• 한국농공학회지
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• 제34권2호
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• pp.60-72
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• 1992

This study aims at predicting the behavior of saturated soft clayey foundation subjected to earth structure loads such as tidal dike, embankment etc. by using Biot's consolidation equation coupled with elasto-viscoplastic constitutive model. To validate the computer program developed b author, a case study was performed for the site of Kwang-yang steel works improved by sand drain, where since the beginning of the works, field measurements(settlement, lateral displacement and excess pore water pressure) had been accurately achieved. Comparisons between numerical results and observation values were carried out. The main results obtained are summarized as follows : 1. Settlement and lateral displacement between numerical and observation values show satisfactory accordance. 2. As for the exess pre water pressure, numerical results appear to be larger than observation values, which may be due to the existence of sand seams which were not found during soil investigation. 3. Useful data available for failure prediction of soft foundation can be secured by examining lateral displacement, settlement, exess pore water pressure and stress paths.

• 한국조경학회:학술대회논문집
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• 한국조경학회 2007년도 Journal of Landscape Architecture in Asia Vol.3
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• pp.66-71
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• 2007

The settlement era($1845{\sim}1943$) in Shanghai was divided as periods parting point by the establishment of habitats, the establishment of the International Settlement and its two times expansions, the establishment of the French Settlement and its three times expansions. Investigations on the formation process and its characteristics of two settlement parks during each period were carried out. The formation process of Shanghai settlement park was divided simply into the settlement park foundation time correspond to the settlement expansion time(the International Settlement was from 1845 to 1898, the French Settlement was from 1849 to 1913) and the settlement park development time after the settlement expansion(the International Settlement is from 1899 to 1943, the French Settlement is from 1914 to 1943) by the characteristics such as its forming time, quantity and distribution.

• International Journal of Naval Architecture and Ocean Engineering
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• 제9권4호
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• pp.418-428
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• 2017

In offshore area, newly deposited Quaternary loose seabed soils are widely distributed. There are a great number of offshore structures has been built on them in the past, or will be built on them in the future due to the fact that there would be no very dense seabed soil foundation could be chosen at planed sites sometimes. However, loosely deposited seabed foundation would bring great risk to the service ability of offshore structures after construction. Currently, the understanding on wave-induced liquefaction mechanism in loose seabed foundation has been greatly improved; however, the recognition on the consolidation characteristics and settlement estimation of loose seabed foundation under offshore structures is still limited. In this study, taking a semi-coupled numerical model FSSI-CAS 2D as the tool, the consolidation and settlement of loosely deposited sandy seabed foundation under an offshore breakwater is investigated. The advanced soil constitutive model Pastor-Zienkiewics Mark III (PZIII) is used to describe the quasi-static behavior of loose sandy seabed soil. The computational results show that PZIII model is capable of being used for settlement estimation problem of loosely deposited sandy seabed foundation. For loose sandy seabed foundation, elastic deformation is the dominant component in consolidation process. It is suggested that general elastic model is acceptable for subsidence estimation of offshore structures on loose seabed foundation; however, Young's modulus E must be dependent on the confining effective stress, rather than a constant in computation.

• 한국지반신소재학회논문집
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• 제5권1호
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• pp.9-14
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• 2006

국내에서는 여러 가지 형상 및 친환경적인 보강토옹벽 구조물의 시공은 최근 많이 확대되고 있다. 전체구조물의 안정과 더불어 블록에 발생되는 균열은 대부분 원인으로 기초의 침하에 의한 경우가 많다. 본 연구에서는 기초지반의 부등침하와 관련하여 기초지지력의 설계시 평가법 및 시공시 평가법에 대하여 고찰하였다. 현장에서 실시되고 있는 실제 시공사례를 이용하여 보강토옹벽의 안정을 기초지지력을 만족하지 못하는 경우에 대한 대책방안을 제시하고 그 방안의 활용성을 제시하였다. 보강토옹벽의 기초부분은 전체사면의 잠재적 활동면의 범주내에 있게 되므로 기초지지력을 담당하는 지반은 지반의 활동저항력에 영향을 받게 된다. 따라서, 기초지지력을 부담하는 기초지반은 지지력에 대한 안정을 만족할 뿐 만 아니라 전체사면활동에 저항하는 억지능력에 대하여도 고려되어야 한다.

• Steel and Composite Structures
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• 제52권2호
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• pp.135-143
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• 2024

Once the foundation displacement of the transmission tower occurs, additional stress will be generated on the tower members, which will affect the seismic response of transmission tower-line systems (TTLSs). Furthermore, existing research has shown that the reciprocating slippage of joints needs to be considered in the seismic analysis. The hysteretic behavior of joints is obtained by model tests or numerical simulations, which leads to the low modeling efficiency of TTLSs. Therefore, this paper first utilized numerical simulation and model tests to construct a BP neural network for predicting the skeleton curve of joints, and then a numerical model for a TTLS considering the bolt slippage was established. Then, the seismic response of the TTLS under foundation displacement was studied, and the member stress changes and the failed member distribution of the tower were analyzed. The influence of foundation displacement on the seismic performance were discussed. The results showed that the trained BP neural network could accurately predict the hysteresis performance of joints. The slippage could offset part of the additional stress caused by foundation settlement and reduce the stress of some members when the TTLS with foundation settlement was under earthquakes. The failure members were mainly distributed at the diagonal members of the tower leg adjacent to the foundation settlement and that of the tower body. To accurately analyze the seismic performance of TTLSs, the influence of foundation displacement and the joint effect should be considered, and the BP neural network can be used to improve modeling efficiency.

• Geomechanics and Engineering
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• 제20권2호
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• pp.87-101
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• 2020

The construction of combined pile-raft foundations is considered as the main option in designing foundations in high-rise buildings, especially in soils close to the ground surface which do not have sufficient bearing capacity to withstand building loads. This paper deals with the geotechnical report of the Northern Fereshteh area of Tabriz, Iran, and compares the characteristics of the single pile foundation with the two foundations of pile group and geogrid. Besides, we investigate the effects of five principal parameters including pile diameter and length, the number of geogrid layers, the depth of groundwater level, and pore water pressure on vertical consolidation settlement and pore water pressure changes over a year. This study assessed the mechanism of the failure of the soil under the foundation using numerical analysis as well. Numerical analysis was performed using the two-dimensional finite element PLAXIS software. The results of fifty-four models indicate that the diameter of the pile tip, either as a pile group or as a single pile, did not have a significant effect on the reduction of the consolidation settlement in the soil in the Northern Fereshteh Street region. The optimum length for the pile in the Northern Fereshteh area is 12 meters, which is economically feasible. In addition, the construction of four-layered ten-meter-long geogrids at intervals of 1 meter beneath the deep foundation had a significant preventive impact on the consolidation settlement in clayey soils.

• Geomechanics and Engineering
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• 제5권4호
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• pp.363-377
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• 2013

Any structure constructed on the earth is supported by the underlying soil. Foundation is an interfacing element between superstructure and the underlying soil that transmits the loads supported by the foundation including its self weight. Foundation design requires evaluation of safe bearing capacity along with both immediate and long term settlements. Weak and compressible soils are subjected to problems related to bearing capacity and settlement. The conventional method of design of footing requires sufficient safety against failure and the settlement must be kept within the allowable limit. These requirements are dependent on the bearing capacity of soil. Thus, the estimation of load carrying capacity of footing is the most important step in the design of foundation. A number of theoretical approaches, in-situ tests and laboratory model tests are available to find out the bearing capacity of footings. The reliability of any theory can be demonstrated by comparing it with the experimental results. Results from laboratory model tests on square footings resting on sand are presented in this paper. The variation of bearing capacity of sand below a model plate footing of square shape with variation in size, depth and the effect of permissible settlement are evaluated. A steel tank of size $900mm{\times}1200mm{\times}1000mm$ is used for conducting model tests. Bearing capacity factor $N_{\gamma}$ is evaluated and is compared with Terzaghi, Meyerhof, Hansen and Vesic's $N_{\gamma}$ values. From the experimental investigations it is found that, as the depth of sand cushion below the footing ($D_{sc}$) increases, ultimate bearing capacity and settlement values show an increasing trend up to a certain depth of sand cushion.

• 한국지반공학회논문집
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• 제20권1호
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• pp.131-139
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• 2004

지내력기초 설계와 시공을 위해 실시하는 평판재하시험 결과로부터 실제 기초지반의 지지력 및 침하량을 산정할때 scale effect를 고려해야 하는데 국내에는 scale effect 적용기준이나 관련 시험자료가 없다. 그래서, 화강풍화토 지반에서 재하판 크기별 지지력 및 침하량의 상관관계를 파악하기 위해 모형토조 및 현장 평판재하시험을 실시하였다. 토조시험은 토조내에 지층을 형성한후 함수비 조건, 다짐횟수, 습윤 단위중량, 및 재하판 직경(D15, 25cm)별로 모형토조$(2,000\times 2,000\times 1,000mm)$에서 실시하였다. 현장 재하시험은 재하판 직경$(D15, 25, 30, 40, 75\times 75, 140\times 210cm)$별로 실시하였다. 재하시험 결과분석과 수치해석을 통해 토사 및 암반지반에서 지내력 기초설계시 Scale effect를 계산하기 위한 지지력 및 침하량 산정식을 제시하였다.

• Geomechanics and Engineering
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• 제13권1호
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• pp.119-139
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• 2017

Static Penetration Test (CPT) and Dynamic Penetration Test (DPT) are commonly used in-situ tests in a routine geotechnical investigation. Besides their use for qualitative investigation (lithology, homogeneity and spatial variability), they are used as practical tools of geotechnical characterization (resistance to the penetration, soil rigidity) and modern foundation design as well. The paper aims at presenting the results of an extensive research work on the evaluation of the 1D primary consolidation settlement of saturated clayey soils on the basis of the CPT or DPT tests. The work is based on an analysis of the correlations between the tip resistance to penetration measured in these tests and the parameters of compressibility measured by the compressibility oedometer test, through a local geotechnical database in the northern Algeria. Such an analysis led to the proposal of two methods of calculation of the settlement, one based on the CPT test and the other one on the DPT. The comparison between the predicted settlements and those computed on the basis of the oedometer test showed a good agreement which demonstrate the possbility to use the CPT and DPT tests as reliable tools of computation of foundation settlements in clayey soils.

• Geomechanics and Engineering
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• 제16권4호
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• pp.449-461
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• 2018

The load sharing ratio (${\alpha}_{pr}$) of piles is one of the most common problems in the preliminary design of piled raft foundations. A series of 3D numerical analysis are conducted so that special attentions are given to load sharing characteristics under varying conditions, such as pile configuration, pile diameter, pile length, raft thickness, and settlement level. Based on the 3D FE analysis, influencing factors on load sharing behavior of piled raft are investigated. As a result, it is shown that the load sharing ratio of piled raft decreases with increasing settlement level. The load sharing ratio is not only highly dependent on the system geometries of the foundation but also on the settlement level. Based on the results of parametric studies, the load sharing ratio is proposed as a function of the various influencing factors. In addition, the parametric analyses suggest that the load sharing ratios to minimize the differential settlement of piled raft are ranging from 15 to 48% for friction pile and from 15 to 54% for end-bearing pile. The recommendations can provide a basis for an optimum design that would be applicable to piled rafts taking into account the load sharing characteristics.