Performance Of Embankment Research Articles

Enhancing the seismic performance of highway embankments on soft soils: a comparative study of conventional and T-shaped deep cement mixing columns

Enhancing the seismic performance of highway embankments on soft soils: a comparative study of conventional and T-shaped deep cement mixing columns

Performance of unreinforced and geogrid-reinforced pile-supported embankments under localized surface loading: Analytical investigation

An analytical solution is proposed to identify the performance of unreinforced and geogrid-reinforcement pile-supported embankments under localized surface loading at working stress conditions based on the total efficacy and efficacy induced by soil arching alone, average strain of geogrid reinforcement, and average settlement of subsoil. This solution considered interactively soil arching within the embankment fill, the load-deflection behavior of geogrid reinforcement (if existed), and subsoil settlement. Specifically, the soil arching consisted of a structural arch with different stress states (evaluated by the elastoplastic state coefficient K) and a frictional arch. The load-deflection behavior of geogrid reinforcement was modeled by a membrane, with due consideration of the skin friction between the geogrid and soil. The subsoil was idealized as a one-dimensional compression model. The effectiveness of the proposed solution was verified by comparisons with results from the collected literature. It is shown that geogrid reinforcement improved the performance of embankments with low subsoil stiffness significantly more than that of those with high stiffness subsoil. A high tensile stiffness geogrid was found to be inefficient because its contribution to reducing the subsoil settlement and enhancing the load transfer efficacy was minimal. This paper provides a significant reference for optimizing these embankment design.

A frictional arch model for pile-cap-beam-supported embankment

The pile-cap-beam-supported (PCBS) system can strength the soil arching effect of embankment, increase the lateral stiffness, bending resistance and vertical bearing capacity of the rigid pile, however there is no frictional soil arch model of PCBS embankment. In this paper, first a frictional arch model for PCBS embankment modified from Russell’s frictional arching model was proposed. The proposed model in this paper considers the algorithm of lateral pressure coefficient k and a changing critical height of soil arch. In this new method, the influence of pile spacing, filling properties, height and pile spacing on critical height soil arch was comprehensively considered. Second, a series of numerical cases were performed to verify the effectiveness of the proposed model and study the arching effect of PCBS embankment. By comparing the vertical stress and settlement between the theoretical and simulation results, the rationality of the proposed method to estimate the stress and critical height of arch was validated. The effectiveness of the proposed method was further validated by comparing loading efficacy to a reported case. Last, the stress and deformation of PCBS and pile-cap-supported (PCS) embankment were analyzed and the superiority of PCBS system in improving the performance of embankment was observed finally.

Performance and reinforcement of air-cooled embankments traversing degrading permafrost of the Qinghai-Tibet Plateau

The reliable operation of railway embankments traversing degrading permafrost regions is challenged by climate warming. This study examines performances of four main types of railway embankments on the Qinghai-Tibet Plateau in thermally stabilizing permafrost foundation over warm permafrost using numerical modelling and 10-year monitoring data. Then, a reinforcement measure that combines a thermal conductivity variable system (TCVS) was designed to improve the cooling capacity of the crushed-rock sloped embankment (CRSE) by countering the heat absorption of slopes during summers. A coupled thermal-fluid-solid model was built to simulate and assess the cooling performance and reinforcing capacity of the new design. Results show that the crushed-rock embankments can produce convection cooling on the permafrost subgrade but the performances vary with different structures. The CRSE has insufficient cooling capacity to withstand the underlying permafrost degradation in warm permafrost regions. The optimized CRSE that combines the TCVS can effectively cool the underlying warm permafrost and decrease the shady-sunny slope effect under a warming climate, and can be used as an effective reinforcement measure. This study confirms the application of air-cooled embankments in protecting permafrost subgrade and provides guidance for structural design of embankment traversing degrading permafrost.

Numerical simulation on the effects of deteriorating crushed-rock interlayers on thermal stability of embankments in permafrost regions

The crushed-rock layer (CRL) in permafrost regions frequently deteriorates due to aeolian sand, snow accumulation as well as vibrations induced by traffic loads. This degradation can adversely affect the thermal performance of crushed-rock embankments (CREs), potentially causing deviations from their designed specifications. Therefore, it is imperative to thoroughly investigate the thermal stability of CREs under conditions of CRL degradation. By utilizing the crushed-rock interlayer embankment (CRIE) as a representative case, this study employs numerical simulations to analyze six instances of crushed-rock interlayer (CRI) deterioration, employing a mathematical model incorporating adjusted thermal parameters specific to the CRIE. In addition, a novel methodology for quantitatively analyzing temperature distributions within permafrost embankments is employed to assess the results. The findings indicate that all embankment cases lose their cooling capacity on the underlying permafrost prior to the 35th service year. Therefore, mitigating the rate of CRI degradation is essential to preserving the integrity of its underlying permafrost throughout the entire lifespan of the CRIE. The results of this study contribute to the advancement of a theoretical framework for the construction of CRIEs with significant safety margins in permafrost regions.

Optimal sand transport roadbed geometry structure of Taklamakan Desert highway

In order to obtain the optimal geometric structure for sand transport in desert roads, this study fully utilizes the natural sand transport capacity of the desert roads, aiming to reduce occurrences of road damage due to sand burial. The research integrates Computational Fluid Dynamics (CFD) with optimization analysis theory. Various typical geometric structures of desert highway roadbed were modeled using the Design Exploration module in CFD. Optimization analysis methods were employed to model and compute the sediment transport optimization design on both the roadbed and road surface. Then, the initial sample points are obtained by using the Design of Experiments (DOE), and the response surface is established by using the Kriging model to obtain the change trend of the input parameters and the objective function. Finally, the cross-section parameters of the sediment transport subgrade corresponding to different inflow conditions are obtained. The results show that the sediment transport performance of embankment, cutting and semi-filled uphill subgrade is negatively correlated with the height of subgrade. The relationship between slope gradient and sediment transport performance of subgrade depends on the height of subgrade and the type of subgrade section. For embankment and cutting, when the subgrade height is less than 0.5 m, the sediment transport performance of the subgrade is positively correlated with the subgrade slope; however, when the subgrade height exceeds 0.5 m, the sediment transport performance is negatively correlated with the subgrade slope. For the semi-filled uphill flow subgrade, the sediment transport performance of the subgrade is negatively correlated with the subgrade slope. Comprehensive analysis shows that semi-filled and excavated downhill subgrade has the best sand transport performance, embankment subgrade has the second highest sand transport capacity, then cutting subgrades, while semi-filled and excavated uphill subgrade has the worst sand transport performance. The research conclusions provide valuable scientific guidance for the design of sand control embankment structures tailored to local conditions for desert highways. This is of significant importance for enhancing the sediment transport capacity of desert highways and prolonging their service life.

Study on the stable behavior of the river embankment system considering climate change impacts and pressure wave

Understanding the behavior of working conditions of the embankment structural system on reinforced concrete pile foundations is very important in design, construction, operation exploitation, and use. This study assessed the adaptive performance of the Hau River landslide protection embankment in regard to climate change scenarios, specifically the impacts of more extraordinary groundwater table drawdown conditions including pressure waves. The study uses Plaxis 2D V.22 software to simulate and calculate the safety factor of the stability of landslide protection embankment on the right bank of Hau River in the area of Binh Duc Ward, Long Xuyen City, An Giang Province. Simulation. The research results on the effectiveness of shore protection works by the seawall system show that the impact of rising water levels as forecasted by climate change projections (+2.8m elevation) is still within the safe limits. Besides, the dangerous scenario of lowering water levels from the design elevation of -1.0 m (Msf = 1.114) down to the climate change water level of -1.5m elevation (Msf = 1.113)) affecting the protected shoreline also has a minor influence on the stability of the structure. Moreover, the impact of waves on the protection works, which is negligible, is also reduced by the shore protection seawall.

Effects of porosity of crushed-rock layer on cooling performance of crushed-rock embankment in permafrost region of the Qinghai-Tibet Plateau

Effects of porosity of crushed-rock layer on cooling performance of crushed-rock embankment in permafrost region of the Qinghai-Tibet Plateau

Www.ijeit.misuratau.edu.ly ISSN 2410-4256 Paper ID: EN017 Soil Improvement Technique for Pilot Section as New Railway Project in Libya

The construction of embankments on soft saturated soils can be a challenge due to the low shear strength and high compressibility of these soils. The application of reinforced and pile-supported embankments to sustain the imposed dead and traffic loads for train speeds of up to 250 km/h is recently growing in Libya. The aim of this study examine the performance of Geogrid-reinforced embankments with Vibro- stone columns as a ground improvement method adopted in "Pilot Section Al Khoms" subject to cyclic loadings that are applied over a specific area of the embankment to improve strength and provide a safe and economical design for the whole coastal railway. The main result from the load plate test indicates that the stringent performance requirements of the new railway project were met. Furthermore, it was observed that with an increasing number of reinforcement Geogrid layers, enormous cycles of loading could be applied without experiencing excessive deformation and an important reduction in the stress and settlement on the subgrade. The results from field experience, show the project was completed on time and the ground improvement method adopted was employed successfully to reduce the costs of construction maintenance of embankments in the high-speed railway project.

Optimizing Geotechnical Parameters for Sustainable Road Embankments in Flood Disaster-Prone Areas of Bangladesh

The vulnerability of transportation infrastructure to flood disasters in Bangladesh necessitates strategic interventions to optimize geotechnical parameters for sustainable road embankments. This study focuses on a flood disaster-prone region of Bangladesh, aiming to enhance the resilience and sustainability of road infrastructure in the face of recurring floods. The research is driven by the imperative to develop effective engineering strategies that mitigate the impact of floods on road embankments, ensuring safe and reliable transportation networks. The study area is characterized by a complex interplay of geographic and geological factors that contribute to its susceptibility to flooding. Understanding the local geology is crucial for tailoring geotechnical parameters to the specific conditions of the region. Detailed analyses of soil types, their composition, and formation processes provide the foundation for the subsequent optimization efforts. The methodology employed involves systematic sampling along a Road, incorporating both in-situ and laboratory testing. Geotechnical analyses include the evaluation of critical parameters such as California Bearing Ratio (CBR), shear strength, and soil composition. These analyses are instrumental in identifying key geotechnical characteristics that significantly influence the performance of road embankments during flood events. The optimization process encompasses the application of advanced techniques to enhance the resilience of road embankments. The results and subsequent discussions delve into the effectiveness of the optimization strategies in comparison to existing standards and guidelines for road construction. This involves a comprehensive assessment of soil properties, composition, and the outcomes of the optimization process. Finally, the study sheds light on the critical role of geotechnical parameters in developing sustainable road embankments in flood-prone areas. The findings not only contribute to the understanding of the study area but also offer valuable insights for broader applications in flood disaster mitigation in Bangladesh. The research emphasizes the need for a proactive approach to optimize geotechnical parameters, paving the way for resilient and sustainable road infrastructure that can withstand the challenges posed by recurrent floods.

Seismic behavior of highway embankment reinforced with remedial countermeasures on saturated loose sandy layer

A hybrid pile system is proposed to suppress excessive settlement and lateral spreading, which are regarded as main causes of highway embankment failure due to earthquakes. This system, combining two groups of vertical and inclined piles arranged on both sides of highway embankment slope, can be applied to existing highway embankments. In this research, a series of 1 g shaking table tests were performed together with modeling the performance of highway embankments incorporating three cases with different reinforcements subjected to two sinusoidal waves. Several aspects of acceleration time history, pile deformation, and embankment settlement under three configurations were revealed and discussed to confirm the effectiveness of the proposed countermeasures. The results indicate that (1) the hybrid pile system can still ensure sufficient functionality to maintain the highway embankment after two consecutive strong earthquakes; (2) this system can also enhance the integrity of loose sandy layer to reduce the settlement and lateral spreading of embankment; (3) the inclined piles effectively reduce pile head deformation by increasing the shear strength of the pile.

A Transient Seepage–Thermal Stability Model for Cohesionless Soil Slopes in the Semi-Arid Continental Climate of the Canadian Prairies

Seasonal weather variations have a profound effect on the integrity of cohesionless soil slopes in the Canadian Prairies owing to the prevalent semi-arid continental climate. The primary contribution of this research is the development of a transient and two-dimensional stability model that is fully coupled with hydraulic and thermal flows. The model was used to predict the factor of safety (FS) for two slope geometries (18 m height and 26 m height) subjected to three weather scenarios (mean, extreme wet, and extreme dry) and four ponding combinations on the upstream and downstream sides of the slopes under no-load and train-load conditions. Results indicated that for mean climate conditions, FS trends fluctuate till April, followed by an increase that remains constant up to November and decreases thereafter. Generally, the FS shows subdued fluctuations and higher values for the high slope compared with the low slope. For wet climate conditions, the FS patterns are similar to mean conditions, albeit with reduced durations of stability during summer. For dry climate conditions, FS values are higher than mean conditions and nearly constant for most of the year. For no ponding and downstream ponding, FS > 1 throughout the year. In contrast, FS > 1 only during the summer (with reduced time in wet climate and extended time in dry climate conditions) for upstream ponding and upstream–downstream ponding. For train loading, FS shows subdued fluctuations and lower values than the corresponding no-loading scenarios for both slopes. The effects of climate conditions and ponding scenarios are further reduced for the high slope. These findings are useful for decision making with regard to the initial design and ongoing performance of natural slopes and embankments in the cohesionless soils of the region.

Development of a Multiphase Numerical Modeling Approach for Hydromechanical Behavior of Clay Embankments Subject to Weather-Driven Deterioration

Clay embankments used for road, rail, and flood defense infrastructure experience a suite of weather-driven deterioration processes that lead to a progressive loss of hydromechanical performance: micro-scale deformation (e.g., aggregation and desiccation), changes in soil-water retention, loss of strength, and macro-scale deformation. The objective of this study was to develop a numerical modeling approach to simulate the construction and long-term, weather-driven hydromechanical behavior of clay embankments. Subroutines within a numerical modeling package were developed to capture deterioration processes: (1) strength reduction due to wet-dry cycles; (2) bimodality of the near-surface hydraulic behavior; (3) soil-water and soil-gas retentivity functions considering void ratio dependency; and (4) hydraulic and gas conductivity functions considering void ratio dependency. Uniquely, the modeling approach was comprehensively validated using laboratory tests and nine years of field measurements from a full-scale embankment. The modeling approach captured the variation of near-surface soil moisture and matric suction over the monitored period in response to weather cycles. Further, the developed model approach could successfully simulate weather-driven deterioration processes in clay embankments. The model predictions manifested the ability of the modeling approach in capturing deterioration features such as irrecoverable increases in void ratio and hydraulic permeability near surface. The developed and validated numerical modeling approach enables forecasting the long-term performance of clay embankments under a range of projected climate conditions.

Numerical Analysis of Geosynthetic-Reinforced and Pile-Supported Embankments Considering Integrated Soil-Structure Interactions

Geosynthetic-reinforced and pile-supported (GRPS) embankments are becoming more popular as a solution for addressing soil structural instability. The interaction between the geosynthetic-pile-subsoil-embankment elements is crucial to the load transfer mechanism and performance of GRPS embankments. Several analytical models for GRPS embankment design have been proposed, but their performance and applicability still require further validation. This research presents a three-dimensional numerical investigation of the load transfer mechanism of GRPS embankments using the finite difference approach, considering the combined interaction between the soil embankment, geosynthetics, pile, and subsoil. The importance of these crucial aspects in the GRPS embankment design technique is highlighted, as well as their influence and sensitivity. The following elements, in descending order, influence the load and settlement efficacies of the GRPS embankments: soft soil stiffness, embankment height, geosynthetic stiffness, and embankment soil density, according to this research. Furthermore, the use of geosynthetics reduces differential settlements and mitigates soil yielding above the pile heads. The numerical findings are then compared to four well-known design standards, with the subsurface stiffness, geosynthetic stiffness, embankment height, and fill soil density all being varied simultaneously to measure their performance. The findings of the comparison revealed that these techniques differ greatly in their ability to forecast load efficacy and differential settlement. Depending on the geometric properties of the embankment and material properties, all of the selected design methods produce over-predictions or under-predictions.

Coastal and River Embankment Performance at Cengkareng Drain Estuary Under Compound Hazards Conditions Using HEC-RAS 2D

Jakarta is prone to pluvial, fluvial, and coastal flooding due to its geographical location and topography. In response to this problem, the Indonesian government has implemented several master plans, including the National Capital Integrated Coastal Development (NCICD). This ongoing program encompasses the construction of coastal and river embankment that stretch all over the coast of Jakarta. Since many coastal areas in Jakarta are residential or industrial, evaluating this performance of embankment has become crucial for effective flood management. The findings of this research can also support the development of other locations where NCICD embankment plan and enhance coastal resilience. Therefore, this research assessed the effectiveness of coastal and river embankment at Cengkareng Drain, a vital floodway in Jakarta, during extreme events that occur simultaneously. To simulate flooding events, two-dimensional HEC-RAS features were used to numerically calculate the area and depth of inundation. The simulation required geometry, terrain, land cover, and unsteady flow data. For the flow boundary conditions, a 100-year design rainfall, HHWL (Highest High Water Level), and 100-year design wave were considered to represent estuary conditions accurately. The simulation result showed that the maximum water level influenced by these factors was +3.145 mMSL, while the planned embankment top elevation was +3.40 mMSL. Furthermore, without the NCICD embankment, the simulation showed an inundation area of 1212.37 ha, which was reduced to 1111.22 ha after their implementation, leading to a decrease of 101.15 ha. This reduction significantly decreases potential damage to property and infrastructure, particularly in densely populated areas. The simulation also showed a reduction of 86.49 hectares or 66.22% in the inundation area with a depth exceeding 1 meter. These findings demonstrate the effectiveness of embankment in reducing the inundation area without any overtopping incidents.

Numerical analysis of geosynthetic-reinforced embankment performance under moving loads

The performance of geosynthetic-reinforced embankments under traffic moving loads is always a hotspot in the geotechnical engineering field. A three-dimensional (3D) model of a geosynthetic-reinforced embankment without drainage consolidation was established using the finite element software ABAQUS. In this model, the traffic loads were simulated by two moving loads of rectangular pattern, and their amplitude, range, and moving speed were realized by a Fortran subroutine. The embankment fill was simulated by an equivalent linear viscoelastic model, which can reflect its viscoelasticity. The geogrid was simulated by the truss element, and the geocell was simulated by the membrane element. Infinite elements were utilized to weaken the boundary effect caused by the model geometry at the boundaries. Validation of the established numerical model was conducted by comparing the predicted deformations in the cross-section of the geosynthetic-reinforced embankment with those from the existing literature. On this basis, the dynamic stress and strain distribution in the pavement structure layer of the geosynthetic-reinforced embankment under a moving load was also analyzed. Finally, a parametric study was conducted to examine the influences of the different types of reinforcement, overload, and the moving load velocity on the geosynthetic-reinforced embankment.

Role of geofoam inclusions on the liquefaction resilience of transportation geostructures

Though the effectiveness of geofoam buffers for improving the dynamic load response and seismic performance of road embankments and retaining walls is well-established, their role on soil liquefaction is not investigated by many. This study explores the potential of Expanded Polystyrene (EPS) geofoam inclusions for liquefaction mitigation in sands through a series of stress-controlled constant volume cyclic simple shear tests. The study quantifies the increase in liquefaction resistance of sand with geofoam inclusions and reduction in modulus degradation and shear deformations and increase in energy dissipation with loading cycles. Effects of geofoam density and thickness of the layer on the liquefaction response were also investigated through systematic series of experiments with geofoam of three different densities and two different thicknesses. Findings from this experimental study suggest that providing a thick low-density geofoam layer provided the maximum benefit among all the inclusions. Fundamental mechanisms governing this improved response are explored through a series of bender element tests. Results from this study confirm the effectiveness of geofoam buffers in mitigating liquefaction in granular soils and recommend their use in road embankments and retaining walls being constructed in zones of high seismicity to avoid liquefaction and associated lateral spreading failures in these structures.

Surrogate-assisted uncertainty modeling of embankment settlement

The structural optimization of basal reinforced piled embankments is usually conducted by examining design alternatives while ignoring the inherent variability of soil properties and studying only a limited number of structural variables. As an alternative, this paper proposes a hybrid modeling framework to introduce soil property uncertainty into embankment settlement calculations. This is important because settlement is critical in the serviceability assessments considered during structural optimization. The proposed framework consists of uncertainty modeling, finite element method, surrogate modeling, and probabilistic analysis. More specifically, a neural network with Monte Carlo dropout that accounts for uncertainty is employed to correlate the soil properties which affect the long-term performance of embankments over soft clay. Next, a coupled finite element analysis is performed using two constitutive soil parameters generated by the neural network to predict post-construction settlements. Combining the finite element (input source) with a surrogate model (data-driven approximation) yields substantial settlement outcomes for structure evaluations. A case study is then used to validate the effectiveness and applicability of this framework. Finally, an exhaustive search approach is used to design a cost-effective improved ground within ultimate and serviceability limit state constraints. Pareto front is computed using a logistic function at different settlement reliability levels.

The Behavior of Dredged Soil-Shredded Rubber Embankment Stabilized with Natural Minerals as a Road Foundation Layer

Recently, geotechnical studies have been conducted more progressively to utilize dredged soil. The inclusion of shredded rubber (SR) and natural minerals (NM) to stabilize dredged soil (DS) has become an exciting issue in the geotechnical field. This technique can be a promising environmental innovation for the future. This study aimed to investigate the unconfined compressive strength (UCS), California bearing ratio (CBR), and embankment performance under the strip footing test. The UCS sample was prepared using shredded rubber with a proportion of 2% and 3% and natural minerals with a proportion of 3%, 6%, 9%, and 12% from the dry weight of the soil. Whereas for the CBR samples (both in un-soaked and soaked conditions) were also prepared with a proportion of 2% and 3% shredded rubber and 6% and 9% natural minerals from the dry weight of the soil as well. The strip footing test was conducted in small-scale laboratory tests to evaluate the performance of stabilized dredged soil embankments. The applied load test was gradually increased until the embankment collapsed. The results showed that adding shredded rubber and natural minerals could increase the UCS value by 3–4 times and the CBR value by 2–3 times. Furthermore, 84% and 116% efficient results were obtained in the strip footing test for the 7 and 14 days of curing, respectively. Therefore, the utilization of dredged soil stabilized with SR and NM can be considered for use as a road foundation layer. Doi: 10.28991/CEJ-2023-09-05-016 Full Text: PDF

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.