• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1489-1493
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• 2009

The disaster with many casualties every year by floods, and the economic loss will occur in Korea. The establishment and the recovery measures are necessary. In this research, we analyzed the effect for reducing flood by making washland in flood season, where is used as the wetland in non-flood season in Hwapocheon basin of Nakdong River, Korea. We prepared draingage of inner basin for flood in the past because the water elevation of Hwapocheon is lower than the water elevation of the Nakdong River. On the other hand, now a days, drainage capacity of the expansion and change of the height of the embankment have limitations, because of the increase in torrential rains. In this study, HEC-RAS is used for the unsteady flow routing for the effectiveness analysis of flood level mitigation in flood season. This analysis was performed according to the scenarios of washland construction location and its scale.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.35-44
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• 2020

Design techniques for the deep mixing method, one of the soft ground improvement methods, include two ways to interpret the ground as composite ground and pile ground. However, since comparative studies on these two approaches are insufficient, it is difficult to clearly define the analysis criteria in the design. In this study, two-dimensional and three-dimensional analyses have been performed with different conditions. The three conditions, the embankment height, depth of soft ground, and replacement ratio of reinforcement zones were varied and the analysis was performed on the basis of the assumption of composite ground and pile ground for each condition. As a result, the minimum depth of improvement in the two-dimensional analysis was deeper by 6.85~9.08% than in the three-dimensional analysis. The pile ground analysis showed that the depth of improvement was deeper by 12.22~14.45% than the composite ground analysis. Based on these results, it is concluded that for more accurate design, three-dimensional analysis should be performed rather than two-dimensional analysis. also, it is judged that necessary to analyze the ground as composite ground for economical design, and as the pile ground analysis for stable design.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.27-35
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• 2002

To construct pipe lines, culverts, or other utility lines, temporary slopes formed by excavating the compacted embankment are frequently met with in the field. Ignoring stability analyses for such slopes and applying inappropriate slope inclinations often result in safety problems. In this study, stability of such slopes were investigated considering the influence of anisotropic shear strength of the layered compacted ground. A series of stability analyses were conducted for slopes varying the slope angle and the height, and assuming isotropic and anisotropic shear strength conditions, respectively. The anisotropic shear strength of the compacted soil was determined from the direct shear test for layered soil blocks varying the inclination angle between the horizontal shear surface and the direction of the soil layer. As a result of the analyses, it has been concluded that the appropriate slope inclination f3r a temporary slope could vary in accordance with the consideration of anisotropy. However, the factor of safety as well as the location of the failure surface did not show significant variation.

• Journal of the Korean Society for Railway
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• v.20 no.2
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• pp.248-256
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• 2017

Groundwater drawdown was pointed out as one of the causes of induced settlement on high speed railways, especially concrete track. In this study, the effect of groundwater variation on settlement was evaluated through a comparison of field measurements with numerical analysis results. A trial and error method, i.e., repeated numerical analyses by changing material properties, was used to calibrate the model. The model was applied to investigate the effect of groundwater drawdown, thickness of soft layer, and embankment height on residual settlement after concrete track completion. A soft layer thicker than 4m would result in more than 30mm of settlement; a detailed analysis of groundwater behavior thus should be conducted from the design stage to construction.

• Journal of the Korean Geosynthetics Society
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• v.18 no.3
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• pp.55-67
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• 2019

Deep soft ground in mouth of Nackdong river requires to be analysed with prediction method concerning characteristics of secondary consolidation from the beginning because it causes excessive settlement due to time-dependant secondary consolidation characteristics. This study investigated characteristics of extended settlement by conducting one-dimensional theory, elasto-plastic model and visco-elasto-plastic model as well as analyzing long-term measuring data observed over 2,000 days. According to one-dimensional theory and elasto-plastic model, there is not definite correlation between height of embankment and depth of soft ground while visco-elasto-plastic model showed similar result of settlement to that of long-term measuring data. Consequently it is suggested that applying visco-elasto-plastic model to developing deep underground place as studied area on predicting extended settlement before construction prevents economic loss and delay during process by preparing secondary consolidation characteristics.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.1
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• pp.173-178
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• 2020

A multi-ray model has been used to interpret radio transmission losses in half-canyon structures with slope and to formulate a multi-ray propagation model depending on the angle of slopes. The cut-off angles for the third and fourth paths, which are the slope-sided reflection paths of the transmission and reception radio waves determined by the inclined angles of the slope, were calculated with the height and location of the transmitter and receiver. To predict transmission losses in an inclined plane environment, the embankment environment where the actual slope exists was modeled and simulated to calculate the loss of propagation transmission, and the radio wave transmission loss was confirmed by the measurement for the frequency band 1 to 6 GHz. Simulation results and measurement results showed similar trends in radio transmission loss, and radio transmission loss predictions and measurement results for various terrain information can be used in the design of radio propagation service.

• Journal of the Korean Geotechnical Society
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• v.24 no.9
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• pp.33-40
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• 2008

This paper describes the performance of ground improvement project using prefabricated vertical drains of condition, in which approximately 10m dredged fill overlies original soft foundation layer in the coastal area composed of soft marine clay with high water content and high compressibility. From field monitoring results, excessive ground settlement compared with predicted settlement in design stage developed during the following one year. In order to predict the final consolidation behavior, recalculation of consolidation settlements and back analysis using observed settlements were conducted. Field monitoring results of surface settlements were evaluated, and then corrected because large shear deformation occurred by construction events in the early stages of consolidation. To predict the consolidation behavior, material functions and in-situ conditions from laboratory consolidation test were re-analyzed. Using these results, height of additional embankment is estimated to satisfy residual settlement limit and maintain an adequate ground elevation. The recalculated time-settlement curve has been compared with field monitoring results after additional surcharge was applied. It might be used for verification of recalculated results.

• Journal of the Korean GEO-environmental Society
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• v.16 no.2
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• pp.53-58
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• 2015

The Pre-loading method has been widely used for the soft ground stabilization but long construction times and the transport of large quantities of fill material are required. To shorten the construction periods, the vertical drain method is generally applied simultaneously. But the high costs of the fill materials along with environmental damages remain as the main difficulties to apply this method. Therefore, a complimentary way to reduce both the height of the embankment and the consolidation time is needed. In this study, the electro-osmosis method, which is able to shorten the consolidation time and minimize the damage of the environment, was performed with a model test. The results show that as the voltage increases the consolidation settlements, consolidation drainage and shear strength also increase while the water content decreases.

• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.217-225
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• 2023

This study analyzed the effect of flood level reduction in the case of creating and operating offline storage for the Jangdong district, which can be used as a flood buffer space for the Geumgang River, through one-dimensional unsteady flow numerical simulation. In particular, the sensitivity analysis of changes in the height and width (length) of transverse weirs on flood level changes was performed to provide quantitative information necessary for flood control facility (embankment) design. As a result of analyzing the flood control effect of the offline storage based on the peak flood discharge and level, spatially, the flood control effect at the planned flood buffer space site and the downstream end was confirmed, and it was confirmed that the flood reduction effect at the downstream occurred the most. By design conditions of the transverse overflow weir, the greatest flood reduction effect was found under the condition that the overflow weir height based on the 50-year frequency flood level and the transverse overflow weir width (length) of 125 m were considered. The effect of delaying the time to reach the maximum flood due to the operation of the offline storage site was also presented based on unsteady flow modeling.

• Journal of the Korean Geosynthetics Society
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• v.22 no.1
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• pp.87-96
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• 2023

There are a lot of difference between the surface settlement and the differential settlement measured at the Busan New Port, where the dredged and reclaimed clay layer exists and below the clay is originally thickly distributed. To find the cause and solution of this, the actual conditions of each differential settlement used for the soft ground improvement, characteristics, installation method, measurement frequency, measurement data management, and data analysis of each type were considered. In the deep soft ground improvement work where large deformation occurs, the bending deformation of the screw-type differential settlement gauge is less than that of other types of measuring instruments, so there is less risk of loss, and the reliability of data is relatively high as the instruments are installed by drilling for each stratum. Since the greater the amount of high-precision settlement measurement data, the higher the settlement analysis precision. It is necessary to manage with higher criteria than the measurement frequency suggested in the standard specification. For the data management of the differential settlement gauge, it is desirable to create graphs of the settlement and embankment height of the relevant section over time, such as surface, differential, and settlement of pore water pressure gauge for each point. In the case of multi-layered ground with different compression characteristics, it is more appropriate to perform settlement analysis by calculating the consolidation characteristics of each stratum using a differential settlement data.