• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.269-276
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• 2000

Granular compaction piled raft systems have been effectively used in soft ground foundation to improve not only settlement but also bearing capacity. In the present study, to examine the behavior characteristics and bulging failure zone on granular compaction piled raft system, carbon rod tests have been performed. The test results are compared with the zone of bulging failure and the effects of pile-pile interaction obtained from the analytical approaches. In addition, parametric studies are peformed with considering pile slenderness ratio, Poisson's ratio and load sharing ratio.

• Geomechanics and Engineering
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• 제10권4호
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• pp.547-563
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• 2016

This paper describes a geotechnical field investigation in Giresun hazelnut licenced warehause and spot exchange during twelve months to determine the soil profile and static project applicability. It is also aimed to determine the superstructure loads and evaluate the relevance of foundation filling materials of the main, laboratory, package and admin buildings. The main building has $88.50{\times}63.20(5593.2)m^2$ site area. It has a big raft foundation. Eleven geotechnical reports were prepared between 2 December 2014 and 25 May 2015. Maximum settlements and safe bearing capacities were calculated to decide to be able to proceed to the next step. Also, the detail observations and evaluations were presented from October 2014 to December 2014. It has been seen that the foundation is designed as a single foundation one. But, in the light of observations, it has been evaluated that the foundation project for package building is not adequate, and after these excavations it must be revised as a raft foundation. The thickness of foundation and structural details should be defined/drawn after analyzing the details by using a special software. Construction joints should be designed between different buildings interfaces to avoid damages and cracks with in different settlements. The environmental drainage must be projected and applied to avoid the probable damage of surface waters on foundations.

• Structural Engineering and Mechanics
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• 제54권5호
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• pp.829-853
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• 2015

This is an experimental study to investigate the behaviour of piled raft system in different types of sandy soil. A small scale "prototype" model was tested in a sand box with load applied to the foundation through a compression jack and measured by means of load cell. The settlement was measured at the raft by means of dial gauges, three strain gauges were attached on piles to measure the strains and calculate the load carried by each pile in the group. Nine configurations of group ($1{\times}2$, $1{\times}3$, $1{\times}4$, $2{\times}2$, $2{\times}3$, $2{\times}4$, $3{\times}3$, $3{\times}4$ and $4{\times}4$) were tested in the laboratory as a free standing pile group (the raft not in contact with the soil) and as a piled raft (the raft in contact with the soil), in addition to tests for raft (unpiled) with different sizes. It is found that when the number of piles within the group is small (less than 4), there is no evident contribution of the raft to the load carrying capacity. The failure load for a piled raft consisting of 9 piles is approximately 100% greater than free standing pile group containing the same number of piles. This difference increases to about 4 times for 16 pile group. The piles work as settlement reducers effectively when the number of piles is greater than 6 than when the number of piles is less than 6. The settlement can be increased by about 8 times in ($1{\times}2$) free standing pile group compared to the piled raft of the same size. The effect of piled raft in reducing the settlement vanishes when the number of piles exceeds 6.

• Wind and Structures
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• 제22권6호
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• pp.617-633
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• 2016

In this paper, the analysis of hyperbolic cooling tower on elastic subsoil exposed to unsymmetrical wind loading is presented. Modified Vlasov foundation model is used to determine the soil parameters as a function of vertical deformation profile within subsoil. The iterative parameter updating procedure involves the use of Open Application Programming Interface (OAPI) feature of SAP2000 to provide two way data flow during execution. A computing tool coded in MATLAB employing OAPI is used to perform the analysis of hyperbolic cooling tower with supporting columns over a hollow annular raft founded on elastic subsoil. The analysis of such complex soil-structure system is investigated under self-weight and unsymmetrical wind load. The response of the cooling tower on elastic subsoil is compared with that of a tower that its supporting raft foundation is treated as fixed at the base. The results show that the effect of subsoil on the behavior of cooling tower is considerable at the top and bottom of the wall as well as supporting columns and raft foundation. The application of a full-size cooling tower has demonstrated that the procedure is simple, fast and can easily be implemented in practice.

• 한국지반공학회논문집
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• 제25권7호
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• pp.23-33
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• 2009

본 연구에서는 말뚝지지 전면기초의 거동을 원심모형시험과 수치해석기법을 이용하여 연구하였다. 단말뚝, 기초판, 군말뚝 및 말뚝지지 전면기초의 극한지지력 비교를 통하여 말뚝지지 전면기초의 지지력을 평가하였고, 말뚝과 기초판에 전달되는 하중 분담율을 분석하여 말뚝지지 전면기초의 극한지지력을 산정할 수 있는 경험적 상관계수를 획득하였다. 또한, 원심모형시험과 동일말뚝조건을 대상으로 수치 시뮬레이션을 수행하여 원심모형시험 결과를 검증하고 말뚝지지 전면기초의 지지력을 위한 상관계수를 평가하였다.

• 대한토목학회논문집
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• 제44권2호
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• pp.191-201
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• 2024

본 연구에서는 3차원 유한요소 해석을 이용하여 기존 건축물의 수직증축 리모델링을 위한 말뚝지지 조건에 따른 기존 및 보강말뚝의 거동에 대해 분석하였다. 수치해석에서 기존 및 보강말뚝 거동의 영향인자로는 캡지지 조건(군말뚝 기초, 말뚝지지 전면기초)과 기존말뚝의 선단근입조건(암반근입, 토사근입)을 고려하였다. 기존말뚝과 보강말뚝의 정량적 거동 분석을 위해 침하량, 하중분담률, 해석 단계에 따른 심도별 축력을 결과로 도출하였다. 분석 결과, 선재하공법 적용에 기인하여 보강말뚝에서 가장 큰 침하량이 발생한 것을 확인하였다. 특히 선단근입조건에 관계없이 군말뚝에서 큰 침하량이 발생하였다. 말뚝지지 전면기초에서는 기초판(Raft)의 영향으로 인해 침하량 및 기존말뚝과 보강말뚝의 하중분담률이 작아지는 것을 확인하였다. 심도별 축력 분포도에서는 군말뚝과 말뚝지지 전면기초 간의 축력 분포에 차이가 나타났으며, 이는 침하량과 하중분담률에 영향을 미치는 주요 요소로 작용하는 것으로 보인다. 수치해석 결과를 바탕으로 수직증축 리모델링을 위한 말뚝기초 설계에 있어서 캡지지 조건과 선단근입 조건을 고려해야 함을 확인하였다.

• 한국지반공학회논문집
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• 제27권4호
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• pp.33-41
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• 2011

서 김해평야에 위치하는 연장 2km의 철도제방은 정규압밀점토인 연약지반 상에 건설되었다. 연직 배수재를 타입하고 단계시공으로 1단계의 시공을 한 직후에 제방은 종방향 균열이 생겨 원호활동의 징조가 나타났다. 이 단계에서 piled raft로 설계변경하고 제방을 완공하였다. 여러 측점에 다양한 계측기를 설치하여 제방 시공 중 piled raft의 거동을 관찰하였다. 이 결과를 정리하여 piled raft 기초의 안전성을 분석한 결과를 이 논문에 기술하였다. 말뚝 무리가 마찰말뚝으로 작용할 때에는 piled raft 기초는 정규압밀점토에서도 안전하고 경제적인 설계가 될 수 있다는 것을 계측결과로 부터 알게 되었다.

• 한국지반공학회논문집
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• 제31권2호
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• pp.13-25
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• 2015

최근 마이크로 파일의 활용 빈도가 점차 증가함에 따라 몇몇 연구자들은 마이크로파일 및 마이크로파일-기초에 대한 관련 연구를 수행하였다. 그러나 대부분의 관련연구는 모래지반을 대상으로 한 경우이다. 또한 마이크로파일-기초시스템의 지지특성은 기초시스템내 하부지반의 파괴거동과 파일설치조건에 따라 기초시스템의 지지력이 달라지나 이를 고려하지 않고 있다. 따라서 본 연구에서는 파괴거동이 상이한 지반에 설치된 마이크로파일-기초시스템의 지지력을 평가위해 수치해석을 수행하였다. 해석결과, 전면전단파괴가 발생한 모래지반에서는 기초시스템의 파일을 양 또는 음의 각도로 설치한 경우가 수직파일로 설치된 기초시스템보다 큰 것으로 나타났다. 관입파괴형상으로 파괴가 발생한 실트지반의 경우, 파일이 교차하도록 음의 각도로 설치한 기초시스템이 수직파일인 경우보다 지지력이 증가하였다. 그리고 양의 각도로 설치한 경우에는 수직인 경우와 유사한 것으로 나타났다.

• Earthquakes and Structures
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• 제14권1호
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• pp.85-94
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• 2018

The paper focuses on the seismic responses of a hyperbolic cooling tower resting on soil foundation represented by the three-parameter Vlasov elastic soil model. The three-parameter soil model eliminates the necessity of field testing to determine soil parameters such as reaction modulus and shear parameter. These parameters are calculated using an iterative procedure depending on the soil surface vertical deformation profile in the model. The soil and tower system are modeled in SAP2000 structural analysis program using a computing tool coded in MATLAB. The tool provides a two-way data transfer between SAP2000 and MATLAB with the help of Open Application Programming Interface (OAPI) feature of SAP2000. The response spectrum analyses of the tower system with circular V-shaped supporting columns and annular raft foundation on elastic soil are conducted thanks to the coded tool. The shell and column forces and displacements are presented for different soil conditions and fixed raft base condition to investigate the effects of soil-structure interaction. Numerical results indicate that the flexibility of soil foundation leads to an increase in displacements but a decrease in shell membrane and column forces. Therefore, it can be stated that the consideration of soil-structure interaction in the seismic response analysis of the cooling tower system provides an economical design process.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.157-171
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• 2009

A 151 storey super high-rise building located in an area of reclaimed land constructed over soft marine clay in Songdo, Korea is currently under design. This paper describes the design process of the foundation system of the supertall tower, which is required to support the large building vertical and lateral loads and to restrain the horizontal displacement due to wind and seismic forces. The behaviour of the foundation system due to these loads and foundation stiffness influence the design of the building super structure, displacement of the tower, as well as the raft foundation design. Therefore, the design takes in account the interactions between soil, foundation and super structure, so as to achieve a safe and efficient building performance. The site lies entirely within an area of reclamation underlain by up to 20m of soft to firm marine silty clay, which overlies residual soil and a profile of weathered rock. The nature of the foundation rock materials are highly complex and are interpreted as possible roof pendant metamorphic rocks, which within about 50m from the surface have been affected by weathering which has reduced their strength. The presence of closely spaced joints, sheared and crushed zones within the rock has resulted in deeper areas of weathering of over 80m present within the building footprint. The foundation design process described includes the initial stages of geotechnical site characterization using the results of investigation boreholes and geotechnical parameter selection, and a series of detailed two- and three-dimensional numerical analysis for the Tower foundation comprising over 172 bored piles of varying length. The effect of the overall foundation stiffness and rotation under wind and seismic load is also discussed since the foundation rotation has a direct impact on the overall displacement of the tower.