• Geomechanics and Engineering
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• v.27 no.6
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• pp.561-571
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• 2021

Cofferdams made of teel sheet piles are commonly utilized as support structures for excavation of sea-crossing bridge foundations. As cofferdams are often subject to tide variation, it is imperative to consider potential effects of tide on stability and serviceability of sheet piles, particularly, ultralong steel sheet piles (USSPs). In this study, a real USSP cofferdam constructed using new construction technology in Nanxi River was reported. The design of key parts of USSP cofferdam in the presence of tidal action was first introduced followed by the description of entire construction technology and associated monitoring results. Subsequently, a three-dimensional finite-element model corresponding to all construction steps was established to back-analyze measured deflection of USSPs. Finally, a series of parametric studies was carried out to investigate effects of tide level, soil parameters, support stiffness and construction sequence on lateral deflection of USSPs. Monitoring results indicate that the maximum deflection during construction occurred near the riverbed. In addition, measured stress of USSPs showed that stability of USSP cofferdam strengthened as construction stages proceeded. Moreover, the numerical back-analysis demonstrated that the USSP cofferdam fulfilled the safety requirements for construction under tidal action. The maximum deflection of USSPs subject to high tide was only 13.57 mm at a depth of -4 m. Sensitivity analyses results showed that the design of USSP cofferdam system must be further improved for construction in cohesionless soils. Furthermore, the 5th strut level before concreting played an indispensable role in controlling lateral deflection of USSPs. It was also observed that pumping out water before concreting base slab could greatly simplify and benefit construction program. On the other hand, the simplification in construction procedures could induce seepage inside the cofferdam, which additionally increased the deflection of USSPs by 10 mm on average.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.789-796
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• 2003

A reliability analysis is performed to investigate the influence of the uncertainty from the limited in-situ samples and the inherent heterogeneity of the ground on the probability of piping for the marine embankment near shore. The result are compared with those of the deterministic piping stability analysis performed using the fininte element flow analysis. The random variables used are hydraulic conductivity of the ground subsurface and embankment, and the water level of both internal and external side of the embankment. The probability of piping is most sensitive to the mean and standard deviation of internal water level of the embankment among the random variables included in the reliability analysis. It is found that the lower limits of internal water level which satisfies the allowable proability of piping failure for the embankment studied were E.L(-) 1.83m and E.L(-) 1.48m during and after the construction of the embankment, respectively.

• Journal of the Korean Geotechnical Society
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• v.27 no.4
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• pp.33-41
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• 2011

A railway embankment route extending to 2 km was laid on normally consolidated clay in the West Gimhae Plain. This embankment was first built using the stage-construction technique, but longitudinal cracks suggesting arc sliding appeared on the surface of the embankment immediately after the first stage of its construction. As an alternative, the piled raft was installed on the failed embankment and then the remaining height of the embankment was raised. The behavior of the piled raft was monitored with different instruments during construction. This paper describes the monitoring results and analyses. The results show that if the pile group essentially exhibits the behavior of friction piles, the piled raft foundation performs well even in normally consolidated soft clay.

• Geomechanics and Engineering
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• v.7 no.1
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• pp.105-131
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• 2014

In this paper, the effects of variability of smear zone characteristics induced by installation of prefabricated vertical drains on the preloading design are investigated employing analytical and numerical approaches. Conventional radial consolidation theory has been adopted to conduct analytical parametric studies considering variations of smear zone permeability and extent. FLAC 2D finite difference software has been employed to conduct the numerical simulations. The finite difference analyses have been verified using three case studies including two embankments and a large-scale laboratory consolidometer with a central geosynthetic vertical drain. A comprehensive numerical parametric study is conducted to investigate the influence of smear zone permeability and extent on the model predictions. Furthermore, the construction of the trial embankment is recommended as a reliable solution to estimate accurate smear zone properties and minimise the post construction settlement. A back-calculation procedure is employed to determine the minimum required waiting time after construction of the trial embankment to predict the smear zone characteristics precisely. Results of this study indicate that the accurate smear zone permeability and extent can be back-calculated when 30% degree of consolidation is obtained after construction of the trial embankment.

• Geomechanics and Engineering
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• v.1 no.3
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• pp.193-204
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• 2009

A 10.4-m high highway embankment retained behind mechanically stabilized earth (MSE) walls is under construction in the northeastern part of the Indian state of Bihar. The structure is constructed with compacted, micaceous, grey, silty sand, reinforced with polyester (PET) geogrids, and faced with reinforced cement concrete fascia panels. The connections between the fascia panels and the geogrids failed on several occasions during the monsoon seasons of 2007 and 2008 following episodes of heavy rainfall, when the embankment was still under construction. However, during these incidents the MSE embankment itself remained by and large stable and the collateral damages were minimal. The observational data during these incidents presented an opportunity to develop and calibrate a simple procedure for estimating rainfall induced pore water pressure development within MSE embankments constructed with backfill materials that do not allow unimpeded seepage. A simple analytical finite element model was developed for the purpose. The modeling results were found to agree with the observational and meteorological records from the site. These results also indicated that the threshold rainwater infiltration flux needed for the development of pore water pressure within an MSE embankment is a monotonically increasing function of the hydraulic conductivity of backfill. Specifically for the MSE embankment upon which this study is based, the analytical results indicated that the instabilities could have been avoided by having in place a chimney drain immediately behind the fascia panels.

• Journal of the Korean Society for Railway
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• v.10 no.5
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• pp.457-462
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• 2007

An application of concrete track is being activity processed for the construction of Korean railroad. The concrete track has an advantage to decrease the maintenance fee, but is very difficult to control the settlement of ground and embankment consisting of substructure of concrete track below the allowable settlement level. This is the reason why the measurement and evaluation of both ground and embankment settlement before the installation of the concrete track is very important. One ground, a lower subgrade, and five surface settlements are measured to understand the settlement behavior of ground and embankment settlement. The period to measure settlements was more than 1 year after the completion of embankment. In this test site, ground settlement was over during the construction of embankment, but the embankment settlement are being continuously proceeded after the completion of embankment. The settlement velocity gradually is slowing down as time goes by. This paper also analysed the reasons of abrupt settlement increase and concluded that the rainfall was one of the important reason to increase settlement rate.

• Water for future
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• v.6 no.2
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• pp.12-18
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• 1973

This paper describes the study and test for sand and gravel embankment in winter season and also contribute to the development of construction method for the practical purposes. In order to make possible sand and gravel embankment in winter season, at first, the following eriteria on work are given under the normal weather condition: 1) The maximum diameter of material shall not exceed 30cm and sand content which is the ratio of the weight of sand to gravel shall not exceed 60% 2) Spreading depth shall not exceed 60cm each layer of material shall be compacted by over 6 times passing by thell ton smooth drum type of uibratory roller and the relative density shall exceed 60% In addition to the above conditions, the following criteria are given as winter season condition. 3) Sand contsnt shall not exceed 25%, and water content shall not exceed 4% 4) Dwing construction, the air temperature should be $70^{\circ}C$ below zero at minimum and $3^{\circ}C$ below zero onthe average and all the construction work should he continued without intersuptions. With above criteria, it is come to a conclusion that the conclusion that the construction of sand and gravel embankment in winter season will be done satisfactorily without any difficulty. On the basis of these criteria an actual construction was practiced and it was proved that those criteria are applicable to actual embankment of materials.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1094-1101
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• 2005

The stability of embankment on the soft ground has included problems on stabilities of embanked body and soft soil, which related with vertical displacement and lateral movement of the soft ground especially. The judge methods for the potentialities of lateral movement have been used in order to stabilization assessment during and after construction of the embankment. In this study, the judge methods on the improved soft ground suggested, which compared with exist judge methods on lateral movement. It is due to recent trend using embanked structures on the soft ground most of improved.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.02a
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• pp.79-92
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• 2000

In this paper, comparison of the observed and the predicted ground deformations due to the construction of road embankment with peck drain near the construction site was made. Measurement of the ground deformation at the gasoline stand due to the construction of road embankment was made and it was compared with the predicted deformation results of Finite Element Method analysis made with Elasto-plastic and Elastic visco-plastic models. A well agreement was obtained between the measured and predicted ground deformations.

• Journal of the Korean Geosynthetics Society
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• v.9 no.4
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• pp.27-37
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• 2010

Woven geotextiles (polyester mats) reinforcement is generally used to improve traffic ability, bearing capacity, and slope stability for embankment construction on soft ground. Cases of two high-strength woven geotextiles reinforcement layers are introduced in the present paper, which has been successfully constructed for rail road embankment on soft ground. According to the case results based on the limit equilibrium analyses of slope stability, the two high-strength woven geotextiles reinforcement layers on the soft ground can substantially increase the stability of the embankment by about 25%, improve the safety factor from 0.91 to 1.14, and significantly reduce the embankment construction duration at least 2 months. Therefore, the application of high-strength woven geotextiles is found to be useful for in-situ cases having the lack of construction duration and stability, as a soft ground improvement.