Performance Of Embankment Research Articles

Comparison of Field Performance between Bamboo-Geotextile Composite Embankment and High Strength Geotextile Embankment

Trial embankment approximately 3 meters height, 10 meters of length, 16 meters width, and a slope of 1V: 2H was completed on soft clay site at RECESS, UTHM, Batu Pahat, Johor, Malaysia. Two embankments were respectively reinforced by a high strength geotextile (HSG) and the combination of bamboo and low strength geotextile or bamboo-geotextile composite (BGC) at the interface between embankment fill and foundation soil. Each embankment was installed with the same geotechnical instrumentation scheme for monitoring purposes. The purpose of this paper is to analyse the field performance for both embankments in terms of improving settlement embankment under the embankment. For this purpose, the settlement under the embankment, settlement at the surface of the embankment and the excess pore water pressure response were measured through geotechnical instrumentation for over 418 days. The results showed that the BGC system is more practical than HSG in terms of settlement and also in terms of cost, without compromising the quality of the embankment performance.

The Finite Element Analysis and Experimental Study of Fly Ash Embankment Reinforcement

This paper presents the effect of two-directional reinforced with geogrid on the performance of embankment, and carries out model experiment and numerical simulation on fly ash embankment. Finally, the curve of relationship among the embankment deformation, the amount of reinforcement and reinforced position was obtained. In addition, the optimum geogrids-reinforced project was also disscussed. The disscussion has some positive effect on the design of reinforced embankment of fly ash.

Reliability of flood embankments: a new methodology

Predicting the structural performance of embankments in extreme hydraulic conditions is essential to flood risk assessment. It is, however, a difficult task, owing to the general lack of information about the characteristics and conditions of earth structures in geographically extended and heterogeneous flood defence networks. The approach to flood embankment reliability currently adopted in the UK has some problematic aspects. In particular, the modelling of piping through the embankment is not completely satisfactory. Moreover, the use of condition grades, which lump together factors affecting different failure modes, may be misleading. The methodology presented in this paper, developed to overcome these limitations, is based on the estimate of the probability of breaching associated with a limited range of water levels. In this work, while other failure modes are treated with the traditional methods of structural reliability, through-piping is addressed with a rigorous elicitation of subjective probabilities. The methodology explicitly links the lack of knowledge to the uncertainty about the performance prediction. The final users are provided with tabulated solutions for a quick reliability assessment, the evaluation of uncertainty and the identification of the information needed to produce a better prediction.

Embankment and Changing Micro-Topography of Lower Ajoy Basin in Eastern India

This paper deals with the impact of river embankment on the physical environment of the river. Different types of flood control measures are in practice. Embankment is supposed to be an important structural measure of flood control. The performance of embankment varies from case to case. It is quite effective for short term flood alleviation, but it puts a question regarding the long term viability of the embankment and become harmful to the adjacent floodplain. Morphology of the river as well as the micro-topography of the floodplain undergoes great changes as a result of confinement of river flow due to construction of embankment. With this concept in background a geomorphological study has done in the Lower Ajoy Basin of Eastern India. The chronological study about cross-sections of some selected sites of the river, have proved the reduction of the channel depth. Huge sandsplays over the floodplain after the breaching of embankments have changed the micro-morphological character. The present study is to find out the extent of change in the micro-topography caused by Ajoy embankment. Key Words: Embankment, Floodplain, Micro-topography, Sandsplays,

Numerical Analysis of Seismic Performance of Embankment Supported by Micropiles

This paper presents a numerical model of the seismic behavior for the embankment constructed on micropile composite foundation. The effect of micropiles on soil reinforcement under static and seismic loading was studied. Embankments on the untreated and treated soil by micropiles were numerically simulated using an axisymmetric elastoplastic large deformation finite-element analysis code. The displacement caused by embankment static loading and acceleration of the embankment caused by seismic loading were calculated and compared. It was shown that micropiles can greatly reduce the settlement of the embankment and mitigate seismic response of the embankment. The main objective of this paper is to present a numerical model and to investigate the seismic behavior of micropile foundations subjected to seismic loading. A series of numerical simulations and parametric studies are presented.

The Interaction Between Reinforcement and Vertical Drains and Effect on the Performance of Embankments on Soft Ground

This paper reviews the behaviour of reinforced embankments on soft ground. Case of the Almere test embankment is used as an example to demonstrate the key function of reinforcement in improving the performance of embankments on soft foundation. The effects of partial drainage are summarized for reinforced embankments and contrasted the results from undrained analyses to highlight the effect of partial consolidation during construction. Effects of the interaction between reinforcement and prefabricated vertical drains (PVDs) are presented. It is concluded that the combined effects of partial consolidation provided by PVDs and the tension mobilized in reinforcement can substantially increase the stability of an embankment on a given soft soil. This paper also provides brief explanation of a recent design approach for embankments on soft soil, considering the combined effect of reinforcement and PVDs. Effects of the creep/relaxation characteristics of geosynthetic reinforcement and rate-sensitive nature of soft cohesive foundation soil are discussed. It is shown that time-dependent nature of geosynthetics and foundation can decrease the failure height of a reinforced embankment. Also, the long-term performances of a reinforced embankment can vary significantly depending on the soil and reinforcement characteristics. The results suggest the need for care when the foundation soil is rate-sensitive.

Monitoring and Performance of Embankments on Soft Soil: Juturnaíba Trial Embankment and Other Experiences in Brazil

The accurate performance of instrumentation is fundamental to the adequate use of the results obtained from analyzing the behavior of constructions of embankments on soft soils. When evaluating embankment behavior, the geotechnical instrumentation for pore pressure and vertical and horizontal displacements measurements can be an extremely useful tool, including when there are adjacent structures. This paper presents the results of monitoring and analysis of the performance of embankments on soft soil, carried out by the Geotechnical Group (GEGEP) of the Federal University of Pernambuco. Three Brazilian cases are presented: the Juturnaíba trial embankment and Juturnaíba Dam construction, in Rio de Janeiro; and the access embankments of the Jitituba River Bridge, in Alagoas. The analysis of embankment behavior was performed by using the traditional model (undrained condition during construction) and the Tavenas & Leroueil (1980) model (partially drained condition during construction). The results showed that it is possible to predict embankment behavior. They also showed the complexity of this topic and the importance of monitoring and evaluating each case in accordance with the location and the type of instrument, subsoil and embankment conditions.

A Multi-Parameter Correlation for Predicting the Seismic Displacement of an Earth Dam or Embankment

Predictive displacement-based methods provide a useful index of the seismic performance of earth dams and embankments and can be used in preliminary assessments of these structures. In practice, simplified Newmark-type sliding block methods are commonly used for this purpose. Using a database of 122 previously published case histories of permanent deformations of earth dams and embankments, the performance of six simplified sliding block models was examined. The results show that all six simplified methods underpredict seismic displacement for many of the embankment and earth dam cases that were examined, sometimes by a significant amount. An empirical correlation was developed by performing linear multiple regression analysis utilizing multiple slope and ground motion input parameters. This approach is believed to more properly reflect strong ground motion characteristics than the use of a single ground motion parameter such as the peak ground acceleration, the approach that has been previously employed in other correlations of this type. After exploring numerous functional forms, the final resulting seismic displacement correlation that was proposed was determined to be a function of the critical acceleration, the critical acceleration ratio, the slope height, the peak ground acceleration, the peak ground velocity, the spectral acceleration, and the predominant period of earthquake shaking. The proposed empirical equation yields better correlation with the case history database than does other existing empirical correlations or simplified sliding block models.

Arthur Penman and his contributions to embankment dam engineering

Throughout six decades Arthur Penman made a major contribution to embankment dam engineering as it developed from a largely empirically based activity into a science-based discipline where modern developments in geotechnical engineering have a major role. His pioneering development of practical and reliable field instrumentation facilitated the monitoring of embankment performance which alone could validate the increasing use of numerical analysis. A great enthusiasm for embankment dams continued into the final years of his life.

Performance of Pile-Supported Embankment over Soft Soil: Full-Scale Experiment

AbstractThis paper describes a full-scale experiment of pile-supported embankments on soft soil, which is conducted within the French national research project, Amelioration des Sols par Inclusions RIgides (ASIRI), to provide a new design method. This experiment shows the great influence of a granular platform reinforced with geosynthetics in load-transfer mechanisms. The measurements of geosynthetic strains highlight that the maximum strain takes place at the vicinity of pile heads during the construction of an embankment. Measurements also show that the load-transfer behavior of a platform reinforced by a single geotextile is different from that of a platform reinforced by two geogrids, although the final settlement is the same in both sections. From the important measurement data of this full-scale experiment, some considerations on the design and the efficiency evaluation have been proposed.

Design of reinforced embankments on soft clay deposits considering the viscosity of both foundation and reinforcement

The combined effects of the viscoplastic nature of foundation soil and viscoelastic behaviour of geosynthetic reinforcement (polyester, polypropylene and polyethylene) are investigated. A new method for defining the critical stage, with respect to embankment stability, and the operational field strain rate for use in assessing the undrained shear strength of rate-sensitive foundation soils similar to those examined is proposed. The effect of construction rate on the reinforcement stiffness at the critical stage is examined. The study shows that the selection of a design stiffness using the data obtained from a creep test provided reasonable and conservative results. The effects of the undrained shear strength profile, reinforcement stiffness and soil viscosity on embankment performance under working stress conditions are explored and a new limit equilibrium based design procedure is proposed. Finite Element analyses are used to examine the potential effectiveness of the proposed simplified design procedure.

The thermal effect of differential solar exposure on embankments along the Qinghai–Tibet Railway

The difference in solar radiation produces a predictable thermal effect on the sunny and shaded slopes of embankments constructed in permafrost regions of the Qinghai–Tibet Highway and Railway, which results in differences in soil temperatures and the permafrost table under the shoulder. From the period 2005 to 2008, a systemic network of 42 sites was established along the Qinghai–Tibet Railway to monitor permafrost conditions and embankment performance. Soil temperatures up to 20 m in depth under the embankment were continuously measured hourly. In this article, we investigate daily mean soil temperatures under embankments for 25 observed sites and the temperature difference under the shoulder for both the sunny and shaded slopes of the embankments. We found significant differences in the thermal effect from the sunny and shaded slopes of the embankments along the Qinghai–Tibet Railway. On the sunny slope of the embankment the cooling process of soils under the shoulder is shorter and the thawing process is longer by 15–30 days than on the shaded slope. The multiyear average temperatures under the shoulder for the sunny slope are higher—0.23–1.58 °C with an average of 0.86 °C—than those for the shaded slope. The temperature differences in winter (DJF) are much larger than those in summer (JJA). The multiyear mean permafrost table under the shoulder for the sunny slope of the embankment is larger than for the shaded slope, ranging from 0.1 to 3 m, with an average of 1.13 m. However, engineering measures can effectively reduce the thermal effect between the sunny and shaded slopes of embankments, resulting in a decreasing temperature difference that ranges from 0.46 to 0.71 °C, with an average of 0.58 °C. ► Differential solar exposure on embankment slope caused thermal effect difference. ► Differential solar exposure on embankment slope depends on embankments orientation. ► Thermal effect leads to permafrost temperatures and table difference under embankment.

Development and Characterization of Soil Material Parameters for Embankment Breach

Despite the widespread use of earthen dams, the processes by which earthen embankments erode and fail when overtopped during extreme events are only imperfectly understood. Aging of these dams and the associated recent focus on dam rehabilitation has increased the need for new technology and tools for predicting the performance of earthen embankments during overtopping. Windows Dam Analysis Modules (WinDAM B) is a modular software application being developed to address this need for homogeneous earthen embankments. This software is being developed through joint efforts of the Agricultural Research Service, the Natural Resources Conservation Service, and Kansas State University. The computational model being incorporated into this software is the result of research including embankment overtopping tests conducted in the outdoor laboratory. The WinDAM B model is a simplified representation of the observed process of progressive erosion leading to embankment breach to be useful for field application the model has been developed to utilize soil parameters that may be reasonably obtained for the conditions to which the model is applied. This article presents the background for the material parameter input requirements for overtopping erosion and breach analysis including: 1) the detachment rate coefficient and critical stress parameters of the excess stress equation, 2) the total unit weight of soil, 3) the undrained shear strength, and 4) the headcut migration coefficient.

Performance of Reinforced Embankments on Rate-Sensitive Soils under Working Conditions Considering Effect of Reinforcement Viscosity

The long-term performance of embankments with creep susceptible geosynthetics as a basal reinforcement layer over rate-sensitive soils is examined. Various factors, including reinforcement type and stiffness, soil viscosity, construction rate, and allowable long-term reinforcement strain, affecting the time-dependent behavior of reinforced embankments are investigated. Increasing the reinforcement stiffness (for a given allowable strain) allowed construction of higher embankments from a stability perspective; however, it also resulted in larger deformations and potential serviceability issues. Lateral toe spreading, maximum settlement, and differential settlement increased with the increasing rate of construction. Reducing the allowable long-term reinforcement strain proved to be an effective means of limiting embankment deformation. The analyses also showed that if the long-term reinforcement strain can be limited to <5% and combined with the practical rate of construction, the long-term deformations of reinforced embankments can be controlled.

The performance of an embankment on soft ground reinforced with geosynthetics and pile walls

The construction of high embankments on soft ground faces several challenges, such as potential bearing capacity failure, global slope instability, local failure, large total and/or differential settlements, and large lateral movement during both construction and post-construction periods. Horizontal geosynthetic reinforcement combined with vertical reinforcement using piles or pile walls can provide an economical and effective solution to ground improvement to support high embankments. This paper reports the results of a numerical study on the performance of embankments on soft ground with three different reinforcement conditions: (1) unreinforced, (2) reinforced with geosynthetics, (3) reinforced with both geosynthetics and pile walls. The influencing factors, such as the tensile stiffness of the geosynthetic, the number of geosynthetic layers, the elastic modulus of the pile wall, and the pile wall distance ratio, on the interaction of geosynthetic-pile wall-soil systems were investigated and the distribution and dissipation of excess pore water pressure in the soil were examined. The numerical results show that a combination of geosynthetic reinforcement and the pile walls was very effective for the improvement of soft ground. The numerical results were shown to be in good agreement with the field data observed at the end of consolidation.

Centrifuge modelling of climatic effects on clay embankments

This paper presents an experimental methodology using a geotechnical centrifuge and an environmental chamber to explore long-term embankment performance in light of the more severe conditions expected due to global climate change. The environmental chamber applies water and air input to control inundation and evaporation conditions at the soil surface. Example results show that a well-compacted intermediate-plasticity model embankment performs well when subjected to 19 years of alternating wet and dry periods. Finally, the paper reports an experimental methodology that will allow further model tests to be conducted to examine how different climate scenarios, soil types and compaction levels may affect long-term embankment response.

Implications of pyritic rockfill on performance of embankment dams

Evidence from the extractive industries shows the impact of the historic use of pyritic materials as rockfill in tailings management and mine waste disposal facilities and demonstrates the often detrimental influence on geotechnical and geochemical performance. The oxidation of pyrite and other sulphide minerals can result in significant changes in the structural zones of embankment dams, and may have serious implications for the construction of both tailings-confining and water-retaining structures. The presentation on this topic at the 2006 BDS conference in Durham revealed a surprising lack of knowledge on the subject among many dam engineers. This paper presents, in summary, the geotechnical and geochemical implications of the untoward inclusion of even small quantities of pyritic rockfill on embankment performance using, in particular, a recent embankment rehabilitation project in Portugal to exemplify the associated problems. The paper concludes with a brief review of the methods available to correct the effects of oxidation within an embankment and to improve stability and environmental performance.

Seismic Performance and Verification of Embankment on Large-scale Earthquake

Seismic Performance and Verification of Embankment on Large-scale Earthquake

Combined effect of PVDs and reinforcement on embankments over rate-sensitive soils

A numerical study of the behavior of geosynthetic-reinforced embankments constructed on soft rate-sensitive soil with and without prefabricated vertical drains (PVDs) is described. The time-dependent stress–strain-strength characteristic of rate-sensitive soil is taken into account using an elasto-viscoplastic constitutive model. The effects of reinforcement stiffness, construction rate, soil viscosity as well as PVD spacing are examined both during and following construction. A sensitivity analysis shows the effect of construction rate and PVD spacing on the short-term and long-term stability of reinforced embankments and the mobilized reinforcement strain. For rate-sensitive soils, the critical period with respect to the stability of the embankment occurs after the end of the construction due to a delayed, creep-induced, build-up of excess pore pressure in the viscous foundation soil. PVDs substantially reduce the effect of creep-induced excess pore pressure, and hence not only allow a faster rate of consolidation but also improve the long-term stability of the reinforced embankment. Furthermore, PVDs work together with geosynthetic reinforcement to minimize the differential settlement and lateral deformation of the foundation. The combined use of the geosynthetic reinforcement and PVDs enhances embankment performance substantially more than the use of either method of soil improvement alone.

Performance Monitoring of Embankments Containing Tire Chips: Case Study

Tire chips (or shredded tires) have been successfully used as a filler material in a number of embankments, but this use has also led to problems such as spontaneous combustion, settlement, and so on. To ensure proper construction and to avoid such problems, the Texas Department of Transportation sponsored a study to monitor the performance of embankments constructed of tire shred fill material in El Paso, Texas. Three embankments, consisting of (1) a mixture of soil and shredded tires; (2) shredded tires wrapped in a geotextile; and (3) a reference embankment built with conventional soil, were instrumented and monitored. The performance of the embankments in terms of vertical settlement, temperature change, and air and water constituency changes were monitored. The performance of these three embankments has shown that there is little potential for environmental impacts in a climate like that of El Paso, and that the construction techniques employed limited the settlements in comparison with some previous experiences.