Yes / Reinforced piled embankment technique is becoming increasingly utilised for the construction over soft grounds due to its efficiency on reducing potential settlement, speed of construction and associated cost. Most of previous studies focused on developing understanding for the behaviour of thick embankments that are loaded with a static surcharge load. Data for the behaviour of shallow piled embankments under cyclic loadings are scarce. In this study, an experimental programme was undertaken using a fully instrumented testing rig to generate data and improve our understanding for the behaviour of unreinforced and reinforced shallow piled embankments subject to monotonic and cyclic loadings that were applied over a predetermined area of the embankment. The experimental results showed that collapse of soil arching is imminent and occurs during the first few cycles of load. However, regain of strength and recovery of the arching effect was observable during further stages of cyclic loadings due to densification of the embankment material and deformation of the soft subsoil. Inclusion of reinforcement layers was found to enhance the performance of load transfer mechanisms by concentrating stresses on pile caps. The results clearly showed a significant reduction in surface settlement, soft subsoil settlement and heaving with increasing the number of reinforcement layers.

Reinforced piled embankment technique is becoming increasingly utilised for the construction over soft grounds. Most of the studies focused on studying the behaviour of piled embankments that are loaded with static surcharge load. However, less attention has been given to the behaviour of piled embankments under cyclic loading conditions. In this study, an experimental programme has been undertaken to improve our understanding for the behaviour of unreinforced and reinforced shallow piled embankments subject to cyclic loadings that are applied over a specific area of the embankment. The results showed that arching of the soil was adversely affected during the initial stages of cyclic loading regardless of the embankment height. However, regain of strength and recovery of the arching effect was observable during further stages of cyclic loadings. Inclusion of reinforcement layers was found to enhance the performance of load transfer mechanisms. The surface settlement increased with raising the embankment height and reduced with increasing the number of reinforcement layers. Two preliminary experimental studies have been carried out in order to be able to understand and design the main experiment. The results showed that with increasing number of reinforcement layers, enormous cycles of loading could be applied without experiencing excessive deformation or loss of bearing resistance. Furthermore, it was observed that alternating the direction of movement significantly affected the formation of arching during the initial cycles irrespective of the embankment height. / Higher Education Institute of the Libyan Government

The increasing need for regional development has led engineers to find safe ways to construct the infrastructure of transportation on soft soils. Soft soil is not able to sustain external loads without having large deformations. The geotechnical properties of soft soil which is known for its low bearing capacity, high water content, high compressibility and long term settlement as well. In pavement engineering, either highway or runway as an infrastructure, a pavement encompasses three important parts namely traffic load, pavement and subgrade. Traffic load generated from tire pressure of vehicle and/or airplane wheels are usually around 550 kPa even more on the surface of the pavement. Pavement generally comprises granular materials with unbounded or bounded materials located between traffic load and subgrade, distributing the load to surface of subgrade. One of the promising soil improvement techniques is a piled embankment. When geosynthetics layer is unrolled over piles, it is known as geosynthetics supported piled embankment. Particularly in deep soft soil, when piles do not reach a hard stratum due to large thickness of the soft soil, the construction is an embankment on floating piles. Furthermore, because of different stiffness between piles and subsoil, soil arching effect would be developed there. By using Finite Element analysis, some findings resulted from experimental works and several field tests around the world as field case studies are verified. Some important findings are as follows: the stress concentration ratio is not a single value, but it would be changed depending on the height of embankment, consolidation process of subsoil, surcharge of traffic load, and tensile modulus of geosynthetics as well. Ratio height of embankment to clear piles spacing (h/s) around 1.4 can be used as a critical value to distinguish between low embankment and high embankment. When geosynthetics is applied to reinforce a pavement/embankment, the vertical distance of geosynthetics layers and number of geosynthetics layers depend on the quality of pavement material. The lower layer of geosynthetics withstands a tensile stress higher than upper layer. Primary reinforcements for geosynthetics in piled embankments are located at span between piles with maximum strains at zones of adjacent piles. Traffic load that passes through on the surface of the pavement can reduce the soil arching, but it can be restored during the off peak hours. Settlements of embankments on floating piles can accurately be modelled using the consolidation calculation type, whereas the end-bearing piles may be used the plastic calculation type. Longer piles can be effectively applied to reduce a creep. By applying length of floating piles more than 20% of soft soil depth, it would have a significant impact to reduce a creep on a deep soft soil.

The increasing need for regional development has led engineers to find safe ways to construct the infrastructure of transportation on soft soils. Soft soil is not able to sustain external loads without having large deformations. The geotechnical properties of soft soil which is known for its low bearing capacity, high water content, high compressibility and long term settlement as well. In pavement engineering, either highway or runway as an infrastructure, a pavement encompasses three important parts namely traffic load, pavement and subgrade. Traffic load generated from tire pressure of vehicle and/or airplane wheels are usually around 550 kPa even more on the surface of the pavement. Pavement generally comprises granular materials with unbounded or bounded materials located between traffic load and subgrade, distributing the load to surface of subgrade. One of the promising soil improvement techniques is a piled embankment. When geosynthetics layer is unrolled over piles, it is known as geosynthetics supported piled embankment. Particularly in deep soft soil, when piles do not reach a hard stratum due to large thickness of the soft soil, the construction is an embankment on floating piles. Furthermore, because of different stiffness between piles and subsoil, soil arching effect would be developed there. By using Finite Element analysis, some findings resulted from experimental works and several field tests around the world as field case studies are verified. Some important findings are as follows: the stress concentration ratio is not a single value, but it would be changed depending on the height of embankment, consolidation process of subsoil, surcharge of traffic load, and tensile modulus of geosynthetics as well. Ratio height of embankment to clear piles spacing (h/s) around 1.4 can be used as a critical value to distinguish between low embankment and high embankment. When geosynthetics is applied to reinforce a pavement/embankment, the vertical distance of geosynthetics layers and number of geosynthetics layers depend on the quality of pavement material. The lower layer of geosynthetics withstands a tensile stress higher than upper layer. Primary reinforcements for geosynthetics in piled embankments are located at span between piles with maximum strains at zones of adjacent piles. Traffic load that passes through on the surface of the pavement can reduce the soil arching, but it can be restored during the off peak hours. Settlements of embankments on floating piles can accurately be modelled using the consolidation calculation type, whereas the end-bearing piles may be used the plastic calculation type. Longer piles can be effectively applied to reduce a creep. By applying length of floating piles more than 20% of soft soil depth, it would have a significant impact to reduce a creep on a deep soft soil.