• Geotechnical Engineering
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• v.10 no.2
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• pp.25-40
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• 1994

In order to investigate behavior of lateral flow by plasticity of soils and construction control due to it, in the case of unsymmetrical surcharge load on the soft soils, we examine the existing theoretical background, and compared and analysed the experimental results by model test. After model test fabricated by model test apparatus, which made full remolding samples of soft soils, we observed the state of behavior for deformation with increasing load step to constant time interval. The critical surcharge and ultimate capacity showed tendency to approach to the proposed value of Jaky and Meyerhof, and the lateral flow pressure of which the maximum value was acted on the depth calculated by z/H=0.26+1.71cu and one third value of the maximum lateral flow pressure acted on the ground surface, approach the trapezoid distribution And maximum lateral flow pressure will be calculated by proposed equation of Hong or simple equation which($\alpha=0.4$) the flow pressure coefficient . of proposed equation by Tschebotarioff exchanged to($\alpha=K_0$) . Basides, the failure surcharge by [(q/$y_m$)-q] and [$S_y-(y_m/S_y)$] showed the smaller than ultimate bearing capacity, especially failure criteria line of control diagram of [$S_y(y_m/S_y)$] will be calculated by following equation. $S_y.=3.15exp[-0.58(y_m/S_y)$

• Journal of the Korean Geotechnical Society
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• v.24 no.1
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• pp.111-118
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• 2008

In the study a 2 dimensional model test was executed to grasp the effect of the taking load of equipments on the ground when improving a soft ground like dredging reclaimed ground. The static load and the dynamic load in the consolidated model ground was $0.02kg/cm^2,\;0.03kg/cm^2\;and\;0.04kg/cm^2$ respectively. After consolidating far two months by consolidation load of $0.02kg/cm^2,\;0.03kg/cm^2\;and\;0.04kg/cm^2$ respectively, the ultimate bearing capacity was $0.16kg/cm^2,\;0.19kg/cm^2,\;0.24kg/cm^2$ respectively. And the energy price of dynamic load test at the same point as the settlement of static load test indicated $E=336{\sim}945kg{\cdot}cm,\;E=252{\sim}780kg{\cdot}cm\;and\;E=323{\sim}727kg{\cdot}cm$ for each consolidation load. When the static load and the dynamic load operated at the same ground condition, the heaving quantity was bigger in the case of the dynamic load than in the case of the static load, and the horizontal displacement quantity the in the case of dynamic load was exhibited very deficiently compared to the quantity in the case of static load test.

• Journal of the Korean Geotechnical Society
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• v.26 no.3
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• pp.35-45
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• 2010

The mechanism of load transfer by punching shear in pile-supported embankments is investigated. Based on the geometric configuration of the punching shear observed in sand fills on soft ground, a theoretical analysis is carried out to predict the embankment loads transferred on a cap beam according to punching shear developed in pile-supported embankments. The equation presented by the theoretical analysis was able to consider the effect of various factors affecting the vertical loads transferred on the cap beam. The reliability of the presented theoretical equation is investigated by comparing it with the results of a series of model tests. The model tests were performed on cap beams, which had two types of width; one is narrow width and the other is wide width. Sand filling was performed through seven steps. Two types of loading pattern were applied at each filling step; one is the long-term loading, in which sand fills at each filling step were kept for 24 hours, the other is the short-term loading, in which sand fills at each filling step were kept for 2 hours. The vertical loads measured in all model tests show good agreement with the ones predicted by the theoretical equation. Finally, the predicted vertical loads also show good agreement with the vertical loads measured in a well-instrumented pile-supported embankment in field, where cap beams were placed on too wide space.

• Magazine of the Korea Concrete Institute
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• v.10 no.2
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• pp.167-178
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• 1998

횡방향철근에 의하여 적절히 구속된 콘크리트 기둥은 강도증가 및 연성의 확보면에서 유리하다. 본 연구의 목적은 횡방향철근에 의하여 구속된 코아콘크리트의 크기,횡방향철근의 간격비 및 체적철근비 등의 변화에 따른 콘크리트 기둥의 극한강도를 포함한 최대하중 이전의 거동 및 최대하중 이후의 거동을 실험적, 해석적으로 고찰함으로써 콘크리트 기둥의 구속효과정도를 규명하려는데 있다. 본 연구에서는 횡구속된 콘크리트 기둥모형의 압축재하실험을 수행하였으며, 최대하중 이전의 거동에 대하여 연속체적 파괴와 소성을 고려한 3차원 모델링을 통한유한요소해석을 실시하였다. 또한 횡구속된 콘크리트 기둥의 변형률국소화 모델에 의한 파괴해석을 통하여 구속된 콘크리트 기둥의 최대하중 이후의 거동을 재현하였다. 해석결과는 압축재하실험의 결과와 비교, 분석되었으며, 이에 따른 구속효과를 규명하였다.

• Journal of the KSME
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• v.18 no.3
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• pp.57-61
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• 1978

안전벨브설비의 기계적설계와 해석에관련된 가장 중요한 고려사항중의 하나는 설비내의 임계점을 찾아내고 그 점에서의 모우멘트를 계산하는 것이다. 만약 굽힘모우멘트를 적절히 계산하지 않으 연 기술기순에 포함된 하중 및 응력기준에 합격할 수 없을 것이다. 이 모우멘트를 결정하는데 최 소한도 본 부록의 2부에 설명된 다음 하중들을 포함함이 바람직하다. 1. 열팽창 2. 사하중 3. 지진 4. 벨브 송출로부터의 반작용력 5. 기타 기계적하중 안전밸브설비의 핵석에서 교차점, 엘보우, 변이점등을 포함한 모든 중요단면 및 기타 관련된 배 관, 용기및 배관설비와 상호작용하는 그들의 지지점들을 포함함이 바람직하다. 안전밸브설비와 그 에 관련된 배관을 직선 또는 곡선 요소들을 연결된 하나의 통합된 질량계로서 모형화하는 것이 가장 적절하다.

• Journal of the Earthquake Engineering Society of Korea
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• v.4 no.2
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• pp.73-82
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• 2000

본연구의 목적은 반복하중을 받는 철근콘크리트 교량 교각의 비선형 이력거동을 해석적으로 예측하는 것이다 이를 위해서 반복적인 횡하중이 작용하는 경우에 실험결과와 일치하는 교각의 하중-변위 이력곡선을 도출하고자 수정된 trilinar 이력거동모델을 이용하였다 철근과 콘크리트의 비선형 거동특성과 각 하중단계에 따른 교각의 중립축을 구하여 소성힌지부의 모멘트와 변형률을 구하고 반복하중하에서의 강성의 변화를 해석적으로 모형화하기 위하여 각기 다른 강성을 갖는 5가지 지선을 갖춘 형태의 이력거동모델식을 제안하였다 본 연구에서는 실험적으로 구한 하중-변위 이력곡선을 이용하여 축하중비 주철근비 및 구속철근비에 따른 강도감소지수와 강성감소지수의 영향을 회귀분석을 이용하여 일반식으로 제안하였다 새로운 이력거동 해석 모델을 프로그램 SARCF III에 적용함으로써 기존 철근콘크리트 교각에 강도 및 강성감소 현상을 정확하게 예측하였다

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.3
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• pp.640-655
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• 2018

Recently, the construction of the urban area has been rapidly increasing, and the excavation work of the ground has been frequently performed at the upper part of the existing underground structures. Especially, when the structure is constructed after the excavation of the ground, the loading and unloading process in the ground under the excavation basement can affect the existing underground structures. Therefore, in order to maintain the stability of the existing underground structure due to the excavation of the ground, it is necessary to accurately grasp the influence of the excavation and the structure load in the adjoining part. In this study, the effect of the excavation of the ground and the new structure load on the existing tunnel was experimentally implemented and the influence of the adjacent construction on the existing tunnel was investigated. For this purpose a large testing model with 1/5 scale of the actual size was manufactured. The influence of ground excavation, width of the load due to new structure, and distance between centers of tunnel and of excavation on the existing tunnel was investigated. In this study, it was confirmed that the influence on the existing tunnel gets larger, as the excavation depth get deeper. At the same distance, it was confirmed that the tunnel displacement increased up to three times according to the increase of the building load width. That is, the load width influences the existing tunnel larger than the excavation depth. As the impact of the distance between centers of tunnel and of excavation, it was confirmed that tunnel crown displacement decreased by 48%. The result showed that a tunnel is located in the range of 1D (D: tunnel diameter) from the center of excavation, the effect of excavation is the largest.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.499-509
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• 2016

In recent years, the use of underground spaces becomes more frequent and the demands for urban tunnels are rapidly increasing. The urban tunnels constructed in the ground with a shallow and soft cover might be deformed in various forms on the face, which would lead, the tunnels to behavior 3-dimensionally, which may have a great impact on the longitudinal load transfer. The tunnel face might deform in various forms depending on the construction method, overburden and the heterogeneity of the ground. And accordingly, the type and size of the distribution of the load transferred to the ground adjacent to the tunnel face as well as the form of the loosened ground may appear in various ways depending on the deformation form of the tunnel face. Therefore, in this study was conducted model tests by idealizing the deformation behavior of the tunnel face, that were constant deformation, the maximum deformation on the top and the maximum deformation on the bottom. And the test results were analyzed focusing on the deformation of the face and the longitudinal load transfer at the ground above the tunnel. As results, it turned out that the size and the distribution type of the load, which was transferred to the tunnel as well as the earth pressure on the face were affected by the deformation type of the face. The largest load was transferred to the tunnel when the deformation was in a constant form. Less load was transferred when the maximum deformation on the bottom, and the least load was transferred when the maximum deformation on the top. In addition, it turned out that, if the cover became more shallow, a longitudinal load transfer in the tunnel would limited to the region close to the face; however, if the cover became higher than a certain value, the area of the load transfer would become wider.

• Journal of the Korean Geotechnical Society
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• v.40 no.4
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• pp.33-47
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• 2024

Offshore wind structures are subject to long-term repeated horizontal loads from wind, waves, and currents, making it essential to consider these loads in the design of offshore foundations. In this respect, monopiles are large-diameter hollow steel pipes that are relatively simple to construct compared with piles used on onshore sites. They can provide stable support for wind structures and have well-established design codes, leading to their widespread use globally. The behavior of monopiles under lateral static loads is typically assessed using the p-y method proposed by the American Petroleum Institute (API). However, the applicability of p-y curves to large-diameter monopiles exposed to repeated cyclic horizontal loads, such as those experienced in offshore wind applications, must yet be evaluated. Thus, this study evaluated the behavior of monopiles under two-way cyclic horizontal loads in loose silty sand, a representative soil type of the southwestern coast of Korea, using centrifuge model tests. The results demostrated that the behavior of monopiles varied depending on the loading level, number of cycles, and direction of the cyclic loads. Furthermore, the p-y curve method proposed by the API overestimated the behavior of a large-diameter monopile installed in silty sand under two-way cyclic loads.

• Journal of the Korean Geotechnical Society
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• v.24 no.6
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• pp.85-93
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• 2008

For long piles driven in deep clay deposits, it is difficult to estimate the ultimate bearing capacity due to large resistance induced by long embedded depth, and also the load transfer curve due to large residual load induced by negative skin friction, even with the performance of pile load tests. In this research, a hi-directional load test on a PHC pile driven in deep soft deposit was performed in order to evaluate the tip and shaft resistances separately, which are feasible to estimate the ultimate bearing capacity of the pile. Residual load of the pile was determined by continuous monitoring of pile strains after the pile installation. The true resistance and true load-movement curve of the pile were properly estimated by taking account of the residual load. A model far behavior of the shaft resistance vs. movement was also proposed, which includes the effects of residual load based on the experiment. Consequently, it was proved that the residual load should be taken into consideration for correctly analyzing load test results of piles in deep clay deposits.