Reinforced Soil Embankments Research Articles

Prediction of Optimal Design Parameters for Reinforced Soil Embankments with Wrapped Faces Using a GA–BP Neural Network

Under the same geological conditions, the thickness and length of the reinforced strip, the slope ratio of the reinforced embankment, the modulus of elasticity of the fill and the reinforced strip, and the friction angle at the interface between the reinforcement and the soil, are the main design parameters that have an important influence on the stress, deformation, and stability of the encompassing reinforced soil embankment. To quickly and accurately determine the optimal design parameters for reinforced soil embankments with wrapped faces, ensuring minimal cost, while maintaining structural safety, we propose a design parameter prediction model based on a GA–BP neural network. This model evaluates parameters within their specified ranges, using maximum lateral displacement, maximum vertical displacement, maximum stress in the XZ direction, the maximum shear strain increment, and the safety factor, as assessment criteria. The primary objective is to minimize the overall cost of the embankment. A comparison with five machine learning algorithms shows that the model has high prediction accuracy, and the optimal design parameter combinations obtained from the optimization search can significantly reduce the cost of the embankment, while controlling the displacement and stability of the embankment. Therefore, the GA–BP network is suitable for predicting the optimal design parameters of reinforced soil embankments with wrapped faces.

Design method for crash attenuation embankments reinforced with geosynthetics

One valid solution for attenuating the crash of a traveling train or truck against buildings and infrastructures is to build a reinforced soil embankment approx. perpendicular to the direction of the vehicle. Such reinforced embankment shall be designed for crash attenuation to absorb even very high impact energy, based on the mass, the size, and the speed of the impacting vehicle. The Authors present a new analytical design method which consider the effect of all the variables playing a role in the resistance to penetration on the uphill face and the resistance to extrusion on the downhill face, in order to finally compute approximate yet consistent values of the penetration depth and of the extrusion length; hence the designer can quickly try different solutions and finally select the best combination of design variables which afford to respect all design limits and Factors of Safety.

Ultimate Load-Bearing Capacity of Rigid Two-Way Pavements Placed on Geosynthetic-Supported Soil Embankment

This study investigates the ultimate load-bearing capacity of rigid two-way concrete pavements placed on conventional and reinforced soil embankments using upper-bound limit analysis (UBLA). In the presence of the median strip, upper-bound solutions of rigid pavements resting on reinforced embankments did not draw much attention from previous researchers. Therefore, a rigorous UBLA is performed, adopting the multi-block failure mechanism for the intended purpose. The true upper-bound solution is achieved by satisfying the conditions of geometric compatibility and kinematic admissibility. The effects of the proximity of dual carriageways and embankment slopes on the load-bearing capacity of pavements are expressed in relation to interaction factors. The critical spacing beyond which the proximity effect ceases to exist is estimated for different slope angles of the embankment. A parametric investigation is performed to understand the influence of various soil parameters, embankment geometry, and layers of reinforcement. A notable improvement in the performance of two closely spaced rigid pavements can be observed by providing additional layers of reinforcement. The current outcomes are sensible and match well with the existing investigations.

Behavior of Reinforced Gypseous Soil Embankment Model under Cyclic Loading

The construction of embankment for roadway interchange system at urban area is restricted due to the large geometry requirements, since the value of land required for such construction is high, and the area available is limited as compared to rural area. One of the optimum solutions to such problem is the earth reinforcement technique which requires a limited area for embankment construction. Gypseous soil from Al-Anbar governorate area was obtained and subjected to various physical and chemical analysis to determine it is properties. A laboratory model box of 50x50x25 cm was used as a representative embankment; soil has been compacted in five layers at maximum dry density (modified compaction) and an aluminum reinforcement strips were introduced between layers. The model was subjected to cyclic loading and the vertical and lateral deformations were detected at different stages of loading cycles using LVDT. The reinforced soil embankment under soaking condition exhibited vertical settlement at the top surface was (12.55 mm) while the lateral displacements at (1st, 3rd layer) were (2.18, 1.32) mm respectively at (47 load cycles).For reinforced gypseous soil, embankment without soaking cured for 24 hours, the Number of load cycles was found to be (165) loading cycles with vertical displacement (9.12 mm), that means an improvement of 59%. Accordingly, the lateral displacement in 1st and 3rd layers were (3.28, 2.59) mm respectively which observes improvement by (28% and 5%) respectively. The rates of improvement are taken with respect to the reinforced pure dry soil sample.

Study on the Mechanical Properties of Flexible Prefabricated Highway Structural Systems considering the Effect of Two-Way Fluid-Structure Interaction

The rainfall often causes changes in the physical performance of the embankment, which leads to disasters such as embankment collapse and road surface settlement and cracking. Past research has tended to be limited to traditional embankment seepage models and is mostly based on the assumption that surface precipitation is uniform and rainfall intensity is constant. To adapt to the changes and development of the times, based on the water leakage mode of the flexibly assembled highway embankment, a new rainfall calculation model of the reinforced soil embankment is constructed and combined with the solid-fluid coupling physics theory, the sedimentation amount and slope stability of the embankment are analyzed at multiple levels, the mechanical properties of the new embankment under rainfall conditions are summarized, the factors affecting the settlement of the embankment and the stability of the slope are explored, and the reference model is provided for the construction of the new embankment, and the existing construction process is improved through multilevel cause analysis. We improve and develop the existing theoretical system to reduce the probability of road diseases, improve the efficiency of road construction, and reduce the cost of road maintenance.

Upper-bound limit load of rigid pavements resting on reinforced soil embankments – Kinematic approach

This study evaluates the influence of inclined ground on the ultimate load-carrying capacity of rigid concrete pavements laying on unreinforced and reinforced soil embankments. The solution procedure is developed based on the kinematic approach of the limit analysis. The carrying capacity is sequentially obtained by satisfying the energy principle of the upper-bound theorem alongside the associated flow rule. A multi-block collapse mechanism is assumed for the intended purpose, which is later optimized to obtain the proper upper-bound limit solution. The ultimate carrying capacity of the pavement is seen to be improved further by reinforcing the embankment and modifying the soil properties. The effect of individual parameters influencing the results is discussed in detail. The available bearing capacity theories developed for rigid foundations are invoked for validation and comparison to bolster the legitimacy of the present solution.

LANDFILLS VOLUME INCREASE WITH REINFORCED SOIL EMBANKMENTS: BASIC THEORY AND CASE STUDIES

The construction of controlled landfills, either for municipal or industrial wastes, is currently acknowledged worldwide as a 'social need". Indeed, today one of the main societal issues is the identification of an optimal means of disposing of the huge quantities of urban and industrial waste produced on a daily basis by individuals and factories. The task of environmental engineers is to design landfill systems capable to prevent any pollution to the water, the air, and the surrounding fauna and human life. In densely populated countries, the first problem to be solved is the location of the landfill. This social confrontation often leads to locate the landfill not in most geologically and geotechnically suited site, but in marginal areas which finally satisfy all the fighting communities. More and more geosynthetics are used to solve the problems associated with landfills located in marginal areas. The use of geogrids to construct steep reinforced embankments with the aim to increase the volume of wastes that can be disposed and at the same time to increase the stability of the wastes themselves, is getting more and more diffused. The paper describes the use of geosynthetics reinforced soil structures to increase the landfill volume with reinforced soil embankments. Some examples of structures already constructed, either for industrial or municipal wastes landfills, are described.

The influence of geosynthetics design on the behavior of reinforced soil embankments subjected to rockfall impacts

Rockfall hazard in mountainous areas requires the construction of protective structures for the buildings or transport facilities. Reinforced soil embankments can be effective protections against rockfalls due to the combination of the damping characteristics of the soil and the tensile resistance of the reinforcements. Following the advances in soil reinforcements, the research is ongoing for this type of structures aiming to optimize their shape and reinforcement design. In order to study the influence of the different geosynthetics design, two reinforced soil embankments are tested experimentally. The embankments had vertical facings and a slenderness ratio of two with the purpose to reduce the footprint of the conventional trapezoidal shape. Embankment 1 had two vertical layers of geogrids that divided its cross section in three equal parts, while Embankment 2 had multiple geogrid strips installed horizontally close to the front facing. Horizontal impact tests are performed on the two embankments using reinforced concrete blocks as impactors with the aid of a pendulum device. Several instruments and sensors are used to monitor the behavior of the embankments, namely accelerometers, pressure sensors, strain gauges, rapid cameras and a laser scanner. During the tests, the two embankments experienced local shearing at the impact position and overall backward leaning. Moreover, a waves' propagation effect is observed during the first moments of the impact at the sensors installed in the embankments. The speed of the propagation of these waves appears to be influenced by the reinforcement design of the embankments. After the tests, Embankment 2 was less deformed than Embankment 1, which is attributed to their different reinforcement design. According to the strain gauges measurements, the geogrids of Embankment 2 were more mobilized in the vicinity of the impact compared to the ones of Embankment 1. These tests showed that the geogrids installed in horizontal position close to the front facing are more efficient compared to the ones installed vertically and deeper in the embankment. • The tested reinforced soil embankments have vertical facings for foundation optimization. • The reinforced soil embankments have a slenderness ratio of two. • The geosynthetics design plays an important role in the impact response of embankments. • The tested embankments are vulnerable with regard to structural stability. • The impact waves propagation is demonstrated by accelerometers, pressure sensors and strain gauges.

Performance of a 33m high geogrid reinforced soil embankment without concrete panel

Geosynthetic reinforced soil embankment are extensively applied in the construction of high-speed railway and highway in mountainous regions but limited field monitoring is conducted on high and steep cases. Aiming to acquire better understanding, a 33-m-high single-tiered wrapped-facing geogrid reinforced soil embankment with the slope of 1 V:0.5H in China was monitored for 2 years during and after construction. Vertical earth pressure, strain of geogrids, horizontal displacement and settlement per layer were recorded and analysed. The results show that the geogrid tensile strains gradually increased during construction. And they were still developing after completion due to creep and subsequent vehicle surcharge load. The predictions of reinforcement loads by the FHWA methods were much higher than the estimated ones from measured strains. The vertical earth pressures linearly grew during construction and then stabilized fast. The horizontal displacement increases with height and the largest value achieved around the top of the slope two years after the construction is 0.14% the total height approximately. The settlement per layer is larger in the lower and middle portion of the embankment and no obvious change is observed over time. This study hopes to serve as a case reference for design and construction of similar reinforcement projects in the future.

Modeling and Analysis of Ground Settlement Between a Flyover and Reinforced Soil Embankment

AbstractDevelopment of the transport infrastructure in Poland has contributed to the implementation of various technologies of construction of bridges and their components. Use of reinforced soil for construction of embankments, retaining structures (RSS walls) and abutments is one of the solutions which has been frequently used for the past twenty years. Shortly after its development, the technology proposed by Henri Vidal in 1966 also gained appreciation in Poland [4]. Reinforced soil bridge abutments started to be widely used in Poland at the turn of the 20th century. The bridge facilities at the junction of Trasa Siekierkowska route and Wał Miedzeszyński Street in Warsaw, which were built in the years 2000÷2002, are an example of structures from that period. The authors of this paper have been particularly interested in the outermost supports of the reinforced concrete flyovers which were constructed in the form of intermediate reinforced soil abutments. Offsets – the vertical displacements, in the range of 15÷25mm, emerging between the level of the road surface and the steel elements of the expansion joints which separate the flyover’s structure from the embankment – were observed in 2015, in the course of regular inspections. While accounting for the observations which have been made, the surveying measurements and the ground investigation, the paper diagnoses and describes the mechanism which led to the emergence of the offsets. Potential patterns of the occurrence of additional settlements, as the reason for emergence of the offsets, were identified and analyzed. The settlement of the outermost support (abutment), as a result of increase of relative density of alluvial sands due to the dynamic interaction of the roadways of Wał Miedzeszyński Street, was analyzed. Analytical and numeric approaches were used in the course of analysis while relying on PLAXIS and MIDAS software.

Geotechnical consideration of the cut‐and‐fill slope problems related to the Struma motorway construction

AbstractThe forthcoming construction of the Struma motorway which is part of the Pan‐European corridor IV is one of the most challenging geotechnical assignments in Bulgaria nowadays. The road trace is situated in a region of high seismic activity where the topography reveals mostly areas with steep mountain slopes. Geotechnical considerations of the road construction including cut‐and‐fill works and building of different supporting structures as pile founded retaining structures, anchor systems and reinforced soil embankments is needed. Numerical solutions based on the limit equilibrium theory and the finite element method are applied. This paper analyses and summarizes the design options and the results of the different numerical models of preferred structures.

Impact of Asphalt Stabilization on Deformation Behavior of Reinforced Soil Embankment Model under Cyclic Loading

Gypseous soil, which covers vast area in west, middle, east and south west regions of Iraq exhibit acceptable strength properties when dry, but it is weak and collapsible when it comes in touch with moisture from rain or other sources. When such weak soil is adopted for earth reinforced embankment construction, it may exhibit hazardous situation. Gypseous soil was in- vestigated for the optimum liquid asphalt requirements of both cutback and emulsion using the one-dimensional unconfined compression strength test. The optimum fluid content was 13% (7% of cutback with 6% water content), and 17% (9% of emulsion with 8% water content). A laboratory model box of 50x50x25 cm was used as a representative of embankment; soil or asphalt stabilized soil have been compacted in five layers at maximum dry density (modified compaction) and an aluminum reinforcement strips were introduced between layers and connected to the facing strips. The model was subjected to cyclic loading and the lateral deformation of facing strips and the vertical deformation were detected at different stages of loading cycles and different height of the facing strips using LVDT. The reference embankment model was that of reinforced pure soil under absorbed condition. For asphalt-stabilized soil, the cutback asphalt stabilized- soil model exhibit improvement in load carrying capacity by nine folds. It shows a reduction of 23% in vertical displacement under sustained load of 436 repetitions. For emulsion-stabilized soil, the reduction in vertical displacement was 38.5% under a sustained load of 950 cycles. The load carrying capacity was improved by twenty folds. The lateral displacement at the upper first and third layers were lower by 0.55% and 1.9% respectively when compared to cutback asphalt stabilized model.

Performance of instrumented large-scale unreinforced and reinforced embankments loaded by a strip footing to failure

The paper describes an experimental investigation in which two large-scale geosynthetic reinforced soil embankments and one unreinforced soil embankment were taken to collapse under a strip footing placed close to the crest. One reinforced embankment was constructed with a relatively extensible and weak polypropylene geogrid and the second with a relatively strong and stiff high-density polyethylene geogrid. The geometry of the unfaced embankments, sand soil, and loading arrangement were the same for all three structures. The focus of the paper is on the experimental design, construction, testing, and instrumentation techniques used in the investigation and selected test results. The results of the study show that the ultimate footing load capacity increased with an increase in reinforcement strength (and stiffness) and that the reinforced soil embankments had a load capacity up to 1.6–2.0 times that of the nominal identical control embankment without reinforcement.Key words: geosynthetics, reinforced embankments, strip footing, large scale, experimental.

Limit equilibrium analysis of large-scale reinforced and unreinforced embankments loaded by a strip footing

The paper describes limit equilibrium analyses of two large-scale geosynthetic reinforced soil embankments and one unreinforced soil embankment that were taken to collapse under a strip footing placed close to the crest. One reinforced embankment was constructed with a relatively extensible and weak polypropylene geogrid and the second with a relatively strong and stiff high-density polyethylene geogrid. The geometry of the embankments and the loading arrangement were the same for all three structures. The focus of the paper is on a comparison of the predicted collapse load for the three structures and the actual observed values. A three-dimensional analytical approach is used to account for possible side-wall friction effects due to the test facility in which the large-scale experimental models were built. The paper also reports details on the interpretation of in-isolation constant load tests and strain measurements used to infer tensile loads in the reinforcement at failure. An important conclusion is that a general two-part wedge analysis approach can be used to predict the collapse footing load for both unreinforced and reinforced sand embankments in this investigation provided careful attention is paid to the selection of soil shear strength and reinforcement tensile capacity.Key words: geosynthetics, reinforced embankments, strip footing, large scale, limit equilibrium analyses.

Internal Forces Tests in Retaining Walls of Road Embankments

The subjects of this paper are resistance structures constituted by reinforced soil applied in highway engineering. Test results carried out on laboratory models are presented, leading to the estimation of the size and shape of the wedge of the reinforced soil embankment block, in the boundary state of active pressure. The task was conducted in the following two stages: on the basis of measured horizontal strains of the embankment (unitary lateral pressures) and reinforcing dowels - with the application of sensors of electro-resistant tensometry. The slip curve, determining the searched block wedge, is formed by the points of maximal normal stress occurring in the reinforcement dowels located in the horizontal layers. The slip curve divides the embankment area into two zones: active (block wedge) and passive, in which dowel anchorage takes place.

Optimization of reinforced soil embankments by genetic algorithm

A Genetic Algorithm (GA) is described, which produces solutions to the cost optimization problem of reinforcement layout for reinforced soil slopes. These solutions incorporate different types of reinforcement within a single slope. The GA described is implemented with the aim of optimizing the cost of materials for the preliminary layout of reinforced soil embankments. The slope design method chosen is the U.K. Department of Transport HA 68/94 ‘Design Methods for the Reinforcement of Highway Slopes by Reinforced Soil and Soil Nailing Techniques’. The results confirm that there is a role for the GA in optimization of reinforced soil design. Copyright © 2000 John Wiley & Sons, Ltd.

Design of geosynthetic reinforced embankments on soft soil

The present paper investigates the performance of geosynthetic reinforced soil embankments on soft clays. The limit equilibrium method has been considered. Design charts for various embankment slopes are proposed and reported in this paper for the user's sake.

First Step Research on Reinforced Soil Embankments with Cohesive Soils

Reinforced soil embankments deform by percolation of rain water after end of construction. There are cases which can be allowable and not. Why such deformation occur should be investigated. Noticing that those deformation are due to physical properties of soil, relationship between stress-strain relationship was studied by the laboratory rest. The deformation property is expressed by coefficient of linear deformation and Poisson's ratio or Poisson's number. Usually fill materials contain large gravels. As fills are relatively low, stresses in the fills are low. These conditions should be taken into account when the testing apparatus is designed. A large steel sylinder attached by wire strain gages filled with soil sample was subjected to vertical load by a jack. Coefficient of linear deformation and Poisson's number were obtained by computation. A kind of simple shear apparatus was used to obtain shear modulus. soil sample

14 metre high reinforced soil embankment as the abutment of a steel bridge in Tuen Mun, Hong Kong : Ng, H Y; Mak, C H Proc International Geotechnical Symposium on Theory and Practice of Earth Reinforcement, Fukuoka Kyushu, 5–7 October 1988P449–454. Publ Rotterdam: A A Balkema, 1988

14 metre high reinforced soil embankment as the abutment of a steel bridge in Tuen Mun, Hong Kong : Ng, H Y; Mak, C H Proc International Geotechnical Symposium on Theory and Practice of Earth Reinforcement, Fukuoka Kyushu, 5–7 October 1988P449–454. Publ Rotterdam: A A Balkema, 1988

Instrumented steep reinforced soil embankment at Andalsnes, Norway : Hermann, S; Burd, H J Geotext GeomemV7, N4, 1988, P293–308

Instrumented steep reinforced soil embankment at Andalsnes, Norway : Hermann, S; Burd, H J Geotext GeomemV7, N4, 1988, P293–308