Geocell-reinforced Soil Research Articles

Dynamic analysis of high-rise residential structures through the cone method

In this article, to analyze the behavior of surface foundations based on reinforced soil, a simple physical method based on material resistance called (cone method) has been used. Which is used as an alternative to the exact solution methods that are based on the three-dimensional elastodynamic theory. The purpose of this research is to introduce a simple physical method and analytical tool to analyze the surface foundation based on geocell-reinforced soil. With the cone method, it is possible to examine the effects of layered soil. Obtaining the dynamic stiffness of the foundation based on reinforced soil using the cone method for the vertical degree of freedom and also investigating the effect of various parameters related to geocell reinforcement on the dynamic stiffness of the surface foundation are the goals of this research. In general, the longer the geocell cushion has, the smaller the holes, and the higher the modulus of elasticity, the better the results. By increasing the number of geocell layers, the amount of spring stiffness coefficient and damping coefficient and as a result the dynamic stiffness coefficient increases. On the other hand, the closer the geocell is placed to the soil surface, the higher the stiffness of the spring and the lower the damping coefficient. In general, among these two parameters related to dynamic stiffness, the role of the damping coefficient has been more prominent and decisive in the investigation of foundations based on reinforced soil. One of the most obvious characteristics of geosynthetic materials in the soil, regardless of the greater hardness it gives to the soil, is the damping percentage of its constituent materials.

Parameters affecting performance of fully instrumented model testing of strip footings on geocell-reinforced soils

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.

Geocells for Unpaved Roads: Analysis of Design Methods from the Literature

Most forest roads are unpaved, connecting rural and forest areas and enabling access for firefighting and commercial purposes. Low traffic levels lead to reduced functional demands, while rapid development of deformations results in frequent maintenance. Using geocells as reinforcements reduces deformations, minimizing maintenance needs. Herein, geocell-reinforced soil design methods were collected and categorized based on their result: increase in confining pressure; bearing capacity; height of the base layer. The goal was to compare methods reported in the literature, from a user perspective and within each category, using a base scenario. The methods were analysed to better understand their differences and application conditions. Methods that estimate the increase in confining pressure refer to static or cyclic loading, leading to results that are not directly comparable; often, the reinforcement contribution is represented by an apparent cohesion, with no physical meaning and misleading. Methods that estimate the increase in bearing capacity due to geocell consider its contribution differently (lateral resistance, vertical stress dispersion, and membrane effects) and distinct combinations. For geocell reinforcement, the membrane effect can be neglected. Methods that estimate the height of the base layer can be used directly for an expedite design of unpaved roads. When geocell reinforcement is adopted, the minimum height of the base layer should coincide with that of the geocell. Thus, while current methods contribute and support the design of unpaved roads, further work is essential to develop methods that are of simple and of expedite application for forest engineers, adaptable to local conditions and requirements.

Performance of eccentrically loaded strip footings on geocell-reinforced soil

In this pioneering study, the performance of an eccentrically loaded strip footing on geocell-reinforced sand was assessed with instrumented laboratory model tests in terms of pressure-settlement response, surface displacement profiles, failure mechanisms and ultimate bearing capacity considering load eccentricity, geocell height, geocell material stiffness and the relative density of the soil. The results indicated that strip footings on the geocell-reinforced sand outperformed those on unreinforced soils, with up to a 6.5-fold increase in the bearing capacity and significant improvements in the initial slope of the pressure-settlement curve. Furthermore, the strip footing under centric loading on the geocell-reinforced loose and dense sand exhibited either only punching or local shear failure while load eccentricity on the strip footing could lead to the shear failures including punching, local and general. In this research, both a design chart for predicting failure modes of geocell-reinforced strip footings and a new interpretation method to evaluate ultimate bearing capacity were proposed. Increasing the relative density of the soil and material stiffness enhanced the ultimate bearing capacity of geocell-reinforced strip footings under both centric and eccentric loading conditions, with stiffer materials resulting up to 25% increase. However, increased geocell height had no significant impact on bearing capacity.

Exploring the influence of size-related factors on geocell-reinforced soil response using coupled continuum-discontinuum analysis

Size-related factors, such as the dimensions and cell count of geocell, play a crucial role in determining the effectiveness of soil reinforcement. In this study, a 3D coupled framework that leverages the strengths of both continuum and discontinuum methods was developed to investigate the influence of pocket size and multi-cell configuration on geocell-reinforced soils. To unveil the impact of size-related factors on soil-geocell interactions, reinforced soils containing various geocell configurations (single large-sized cell, multiple small-sized cells), as well as geocell-free soils subjected to increasing levels of confining pressure were extensively examined. This thorough investigation aimed to establish correlations between macroscopic responses and underlying micromechanical mechanisms. Our findings revealed that the presence of the geocell not only enhances the densification of interparticle contacts and reduces the number of floating particles that contribute minimally to load support, but also facilitates the concentration of force chains within the geocell structure. This leads to an increase in elastic stiffness along the loading axis. These observations highlight that the geocell's confining mechanism enhances both the load-carrying capacity and the infill rigidity, thereby preventing lateral soil spreading. In essence, the geocell serves to increase the soil's ability to withstand load and maintain its structural integrity laterally.

Study on Mechanical Performance and Reinforcement Mechanisms of Geocell-Reinforced Soil

A concept for a reinforcement mechanism is presented and analyzed combined with test results to explain the reinforcement effect of a geocell. A series of pull-out and unconfined compression tests were carried out to investigate the effect of various parameters, including water content, compactness, and the number of geocell-reinforced layers, on the mechanical performance of geocell-reinforced soil. The results of the pull-out tests were mutually verified by the formulas for the reinforcement mechanism and demonstrate that the compactness and water content significantly affect the friction coefficient of the geocell–soil interface, which increases as compactness rises and water content falls. Compared with lowering the water content, improving compactness was better for enhancing the frictional properties of the geocell–soil interface; this had the highest increase, at 90%, as compactness rises from 92% to 94%. According to the unconfined compression test results, the unconfined compressive strength of geocell-reinforced soil is raised by higher compactness, more geocell-reinforced layers, and lower water content; this had the highest increase, at 93.1%, as the water content dropped to its optimum, from 19% to 15%. The compactness of filled soil dramatically influences the unconfined compressive strength of unreinforced specimens, which had an increase of 59.6% when compactness rose from 92% to 94%. However, this effect was weakened as more geocell was added to filled soil. As the number of geocell-reinforced layers rose from 0 to 1 under the compactness level of 92%, the increase of ultimate unconfined compressive strength reached 82.6%, higher than in other reinforcement layers.

Dominant elastoplastic behavior of geocell-reinforced sand subjected to cyclic loading under large-scale triaxial tests

The beneficial effects of geocells on improving the soils' characteristics have always drawn researchers' attention. However, due to the geocell's large scale, more accurate analyses, such as large-scale cyclic laboratory tests, are still needed to determine the soil-geocell system's actual mechanism. In the present research, a series of large-scale triaxial tests are carried out on poorly graded sand samples with 30 cm diameter and 60 cm height reinforced by geocell with heights of 0.6, 1.0, and 1.4 of the pocket diameter and placement depths of 0.05, 0.15, 0.25, and 0.35 of the samples' height under static and cyclic loading conditions. Contrary to common opinion, the results obtained for unreinforced sands showed that the maximum bulge, instead of the middle, occurred at 0.25 of the sample's height from the top surface. Changing the bulging from the middle to the upper part reflects the role of the direction of stress applied and the accumulation of the deformation due to plastic behavior near the load position. On the one hand, the results of static tests revealed that placing geocell at this depth delivers the best performance in controlling the bulging and reducing settlement values due to the predominant lateral support to the sand particles, reducing the localized stress concentrations, increasing internal friction and interlocking, and reducing the likelihood of shear failure. On the other hand, the geocell with moderate height had higher wall rigidity and stability against deformations compared to the geocell with lower and higher height values due to higher soil confinement potential and more resistance against buckling, respectively. Cyclic loading was also performed on geocell-reinforced soils under 110 cycles with cumulative strains ranging from 0.13 to 0.155 %. The cumulative strains for the unreinforced and reinforced soils were 0.196 % and in the range of 0.130–0.154 %, respectively. The best geocell placement depth under cyclic loading mode was at 0.05 of the sample's height, which had a cumulative strain of 0.13 % in 110 cycles and reduced the cumulative strain by about 34 % compared to the unreinforced sample. The presence of geocell in the soil generally led to an increase in the shear modulus and a decrease in the slope of the damping ratio. Further, the shear modulus was reduced by increasing the geocell placement depth.

Effect of the Slit on the Mechanical Tearing Behavior of High-Density Polyethylene and Polyester Geocell Strips

Geocells are widely applied in numerous infrastructure constructions, like heavy-haul railways and ports. The mechanical tearing behavior of a geocell strip is crucial to the stability of the geocell-reinforced soil structures. At present, extensive studies have been conducted on the tensile characteristics of geocell strips, while limited research has been performed to investigate the post-damage mechanical tearing behavior of geocell strips. Meanwhile, there is also a lack of research on the comparison of performance of strips before and after damage. In this paper, a series of trapezoidal tearing tests were performed on high-density polyethylene (HDPE) and polyester (PET) geocell strips. The tearing test results and failure mode of trapezoidal specimens with a slit were investigated, and the effect of the slit on the strength and deformation characteristics of the specimen were discussed by introducing the “damage ratio of tearing force (RTF)” and “damage ratio of tearing displacement (RTD)”. In addition, the mechanical tearing behavior of HDPE and PET trapezoidal specimens was also compared. The test results indicated that the failure mode of HDPE and PET specimens subjected to tearing force was ductile and brittle failure. The strength and deformation characteristics of post-damage HDPE and PET trapezoidal specimens decreased. The slit had a significant impact on the tearing displacement of HDPE and PET specimens, especially the post-peak tearing displacement. The post-peak tearing displacement of HDPE was 10.99 times that of PET. The peak tearing force of the HDPE specimen without the slit was about 1.61 times that of specimen with the slit. Before local tearing, the peak tearing force of the PET specimen without the slit was about 3.27 times that of the specimen with the slit. The strength damage to the HDPE and PET geocell strips caused by the slit was 38.0%, and 69.46%. The impact of the slit on the tearing force of the PET specimen was greater than that of the HDPE, and was 1.82 times for the HDPE. This study can enhance our understanding of the mechanical tearing behavior of the geocell strip after damage and develop effective mitigation measures.

Geomechanical performances of geocell reinforced retaining wall backfilled with magnesia-based cement stabilized marine fill

Cement-stabilized soil retaining wall structures are becoming increasingly popular for high-speed railway lines. However, the widely used Portland cement is heavily associated with carbon dioxide (CO2) emissions. Additionally, the rising cost and scarcity of sand traditionally used as fill material is becoming a concern. Besides, the geomechanical performances of the cement-stabilized soil retaining walls using three-dimensional (3-D) finite element method (FEM) numerical analysis have seldom been investigated. To address these issues, this study investigates the geomechanical performances of geocell-reinforced soil (GRS) backfilled with magnesia-based cement-stabilized marine fill using the nonlinear stress-strain relationship and 3-D FEM models as an alternative to the traditional earth GRS walls. The study finds satisfactory results regarding stability, deformation, and settlement. Only nominal facing reinforcements may be required as the magnesia cement mechanically stabilizes the fill. Moreover, the strength and stiffness properties improve with increased curing duration. The safety factors and observed displacements were within acceptable limits. However, the critical region for the cement-stabilized marine fill GRS wall showing a rupture zone was identified at the toe of the structure. Finally, the study developed a load-displacement model for settlement predictions and uncertainty interpretations, and explained the strength development and deformation mechanisms. The results suggest that cement-stabilized soil retaining walls using magnesia-based cement could be a viable alternative to traditional earth GRS walls, while mitigating environmental concerns and reducing costs.

Time-dependent study of load transfer mechanism in geocell reinforced soil bed

Geocell-reinforced embankments are commonly subject to rail or road traffic which comprises repetitive loads. However, the existing equations for the analysis and design of geocell-reinforced systems are based on performance under static loads. Hence, it is imperative to study the performance of geocell-reinforced embankments under repetitive loads. The study addresses the shortage of time-dependent studies on geocell-reinforced systems by analyzing the performance of geocell-reinforced embankments under repetitive loads over time. The actual curvature of honeycomb-shaped pockets is carefully modeled for accurate analysis of the load transfer mechanism of geocell-reinforced soil. The study analyses two different geocell configurations that are conventionally adopted in practice. In the first case, the geocell platform is placed at the embankment base and restrained within the toe of the embankment. In the second case, the platform is extended on both sides to serve as a working platform. The study aims to assess the effect of the configuration of geocell reinforcement under different types of loading. The time-dependent response of the embankment over the geocell platform is then analyzed for static and repetitive loads to assess the performance of geocell-supported embankments under different loading applications. The lateral deformation at the toe, stress on the subgrade, and heave characteristics are analyzed for time. It is observed that the presence of geocell at the embankment base not only reduces the stress transferred to the subgrade but also mitigates differential settlement over time. The difference in reinforcing effect under static and repetitive loads is notable in the case of surface heave reduction. Both configurations reduce stress on the subgrade. However, for a significant reduction in surface heave, it is recommended to place the geocell mat as a working platform extending beyond the embankment toe on both sides.

Experimental and intelligent modelling for predicting the amplitude of footing resting on geocell-reinforced soil bed under vibratory load

The reliable estimation of displacement amplitude is the prime factor for the design of geo-structures supporting the vibration loads. Currently, very subtle knowledge is available to compute the displacement amplitude of footing resting on the geocell-reinforced bed subjected to vibration loading. The advent of artificial intelligence modelling has antiquated many traditional approaches. Thus, in the present study, a novel hybrid paradigm has been developed by combining the artificial neural network (ANN) with dragonfly optimizer (DFO), abbreviated as ANN-DFO. To train and test the model, the reliable database was developed by conducting extensive field vibration tests. To establish the specific prediction target for the proposed model, displacement amplitude (da) was considered as an output index. A combination of parameters involving properties of foundation bed, geocell reinforcement, and dynamic excitation has been considered as input variables. Along with the standalone ANN model, the predictive veracity of the ANN-DFO was also compared with three other robust machine learning models, namely, Gaussian process regression (GPR), random forest (RF), and M−5 rules. Primarily, the forecasting ability of the developed models was assessed based on rigorous statistical criteria and a multi-criteria approach. Moreover, the model is also validated against the entirely new independent data which is not part of the original dataset. From the results, ANN-DFO model has shown a superior performance in predicting the displacement amplitude of footing resting on geocell-reinforced beds as compared to the other benchmark models. Finally, the strength of input variables on the estimation of displacement amplitude was highlighted using the sensitivity analysis.

Proposed novel bond-slip model for geocell reinforcement under pull-out loading condition

An analysis of a novel bond-slip model for geocell reinforcement in cohesionless soils was established in terms of bond stresses and displacements to evaluate the behaviour of geocell-reinforced soil structures. In this study, the bond-slip behaviour of geocell-reinforced cohesionless soils under different normal and interfacial shear stresses was investigated using a total of 55 pull-out tests on geocell reinforcements of different size and stiffness. The results obtained for load–displacement behaviour of the 55 pull-out tests on the geocell reinforcements in cohesionless soil were converted to bond stress–displacement graphs. Overall, it was found that the bond stress–displacement parameters depend significantly on the size and stiffness of the geocell reinforcement and the applied vertical stress.

Discussion of “EPS Geofoam Pavement Foundations Overlaid by Geocell-Reinforced Soil under Static Loading: Large-Scale Tests and Numerical Modeling’’ S. N. Moghaddas Tafreshi, S. M. A. Ghotbi Siabil, and Mehran Azizian

Discussion of “EPS Geofoam Pavement Foundations Overlaid by Geocell-Reinforced Soil under Static Loading: Large-Scale Tests and Numerical Modeling’’ S. N. Moghaddas Tafreshi, S. M. A. Ghotbi Siabil, and Mehran Azizian

Behavior of Geocell-Reinforced Soil Abutment Wall: A Physical Modeling

Behavior of Geocell-Reinforced Soil Abutment Wall: A Physical Modeling

Performance of Genetic Programming and Multivariate Adaptive Regression Spline Models to Predict Vibration Response of Geocell Reinforced Soil Bed: A Comparative Study

Performance of Genetic Programming and Multivariate Adaptive Regression Spline Models to Predict Vibration Response of Geocell Reinforced Soil Bed: A Comparative Study

A Review on the Design, Applications and Numerical Modeling of Geocell Reinforced Soil

For improving the stability and load carrying capacity of weak subgrade, strengthening methods are to be followed in the field. Among the various approaches, geocells have been identified as an effective soil reinforcement technique for improving soft subgrade behaviour. The three-dimensional honeycomb structure of geocell offers more lateral confinement to the infill soil resulting in improved load carrying capacity. This led to the widespread use of geocells for different geotechnical applications like pavements, foundations, embankments, slope protection, erosion control etc. Many researchers in the past have confirmed the suitability of geocell reinforcement through their experimental, numerical and field studies. In this paper, a comprehensive review of the reinforcement mechanisms, design aspect and numerical modelling techniques of geocell reinforced soil is provided. In addition, this paper highlights the various field application scenarios where different types of geocells have been used and explores the research challenges and scope for further research in this field.

EPS Geofoam Pavement Foundations Overlaid by Geocell-Reinforced Soil under Static Loading: Large-Scale Tests and Numerical Modeling

AbstractPavement foundations supported on expanded polystyrene (EPS) geofoam blocks are vulnerable to excessive deformation or even failure owing to truck passage during construction. To investigat...

Model tests of freeze-thaw behavior of geocell-reinforced soils

Freeze-thaw cycles are a major cause for destabilizing pavements in cold regions. Among countermeasures for freeze-thaw damages, use of geocells to reinforce pavement bases is an effective solution in practice. However, as opposed to widespread applications, research concerning freeze-thaw behavior of geocell-reinforced bases is limited, probably due to a lack of proper devices for conducting experimental tests. This paper presents a new model-test device capable of performing both freeze-thaw tests and plate loading tests on geocell-reinforced soils. A thermodynamic numerical model was developed to assist with the design of freeze-thaw component of the device, while the design of plate loading component was developed by referring to features of existing devices. Eleven tests were run on geocell-reinforced and unreinforced sands to confirm the effectiveness of the proposed device. The test results showed the device successfully provided vertical heat transfer in sands during freeze and thaw. After five freeze-thaw cycles, geocells reduced peak frost heave and thaw settlement of sands by 18% and 34%, respectively, and increased the stiffness and bearing capacity by 40% and 253%, respectively. It was found a temperature drop occurred at the interface between cooling plate and sands, which was due to the existence of thermal contact resistance.

Comparative Study for Performance of Soil Bed Reinforced with Jute and Sisal Geocells as Alternatives to HDPE Geocells

This paper presents the performance of soil bed reinforced with jute and sisal geocells compared to HDPE geocells. The bearing pressure–settlement behaviour of the soil bed reinforced with natural geocells, soil bed reinforced with HDPE geocells and of unreinforced soil bed are discussed. The soil bed reinforced with jute cell and sisal cell showed a uniform increase in the settlement with increase in the applied pressure. The soil reinforced with HDPE geocell, however, showed a sudden rise in the settlement at higher pressure. Sisal mat used for developing the geocell was found to have greater tensile strength, followed by jute mat over HDPE material. Soil reinforced with sisal cells could bear larger stresses at lower strain compared to HDPE geocell. Analytical studies on jute and sisal geocells also were carried out considering the load transfer mechanism of geocell-reinforced soil.

Stress-dependent method for calculating the modulus improvement factor in geocell-reinforced soil layers

This paper presents an analytical method for determining the modulus improvement factor (MIF) in geocell-reinforced soil layers. Using a modified version of the hyperbolic soil model as a constitutive model, the method is developed based on the soil-reinforcement interaction relating nonlinear elastic soil behavior to the linear elastic response of the reinforcement. The proposed method, in an original way, explicitly takes into account the geometry of the geocell pocket, effects of soil and geocell-reinforcement stiffness, compaction-induced stresses, soil strength and strain compatibility. The method can be used both analytically and using simple and presented non-dimensional charts. Parametric analyses show that the reinforcement, soil relation and the stresses induced during the compaction procedure are the major factors influencing MIF. An evaluation using data from several laboratory, full-scale and field experiments in works is presented showing good predictive capability of proposed method. An application procedure for calculating MIF is presented.