• Journal of the Earthquake Engineering Society of Korea
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• v.7 no.5
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• pp.37-46
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• 2003

Response analysis of buried pipeline subjected to permanent ground deformation(PGD) due to liquefaction is mainly executed by use of numerical analysis or semi-analytical relationship, Especially for the semi-analytical relationship considering transverse PGD, it has somewhat limited applicability : since it has different formula according to the width of PGD and does not reflect various patterns of PGD which is caused by the decrease of soil stiffness, Therefore, in this study, the applicability of existing analytical relationship is closely investigated through the comparison of FEM results at first. And then, based on meaningful contemplation, improved analytical relationship is proposed. The proposed one models the system behavior of buried pipeline as the combination of cable and beam, and thus it is applicable to arbitrary width of PGD, Moreover, it does reflect various patterns of PGD by introducing interaction pattern coefficient. Through the comparison of numerical results using the FEM and the proposed analytical relationship, rational applicability is objectively verified and noticeable considerations are discussed, Moreover, analyses considering the change of PGD magnitude and patterns are performed.

• Journal of the Earthquake Engineering Society of Korea
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• v.6 no.2
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• pp.51-61
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• 2002

In this research, a numerical algorithm is developed for the response analysis of burined pipelines considering longitudinal permanent ground deformation(PGD) due to liquefaction induced lateral spreading. Buried pipelines and surrounding soil are modeled as continuous pipelines using the beam elements and a series of elasto-plastic springs represented for equivalent soil stiffness, respectively. Idealized various PGD patterns based on the observation of PGD are used as a loading configuration and the length of the lateral spread zone is considered as loading parameter. Numerical results are verified with other research results and efficient applicability of developed procedure is shown. Analyses are performed by varying different parameters such as PGD pattern, pipe diameter and pipe thickness. Through these procedures, relative influences of various parameters on the response of buried pipeline subject to longitudinal PGD are investigated.

• Journal of the Korean Geosynthetics Society
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• v.7 no.3
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• pp.31-40
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• 2008

The deformation behavior of the excavated behind ground due to the displacement shape of retention walls is predicted by numerical analysis, which can be performed using the artificial displacement method with elasto-plastic constitutive model. The displacement shape of the behind ground around the retention wall is similar to the displacement shape of the retention wall. However, far from the retention wall, it changes to the displacement shape of cantilever. The deformation (the settlement, the lateral movement) of the excavated behind ground can be decreased by restraining the upper displacement of the retention wall. The displacement shape of the retention wall due to excavation affects on the plastic failure zone and decreasing zone of stability of the excavated behind ground.

• Journal of the Korean GEO-environmental Society
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• v.11 no.9
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• pp.27-38
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• 2010

A series of model test as well as numerical analysis by FEM was performed to investigate lateral earth pressure acting on a buried pipe in soft ground undergoing horizontal soil movement. A model test apparatus was manufactured so as to simulate horizontal soil movement in model soft ground, in which a model rigid buried pipe was installed. The velocity of soil deformation could be controlled as wanted during testing. The model test was performed on buried pipes with various diameters and shapes to investigate major factors affected the lateral earth pressure. The result of model tests showed that the larger lateral earth pressure acted on the buried pipes under the faster velocity of soil movement. The result of numerical analysis, which was performed under immediate loading condition, showed a similar behavior with the result of model tests under 0.3mm/min to 1.0mm/min velocity of soil deformation. Most of model tests showed the soil deformation-lateral load behavior, in which the first yielding load developed at small soil deformation and elastic behavior was observed by the yielding load. Then, lateral load was kept constant by the second yielding load, in which plastic behavior was observed between the first yielding load and the second yielding one. Beyond the second yielding load, the compression behavior zone was observed. When the velocity was too fast, however, the lateral load was increased with soil deformation beyond the first yielding load without showing the second yielding load. The buried pipes with the larger diameter was subjected to the larger lateral load and the larger increasing rate of lateral load. At small soil deformation, the influence of diameter and shape of buried pipes on lateral load was small. However, when soil deformation was increased considerably, the influence became more and more.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.3
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• pp.107-115
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• 2000

충적지반에 건설된 원형 단면을 갖는 터널은 지진시에 지반의 전단 변형의 영향을 받아 좌우교차로 경사진 타원형상의 변형을 반복한다. 본 논문에서는 이 특별한 진동모드를 이용하여 지반-터널계의 상호작용 및 면진 효과가 검토되었다. 지반과 터널의 경계가 완전히 결합되어 있는 경우에 대한 지반 -터널계의 상호작용 효과 및 지하 구조물의 지진피해를 줄이는 한가지 방법으로써 터널 주위를 면진재로 피복하는 방법에 대한 면진효과가 토론되었다. 그 결과 면진재의 포아송비를 작게 하거나 지반과 면진재의 전단탄성계수의 비를 증가시킴으로서 면진 효가가 증가함을 알 수 있었다.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.55-65
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• 2002

Model tests were performed to investigate the mechanism of lateral earth pressure on a buried pipe, which was installed in a plastic flowing soil mass undergoing lateral movement. On the basis of failure mode tests, the equation of lateral earth pressure to apply Maxwell's visco-elastic model was proposed to consider the soil deformation velocity. Through a series of model tests of differential soil deformation velocity, lateral earth pressure of theoretical equation was compared with experimental results. When lateral soil movement was raised, the lateral earth pressure acting on buried pipe increases linearly with the soil deformation velocity. It shows that the lateral earth pressure on buried pipe is largely affected by soil deformation velocity. When plastic soil movement was raised, lateral earth pressure predicted by theoretical equation showed good agreement with experimental results. Also, coefficient of viscosity by theoretical equation had a good agreement with direct shear test results.

• Tunnel and Underground Space
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• v.11 no.4
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• pp.339-343
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• 2001

Shield tunnel having circular section located in the soil or soft rock layer is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately during earthquakes. Based on this knowledge, the ground-tunnel interaction effect for this particular vibration mode is investigated. The ground surrounding a tunnel is assumed to be a homogeneous elastic medium. The bonded boundary condition on the ground-tunnel interface is considered. This suggests a firm bond between the ground and the tunnel lining. As Poisson's ratio and stiffness of the ground increases, the strain induced within the tunnel lining increases.

• Journal of the Korean GEO-environmental Society
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• v.18 no.3
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• pp.25-30
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• 2017

This paper introduces a novel method to quantify the morphological evolution of the strain response envelope. The strain response envelope is defined as an image in strain increment space corresponding to the unit stress input in stress space. Based on the shape of strain response envelopes, the deformation characteristics of soils can be described using the framework of elastic-plastic theory. Fourier descriptor analysis was used to investigate the morphological characteristics of strain response envelopes. The numerical results show that when the stress input remains in the initial yield surface the Fourier descriptors remain constant. Once the stress input crosses the initial yield surface, every descriptors deals in this study change. Numerical and experimental results of this study show that clear yielding response is only found in natural block samples. Among the Fourier descriptors, the descriptor called as asymmetry is the best for detecting the yield and is minimally sensitive to the number of input stress paths.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.23-36
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• 2008

This study describes model tests on instrumented rectangular-shaped passive row piles embedded in horizontal sand-ground undergoing lateral soil movement. We tried to find the property of row piles dependent on the shape of pile, including the position of the pile in row, pile spacing, and soil movement. The results of test are as follows. The lateral earth pressure diagram variously appeared to be triangle, trapezoid and rectangular by shape and position of pile. The outer pile has a larger bending moment than the inner pile in the case of B-type, the inner piles has larger one than outer pile in case of H-type. $R_f$ (the ratio of resistance to lateral soil movement) was found to increase with increasing pile spacing irrespective of pile-shape. Y/L (location of action of lateral resistance force) for $d_s$ (displacement of soil) and $S_h$ (spacing of pile) appeared to be nearly regular position, and H-type is higher than B-type.

• Journal of the Korean Geotechnical Society
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• v.17 no.4
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• pp.7-14
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• 2001

구조물 하중에 의한 점성토 지반의 침하량을 보다 정확하게 평가하기 위해서는 지반 내의 흙요소가 경험하는 실제적인 응력경로와 이에 따른 변형양상이 적절하게 고려되어야만 한다. 따라서 본 연구에서는 축대칭 조건의 다양한 응력경로를 따라 발생하는 정규압밀 점성토의 변형 거동을 고찰한 기존의 실험적 연구결과를 바탕으로 응력경로법에 근거한 보다 간편하고 합리적인 침하량 평가기법을 제시하였다. 또한 본 연구에서는 제시된 평가기법을 기존의 1차원적인 침하량 평가기법들과 함께 실제와 유사한 조건을 가지는 가상지반의 침하량 산정에 적용해 보았으며, 동일한 조건에 대해 소성모델(MCC 모델)과 혼합압밀이론에 바탕을 둔 유한요소해석을 실시하였다. 그리고 이를 통해 얻어진 결과들을 비교.분석함으로써 기존 평가기법들의 문제점과 한계를 명확히 제시하였으며, 응력증분 평가방법이 침하량 평가에 미치는 영향을 분석하였다.