• Geomechanics and Engineering
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• v.6 no.1
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• pp.17-31
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• 2014

This paper investigates the development of failure surfaces induced by an embankment on soft marine clay deposits and the characteristics of such surfaces through numerical simulations and its comparative study with monitoring results. It is well known that the factor of safety of embankment slopes is closely related to the vertical loading, including the height of the embankment. That is, an increase in the embankment height reduces the factor of safety. However, few studies have examined the relationship between the lateral movement of soft soil beneath the embankment and the factor of safety. In addition, no study has investigated the distribution of the pore pressure coefficient B value along the failure surface. This paper conducts a continuum analysis using finite difference methods to characterize the development of failure surfaces during embankment construction on soft marine clay deposits. The results of the continuum analysis for failure surfaces, stress, displacement, and the factor of safety can be used for the management of embankment construction. In failure mechanism, it has been validated that a large shear displacement causes change of stress and pore pressure along the failure surface. In addition, the pore pressure coefficient B value decreases along the failure surface as the embankment height increases. This means that the rate of change in stress is higher than that in pore pressure.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.862-870
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• 2010

This thesis has been researched on optimized design method for the total cross section of embankment considering the fact that the size of embankment cross section is directly related with economic efficiency when dam designing. In general, embankment cross section of fill dam is either determined by cohesion and angle of internal friction, a strength parameter of embankment materials or by permeability of embankment. Therefore the size of embankment cross section depending on strength parameter of embankment materials was determined by using MIDAS-GTS program through stress-seepage coupled analysis at the time of fill dam design. As a result, determination of embankment cross section was more affected by the size of central core and permeability rather than by slope stability by shear strength and it was revealed that in case of embankment height being over 20m, stability against infiltration and slope action could be secured only when embankment slope is at least over 1:2.5. In addition, it was also revealed that in case of making the size of central core exceeding specification standard, total cross section of embankment could be reduced considerably and at the time of embankment design, adequate size and appropriateness of embankment cross section could be determined with referring the table suggested by this study.

• Structural Engineering and Mechanics
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• v.56 no.4
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• pp.507-534
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• 2015

The present work investigates the behavior of the embankment models resting on soft soil reinforced with ordinary and stone columns encased with geogrid. Model tests were performed with different spacing distances between stone columns and two lengths to diameter ratios (L/d) of the stone columns, in addition to different embankment heights. A total number of 42 model tests were carried out on a soil with undrianed shear strength $${\sim_\sim}10kPa$$. The models consist of stone columns embankment at s/d equal to 2.5, 3 and 4 with L/d ratio equal 5 and 8. Three embankment heights; 200 mm, 250 mm and 300 mm were tested for both tests of ordinary (OSC) and geogrid encased stone columns (ESC). Three earth pressure cells were used to measure directly the vertical effective stress on column at the top of the middle stone column under the center line of embankment and on the edge stone column for all models while the third cell was placed at the base of embankment between two columns to measure the vertical effective stress in soft soil directly. The performance of stone columns embankments relies upon the ability of the granular embankment material to arch over the 'gaps' between the stone columns spacing. The results showed that the ratio of the embankment height to the clear spacing between columns (h/s-d) is a key parameter. It is found that (h/s-d)<1.2 and 1.4 for OSC and ESC, respectively; (h is the embankment height, s is the spacing between columns and d is the diameter of stone columns), no effect of arching is pronounced, the settlement at the surface of the embankment is very large, and the stress acting on the subsoil is virtually unmodified from the nominal overburden stress. When $(h/s-d){\geq}2.2$ for OSC and ESC respectively, full arching will occur and minimum stress on subsoil between stone columns will act, so the range of critical embankment height will be 1.2 (h/sd) to 2.2 (h/s-d) for both OSC and ESC models.

• Journal of The Geomorphological Association of Korea
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• v.21 no.4
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• pp.165-180
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• 2014

Embankment of reservoir Gonggeomji in Sangju has been continuously added since the construction. After approximately 1220 yr BP of late Unified Silla dynasty when the embankment was firstly constructed, there were piled up four times with an interval of approximately 50 years until ca. 980 yr BP of late Goryeo dynasty. The first two times were relatively piled up high, while another two times were made slightly high. After addition of embankment, water level gradually became low and the quality also bad with increase of benthic- and epipitic diatoms than planktonic ones. Shoaling of reservoir was probably resulted from severe vegetation destructions on the small river basins flowing into Gonggeomji. After approximately 980 yr BP, water level rose during approximately 50 years due to precipitation increase.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1253-1263
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• 1994

The stability of the embankment is depended upon the location of seepage line. As the seepage flow occurs in the embankment, the slope of the embankment loses its stability. Of particular interest is the stability following a rapid change of embankment level. The variation of seepage line in the embankment model according to flow velocity was investigated. In addition to this non-steady state flow in embankment by a fluctuation of water level is discussed. The experimental model was construction with slopes of 1 : 2.5 and flow velocity is turned from 60 cm/sec~90 cm/sec. Analysis of the experimental results, the seepage line is influenced by flow velocity and coefficient of permeability.

• International Journal of Highway Engineering
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• v.10 no.3
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• pp.109-118
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• 2008

This study analyzes the change of stability of embankment due to the construction of embankment combined used road with two different construction phases. The stabilities have been checked both in the phase of earth banking for a road construction and in the phase of the application of the traffic roads(DB-24). In both cases the factor of safety has been found higher than 1.3 which is the general criterion of the safety of an embankment. The results indicate that the safety of an embankment due to the construction of embankment combined use road is assured, and thus, it is thought that the construction of embankment combined use road can be considered for cutting down on expenses of construction sites for a road construction. However, the pre-examination of stability due to the construction should be carried out because it decreases the factor of safety of an embankment. From this study, it has been found that the factor of safety was dropped most when the water level rose in the transient flow. The result indicates that the stability analysis of a river embankment where the water level changes frequently should be carried out in the condition of transient flow. It is recommended that the inner side of an embankment should have a slope of 1:2 which is identical with the slope of the existing embankment. In addition, the factor of safety also can be decreased due to the traffic loads, and therefore, the effect should also be considered after the construction of embankment combined used road limiting the traffic loads.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.891-898
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• 2009

A high rock embankment by means of dynamic compaction has hardly carried out in domestic area. For the successful accomplishment of such a high rock embankment, construction quality and measurement control are conducted. Plate loading tests are carried out to verify the bearing capacity and safety against the long term settlement. In addition, settlement of each layer is measured in order to verify the effect of dynamic compaction and to predict long term settlement.

• The Korean Journal of Ecology
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• v.26 no.3
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• pp.103-108
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• 2003

This study examined the coastal sand dune vegetation before and after the construction of an embankment on Anmado Island in order to compare vegetation in relation to the development of islands. A total of 24 species distributed on the sand dunes. 18 species were found to be in common before and after the construction of the embankment, which included Vitex rotundifolia, Imperata cylindrica var. koenigii, Zoysia sinica, etc. The species which were not found in this survey included Rumex japonicus, Setaria viridis, Portulaca oleracea, Artemisia japonica, Poiygonum aviculare, etc, and new species included Arena fatua, Carex boottiana, Lycium chinense, Leonurus sibiricus, Torilis japonica, Solanum carolinense, etc. The washing away of sand brought about the changes in habitat and the increase in naturalized plants, which included Oenothera odorata, Lepidium apetalum, Bidens bipinnata, Erigeron canadensis, Datura stramonium, Xanthium strumarium, Arena fatua, Solanum carolinense etc. In addition, the disturbance to this habitat led to the changes in vegetation. The main plant communities in the surveyed site were classified as Vitex rotundifolia-Imperata cylindrica var. koenigil community, Zoysia sinica-Calystegia soldanella community and Messerschmidia sibirica community. The sand dune vegetation on Anmado Island changed with regard to the community and the composition of species after the construction of the embankment, due to the sand being severely eroded. While Vitex rotundifolia community and Commelina communis community were found before the construction of the embankment, they were replaced by Vitex rotundifolia-Imperata cylindrica var. koenigii community, Zoysia sinica-Calystegia soldanella community and Messerschmidia sibirica community, after the construction of the embankment.

• Journal of the Korean Geotechnical Society
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• v.25 no.5
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• pp.17-28
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• 2009

When embankments are constructed on soft clay deposit, unsymmetrical surcharges due to embankments may generate the excessive vertical settlement and lateral deformation of soft clay foundation. The excessive deformations in soft grounds cause not only stability problem of the embankment itself but also that of the adjacent structures. The objectives of this research are to study the deformational behavior of soft ground due to the embankment load with different loading and soil conditions. Five model tests are carried out with different test conditions. From the results of the model tests, it is concluded that the lateral displacement induced by the embankment load occurs in the range of two times of the embankment width from a toe. In addition, the relationship between loading rate, v, and the vertical settlement of the soft ground, ${\Delta}s$, and the lateral displacement at the toe of embankment, ${\Delta}y_m$, is investigated based on the model test results.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.967-975
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• 2009

In order to control differential settlement and to secure the safety of super structure on a high rock embankment the designed static compaction is changed with dynamic compaction and piled raft method. The parameters for dynamic compaction design are obtained from a pilot test. In addition, numerical analyses are also carried out to figure out the length and quantity of piled raft that can restraint the differential settlement within allowance range.