• Geotechnical Engineering
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• v.12 no.4
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• pp.131-144
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• 1996

In order to accelerate the rate of consolidation settlement and to gain a required shear strength for a given soft clay deposit, the preloadina technique combined with a vertical drainage system has been widely applied. Even if a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits, the actual field behavior is often different from the behavior predicted in the design state due to several uncertainties involved in soil properties, numerical modelling, and measuring system. In this paper, two back-analysis schemes such hs simplex and BFGS methods have been implemented in an a Bisymmetric consolidation program, AXICON which considers the variation of compressibility and permeability during the consolidation process. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of drainage-installed soft deposits.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.11c
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• pp.169-178
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• 1999

본 논문에서는 실내에서 실시한 Filtration실험을 통하여 지하수 흐름하에서 이탈한 풍화 잔류토의 세립자가 흙-토목섬유 복합체를 통과하면서 발생하는 이동 (Transportation), 퇴적 (Deposition), 그리고 폐색 (Clogging)되는 과정을 분석하였다. 본 연구에서는 한국의 풍화 잔류토에 적합한 토목섬유 배수재의 새로운 설계기준을 제시함으로써 풍화 잔류토상에 축조되는 터널 구조물 시공시 광범위하게 사용되고 있는 토목섬유재인 부직포의 투수 및 배수특성과 세립토사에 의한 폐색 (Clogging)영향을 분석할 수 있게 되었다.

• Geotechnical Engineering
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• v.12 no.1
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• pp.5-20
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• 1996

In order to accelerate the rate of consolidation settlement and to gain a required shear strength for a given soft clay deposit, the preloading technique combined with a vertical drainage system has been widely applied. In this'study, the theory of axisymmetric consolidation which considers the variation of compressibility and permeability during the conslidation process, has ben developed. A computer program named AXICON for the analysis of axisymmetric nonlinear consolidation is developed by adopting an explicit finite difference method. Smear and well resistance effects are also considered. The AXICON is capable of analyzing the consolidation behavior of multi -layered deposits and simulates time dependent loading sequence. The results of AXICON are validated with analytical solutions of Hansbo and Barron, and compared with insitu settlements and pore pressures measured in a soft clay deposit.

• Journal of the Korean GEO-environmental Society
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• v.24 no.11
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• pp.25-31
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• 2023

Horizontal drainage, which are representative dewatering method of domestic and foreign slope, are applied to reducing pore water pressure. Accordingly, several previous studies have been conducted, but horizontal drainage are standardized which is an unclean standard for a quantity calculation in filed. Therefore, this study presents field soil and laboratory model box to identify a drainage performance and influencing factors of various horizontal drainage. Furthermore, this study verifies the performance comparison of drainage shape or size according to different particle size distributions. In the outflow results for steady state, the study found that all samples are drained at a constant rate after a minimum of 3 minutes to maximum of 15 minutes. In the case of comparing the outflow per hour (Unit flux) in coarse grained soils, it found that drainage shape and size affect drainage performance. In the result, the future expected to be used basic data that experiment of drainage performance on fine grained soils and determine the quantity.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.03a
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• pp.3-14
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• 1995

• Journal of the Korean Geosynthetics Society
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• v.12 no.1
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• pp.29-38
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• 2013

This paper presents the analysis condition of remediation technique of contaminated fine-grained soil and physical properties of bio-degradable drain for analysis site applicability using bio-degradable drain method. As the result, two kinds of developed degradable drains (cylindricality shaped and harmonica shaped) are satisfied the Korean Industrial Standard. And the cylindricality shaped drain has an excellent discharge capacity than that of another one. By the results of laboratory test, the citric acid is chosen as the washing agent because it has low toxicity, so it is able to minimize harmful influence to environment. Furthermore the subject contaminants were selected as Cd, Cu and Pb. Based on the field pilot test results, the most remedial efficiency is the use of reactive material applied in bio-degradable drain method with the process of injecting the washing agent and extraction of contaminated fluid.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.27-39
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• 2005

A finite difference program with 3-D governing equation expanded from 1-D self-weight consolidation is developed to analyze the consolidation behavior of surface dredged soil with horizontal drains. Various boundary conditions with horizontal drains and seepage pressure of pore water infiltrated to the drains are considered in the program. A laboratory soil chamber experiment for the consolidation of dredged soil is performed to validate the program and the measured settlement-time result is compared with the one predicted by the program. The influence of design conditions of horizontal drains such as horizontal installation spacing, installation depth and number of drain layers, on the consolidation is analyzed.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.43-50
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• 2000

In this paper, the consolidation efficiency and the equivalent diameter of the cross shaped drain are examined by using the laboratory test and the numerical model, and the results are compared with those of the band shaped drain. The equivalent diameter of the tested drains is back-calculated from the laboratory experiment and compared with those calculated from the formula suggested in the literature. The efficiency of the cross shaped drain is evaluated by using the 3-D flow program which was validated by the settlement-time test fill data. The results of laboratory test show that the equivalent diameter of the band shaped drain was close to the Rixner's formula and that of the cross shaped drain was fit to the following formula: $d_w\;=\; \\tarc{3}{4}.(b+t)$The results of the numerical analysis show that the cross shaped drain can reduce the consolidation time by 9-10% from that for the band shaped drain. The equivalent diameter obtained from the numerical flow model by using the field data is 3.5 times smaller than that obtained from the laboratory consolidation test.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.87-96
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• 2014

In this paper, reliability analysis was done on the characteristics of consolidation and settlement for the inner temporary dike where a weak ground improvement construction was applied. When the consolidation analysis on the foundation ground was done, the following conclusions were obtained by conducting the stability analysis on the effect of space of drains, the effect of consolidation time, and the residual settlement and differential settlement. When construction was done with a drain space which satisfied 95% probability of reaching a target consolidation in each divided area, the occurrence of a residual settlement was within the range, which did not exceed 10cm. It was shown that there was almost no possibility of the occurrence of differential settlement, which was above the permissible differential settlement slope.

• Journal of the Korean GEO-environmental Society
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• v.10 no.6
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• pp.69-77
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• 2009

The shortage of bearing capacity and settlement, shear deformation may occur when constructing a structure such as harbor, airport and bridge on soft ground such as marine clay, silty clay, sandy soil because it is very soft. The various ground improvement methods were applied to obtain preceding settlement of soft ground and strength increase. The vertical drain method has been used to reduce the required time for consolidation of the soft ground. Especially, the PBD (Plastic Board Drain) has been widely used among in the vertical drain method. In this study, a behavior of characteristic was evaluated by operating a compound drainage capacity test about the PBD (Plastic Board Drain) method applied in soft clay in deep depth. As a result, the settlement gradually occurred with increase of surface load. The consolidation settlement was processed with dissipation of pore pressure after surface load of $500kN/m^2$. Accordingly, it was found that change of settlement through load steps was resulted from dissipation of pore pressure. It was also found that the drainage capacity of vertical drains was considerably reduced with pressure increase and time elapse.