• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.1030-1035
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• 2008

Dynamic numerical analyses were performed to investigate the response of liquefaction remediation of rammed aggregate piers(RAP) on soft ground under free strain conditions. The safe factors of the soft ground reinforced by RAP during seismic loading of magnitude 6.5 were calculated. The results of simulation showed that factors of safety were affected various area replacement ratios, surcharge loads and depth of RAP systems.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1678-1688
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• 2008

In this study, dredging reclamation ground were performed to evaluate the ground improvement and liquefaction reduction effect with the result that standard penetration test(SPT) and piezo penetration test(CPT) before and after of improvement. Especially, the estimate center of the pile and factor of liquefaction safety to the position of ground around with the pile presented improvement of compaction for improved compaction of dredging reclamation ground.

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1071-1076
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• 2004

The purpose. in this study. is to analyze liquefaction potential of Inchon International Airport at the Area Phase ' I ' for Railway Construction of all, seismic response was analyzed using the computer program, Shake91. Four methods proposed by Seed & Idriss. Eurocode, Iwasaki & Tatsuoka. and Ishihara were used for assessment of liquefaction potential and safety factors calculated form these methods are compared. Based on the results of seismic response analysis, the maximum acceleration at the ground surface is larger than that evaluated site factor effect by using site factor because these areas are composed of very loose sand clay. Especially, in the case of analysis with long period earthquake data. it is appeared that the acceleration of earthquake is amplified more largely. Therefore, accurate seismic response analysis is suggested for the design on the important structures on reclaimed land. The analytical results of liquefaction potential show that the increments of N-value and effective overburden pressure with remediation make safety factors increase. Through comparing the safety factors evaluated from four method, the safety factor calculated by See & Idriss method in the lowest one and it is found that the SPT N-value effect the safety factor very largely. And, Iwasaki & Tatsuoka method is affected by various factors such as average grain size. fine contents, confining pressure. In conclusion. to minimize earthquake Risk by liquefaction, the efficient remediation is essential and seismic response analysis should be carride out.

• Proceedings of the Korean Geotechical Society Conference
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• 1998.10a
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• pp.3-30
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• 1998

• Journal of the Korean GEO-environmental Society
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• v.7 no.6
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• pp.133-143
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• 2006

A fully coupled effective stress dynamic analysis procedure for modeling seismic liquefaction on slope is presented. An elasto-plastic formulation is used for the constitutive model UBCSAND in which the yield loci are radial lines of constant stress ratio and the flow rule is non-associated. This is incorporated into the 2D version of Fast Lagrangian Analysis of Continua (FLAC) by modifying the existing Mohr-Coulomb model. This numerical procedure is used to simulate centrifuge test data from the Rensselaer Polytechnic Institute (RPI). UBCSAND is first calibrated to cyclic direct simple shear tests performed on Nevada sand. Both pre- and post-liquefaction behaviour is captured. The centrifuge test is then modeled and the predicted accelerations, excess porewater pressures, and displacements are compared with the measurements. The results are shown to be in general agreement. The procedure is currently being used in the design of liquefaction remediation measures for a number of dam, bridge, tunnel, and pipeline projects in Western Canada.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.4C
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• pp.221-230
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• 2008

The George Massey immersed tunnel passes the Fraser River near Vancouver, Western Canada. The tunnel was founded on sandy soils and its behavior during earthquake was analyzed by an effective stress constitutive model called UBCSAND. This model is able to calculate pore pressure rise and resulting tunnel movements due to cyclic loading. Centrifuge tests conducted at Rensselaer Polytechnic Institute (RPI) were used to verify the model performance. The centrifuge tests consisted of 2 models: Model 1 was designed for an original ground condition, Model 2 for a ground improvement by densification. In Model 1, large deformation of the tunnel was observed due to liquefaction of surrounding soil. Because of the densified zones around the tunnel the vertical and horizontal displacements of the tunnel in Model 2 was 50% less than Model 1. Measured excess pore pressures, accelerations, and displacements from centrifuge tests were in close agreement with the predictions of UBCSAND model. Therefore, the model can be used to predict seismic behavior of immersed tunnels on sandy soils and optimize liquefaction remediation methods.

• Journal of the Korean Geotechnical Society
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• v.16 no.5
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• pp.75-81
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• 2000

본 연구에서는 진동대 시험을 실시하여 지진동에 대한 일반 안벽 구조물과 내진 보강된 안벽 구조물의 동적거동을 분석하고 내진보강기법의 성능을 평가하였다. 진동대 시험은 기초지반이 조밀한 경우와 느슨한 경우, 자갈 뒤채움재를 설치한 경우 그리고 내진대책공법으로 경량재 치환공법과 모래다짐말뚝 공법을 적용한 경우 등 총 5가지 시험단면에 대하여 실시하였다. 과잉간극수압, 가속도 반응 그리고 지반의 변형양상을 분석한 결과, 기초지반과 뒤채움 지반의 연약화가 안벽 구조물의 동적거동에 큰 영향을 미치며, 경량재 치환공법과 모래다짐말뚝공법이 안벽 구조물의 내진성능을 향상시키는에 효과적인 것으로 나타났다.