under load levels representing 40–60% of the ultimate tensile strength. The SIM results matched with the conventional tests in the early stage but exhibited higher creep strains beyond 1000 h, primarily due to the thermal sensitivity of HDPE. RF_CR values were determined using two design criteria, namely, 20% creep strain and creep rupture. For a 100-year design life, the RF_CR values based on a 20% creep strain were determined to be 3.04 and 2.43 based on the combined data and block-shift analysis, respectively, whereas the rupture criterion yielded a lower value of 2.30. These findings demonstrate that the 20% strain limit provides a more conservative and reliable criterion for estimating the long-term design strength. This study confirms the applicability of SIM for accelerated creep evaluation and provides practical guidance for the selection of RF_CR values in reinforced-soil design. Full article

In order to investigate the effects of gravel particle size and geogrid aperture on the bearing performance of geosynthetic-encased stone columns, a discrete–continuum coupled numerical model was established based on laboratory test results, and a series of numerical simulations were conducted. The results indicate that, under the same loading level, the maximum lateral bulging of geosynthetic-encased stone columns increases with increasing geogrid aperture and decreases with increasing gravel particle size. The distance between the location of maximum lateral bulging and the pile-top decreases as the aperture increases, whereas it increases with increasing particle size. The bearing performance of geosynthetic-encased stone columns shows a positive correlation with gravel particle size and a negative correlation with geogrid aperture. The influence of particle size on bearing performance becomes insignificant when d₅₀ exceeds 40 mm. When the particle size is smaller than the geogrid aperture, contact between the gravel and the geogrid is established but remains insufficient, leading to separation as the load increases. In contrast, when the particle size is larger than the aperture, the effect of particle size on bearing performance is much more pronounced than that of aperture. Therefore, the use of gravel with a particle size slightly larger than the geogrid aperture is recommended in practical engineering applications. Full article

Seasonal groundwater rise of 2.5–3.0 m leads to full saturation of the lakeside slope of the railway embankment, significantly reducing the strength of clayey–sandy loam layers. Laboratory shear tests showed that saturation decreases the internal friction angle from 24–26° to 16–19°, while effective cohesion drops from 12–18 kPa to 0–3 kPa, identifying the 3–6 m depth interval as the critical weak zone. These parameters were incorporated into PLAXIS 2D/3D hydro-mechanical models to assess the embankment behaviour under three scenarios: natural conditions, high water level, and reinforced configuration. Under elevated water levels, lateral displacement toward the lakeside increased to 0.16–0.21 m, and the plastic strain zone expanded by a factor of 2.4, reducing the safety factor from FS ≈ 1.32 to below 1.10. The proposed stabilization system—replacement of a 1.5 m weak layer, installation of geotextile reinforcement, and application of a bituminous waterproofing layer—substantially improved stability, reducing maximum lateral displacement to 0.12 m (≈43% reduction) and restoring the safety factor to FS = 1.25–1.40. The results demonstrate that low-cost geosynthetic barriers provide an effective and practical engineering solution for maintaining the long-term stability of railway embankments exposed to seasonal inundation. Full article

The paper presents a recently developed rigid-wall diffusion cell and the experimental setup that allows the determination of the coefficient ω, which quantifies the degree of solute restriction in clays or GCLs that exhibit semi-permeable membrane behaviour. In addition, the apparatus allows the monitoring of the total vertical stress acting on the specimen during a chemico-osmotic diffusion test while keeping the vertical deformations at a negligible level (<1%). This improvement of the traditional testing approach allows for the determination of the chemical-osmotic efficiency coefficient, ω, and of the swelling coefficient $\overline{\omega }$, the main parameters that characterize the chemico-osmotic behaviour of clays and GCLs on the same specimen. The paper also reports on the results of some tests carried out on conventional and enhanced GCLs, with the main purpose of comparing the results obtained by means of the new testing apparatus with literature data. A first application of an advanced existing theoretical model for the description of chemical-osmotic phenomena to the results obtained is also illustrated. Full article

The use of geosynthetics in reinforced soil structures (RSSs) requires the experimental and numerical modelling of the soil–geosynthetic interaction to support the design and analysis and deepen the knowledge of RSS systems. Direct shear testing has served as a fundamental laboratory choice for soil–geosynthetic interface testing, with the benefits being its availability, simplicity, and straightforward shear strength acquisition. This review paper pays attention to the direct shear testing and modelling of soil–geosynthetic interfaces. A brief laboratory interface experiment overview is presented, summarising the adopted soil–geosynthetic types, as well as the influences of various factors regarding soil–geosynthetic properties and loading/environmental conditions. Development of the finite element method to model interfaces is introduced, concentrating on the commonly adopted zero-thickness element, the thin-layer element, and continuum elements. As a result, emphasis is given to the comparison of the three element methodologies for the analysis of their advantages and limitations in accuracy, stability, and applicability for interface modelling. Based on the retrospective analysis, a summary and visions for the research progress of soil–geosynthetic interface testing and modelling are proposed to provide suggestions for future research topics. Full article