• 한국지진공학회논문집
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• 제13권3호
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• pp.21-28
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• 2009

지반-말뚝-구조의 상호작용을 정밀하게 해석하기 위해서는 토층, 말뚝 그리고 구조물의 적절한 묘사가 필요하다. 일반적으로 사용하는 유한요소해석의 경우에는 지반이나 구조물의 물성이 바뀌는 경계를 따라서 요소의 경계가 정해지게 된다. 그러나 실제로는 토층 단면과 말뚝의 형상이 매우 복잡하여 요소의 배열이 매우 어려운 작업이 될 수 있다. 이 어려움을 해결하기 위하여, 이 논문에서는 불연속선의 위치에 관계없이 규칙적인 요소를 사용하여 쉽게 적분을 가능하게 하는 다른 적분 방법을 채택하였다. 이 방법을 적용함으로 써 요소는 매우 빠르고 규칙적인 강성 매트릭스를 만든다. 구조물 응답에 대한 토층과 말뚝의 영향을 조사하였고, 예를 통하여 본 방법의 유효성을 보였다. 탄성 말뚝의 사용으로 20% 대의 가속도 감소 효과를 얻었고 지반 층의 모양에 따라 그 영향이 변하는 것을 확인하였다.

• Earthquakes and Structures
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• 제11권1호
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• pp.141-163
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• 2016

Fiber models have been developed and applied to various structural elements such as shear walls, beams and columns. Only scarcely have fiber models been applied to circular foundation systems such as cast in drilled holes shafts (CIDH). In pile foundations with constraint head boundary conditions, shear deformations can easily contribute to the lateral pile response. However, soil structure interaction formulations such as the p-y method, commonly used for lateral pile design, do not include structural shear deformations in its traditional derivation method. A fiber model that couples shear and axial-bending behavior, originally developed for wall elements was modified and validated on circular cross sections (columns) before being applied to a 0.61 m diameter reinforced concrete (RC) pile with fixed head boundary conditions. The analytical response was compared to measured test results of a fixed head test pile to investigate the possible impact of pile shear deformations on the displacement, shear, and moment profiles of the pile. Results showed that shear displacements and forces are not negligible and suggest that nonlinear shear deformations for RC piles should be considered for fixed-head or similar conditions. Appropriate sensor layout is recommended to capture shear deformation when deriving p-y curves from field measurements.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 봄 학술발표회 논문집
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• pp.151-158
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• 2000

The lateral deformation of one row pile groups was investigated based on analytical study and a numerical analysis. The emphasis was on quantifing the load transfer of pile groups subjected to lateral soil movement. An analytical method to consider pile-soil interaction in weathered soil was developed using load-transfer curve methods. Through the comparative study, it is found that the prediction by present approach is in good agreement with the general trend observed by in-situ measurements.

• Geomechanics and Engineering
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• 제34권5호
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• pp.529-545
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• 2023

The coupled soil-pile-structure seismic response is recently in the spotlight of researchers because of its extensive applications in the different fields of engineering such as bridges, offshore platforms, wind turbines, and buildings. In this paper, a simple analytical model is developed to evaluate the dynamic performance of seismically isolated bridges considering triple interactions of soil, piles, and bridges simultaneously. Novel expressions are proposed to present the dynamic behavior of pile groups in inhomogeneous soils with various shear modulus along with depth. Both cohesive and cohesionless soil deposits can be simulated by this analytical model with a generalized function of varied shear modulus along the soil depth belonging to an inhomogeneous stratum. The methodology is discussed in detail and validated by rigorous dynamic solution of 3D continuum modeling, and time history analysis of centrifuge tests. The proposed analytical model accuracy is guaranteed by the acceptable agreement between the experimental/numerical and analytical results. A comparison of the proposed linear model results with nonlinear centrifuge tests showed that during moderate (frequent) earthquakes the relative differences in responses of the superstructure and the pile cap can be ignored. However, during strong excitations, the response calculated in the linear time history analysis is always lower than the real conditions with the nonlinear behavior of the soil-pile-bridge system. The current simple and efficient method provides the accuracy and the least computational costs in comparison to the full three-dimensional analyses.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2002년도 춘계 학술발표회 논문집
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• pp.125-132
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• 2002

In this study, a numerical method is developed for nonlinear analysis for soil-pile-structure interaction system in time domain. Finite elements considering material nonlinearity are used for the near field and boundary elements for the far field. In the near field, frame elements are used for modeling a pile and plane-strain elements for surrounding soil and superstructure. In. the far field, boundary element formulation using the dynamic fundamental solution is adopted and coupled with the near field. Transformation of stiffness matrices of boundary elements into time domain is performed by inverse FFT. Stiffness matrices in the near field and far field are coupled. Newmark direct time integration method is applied. Developed soil-pile-structure interaction analysis method is verified with available literature and commercial code. Also, parametric studies by developed numerical method are performed. And seismic response analysis is performed using actual earthquake records.

• 한국철도학회논문집
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• 제6권1호
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• pp.29-40
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• 2003

In this study, the three dimensional pile-soil dynamic interaction analysis of the railway bridge pile foundation was performed using SASSI 2000 program and the applicability of SASSI 2000 about an evaluation of the seismic stability of a pile foundation was examined. The numerical analysis was executed on the two site of actual construction and input properties such as the acceleration of bedrock were estimated by one dimensional seismic response analysis using the Pro-SHAKE. Consequently, all the piles of the subject of investigation showed that displacement occurred within a permitted limit and the shear force and moment largely occurred at the point where the soil stiffness varied rapidly.

• 한국지반공학회논문집
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• 제18권1호
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• pp.127-132
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• 2002

사질토 지반에 근입된 모형말뚝에 대한 진동대 실험을 수행하여 말뚝지반 동적 상호작용 현상을 분석하고 동적군말뚝 효과를 산정하였다. 실험은 단말뚝과 말뚝간격을 말뚝직경의 3~8배로 변화시킨 $3\times3$ 군말뚝에 대하여 수행하였다. 동적 군맡뚝 효과는 단말뚝과 군말뚝의 동적 p-y곡선의 중심 기울기를 비교하여 산정하였고, 실험에서 얻어진 p-y곡선은 API의 반복 p-y곡선과 비교하였다. 실험결과 말뚝 간격, 입력 지진파의 주파수와 진폭 변화에 따른 동적 군말뚝 효과를 산정할 수 있었다.

• 한국지반환경공학회 논문집
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• 제12권1호
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• pp.41-50
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• 2011

본 연구에서는 단독말뚝의 측면에서 시공되는 터널에 의한 말뚝의 거동에 대하여 3차원 수치해석을 통하여 분석하였다. 수치해석을 통하여 터널-말뚝-지반의 상호거동에 대한 심도 있는 분석을 실시하였다. 수치해석을 통해 말뚝의 침하, 말뚝과 주변지반 사이의 상대변위, 전단응력 및 말뚝의 축력변화를 고찰하였다. 특히 터널굴착에 의한 전단응력의 전이과정에 대한 심도 있는 분석을 실시하였다. 터널굴착에 의한 말뚝과 인근지반에서의 상대변위 변화로 인하여 말뚝에 작용하는 전단응력 및 축력의 분포가 변하게 되는 것으로 나타났다. 터널 중심부의 상부에서는 하향의 전단응력이 발생하는 반면(Z/L=0.0-0.7~0.8), 그 하부에서는 (Z/L=0.7~0.8-1.0) 상향의 전단응력이 발생하여 말뚝에 압축력이 발생된다, 이때 Z는 임의의 심도, L은 말뚝의 길이다. 터널굴착이 종료된 후 말뚝에는 최대 $0.475P_a$의 압축력이 발생하였다, 이때 $P_a$는 말뚝의 설계지지력이다. 수치해석을 통해서 도출된 터널굴착이 말뚝 거동에 미치는 영향에 대해 상세히 고찰하였다.

• Geomechanics and Engineering
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• 제11권4호
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• pp.553-570
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• 2016

A series of three-dimensional (3D) parametric finite element analyses have been performed to study the influence of the relative locations of pile tips with regards to the tunnel position on the behaviour of single piles and pile groups to adjacent tunnelling in weathered soil. When the pile tips are inside the influence zone, which considers the relative pile tip location with respect to the tunnel position, tunnelling-induced pile head settlements are larger than those computed from the Greenfield condition. However, when the pile tips are outside the influence zone, a reverse trend is obtained. When the pile tips are inside the influence zone, the tunnelling-induced tensile pile forces mobilised, but when the pile tips are outside the influence zone, compressive pile forces are induced because of tunnelling, depending on the shear stress transfer mechanism at the pile-soil interface. For piles connected to a cap, tensile and compressive forces are mobilised at the top of the centre and side piles, respectively. It has been shown that the increases in the tunnelling-induced pile head settlements have resulted in reductions of the apparent factor of safety up to approximately 43% when the pile tips are inside the influence zone, therefore severely affecting the serviceability of the piles. The pile behaviour, when considering the location of the pile tips with regards to the tunnel, has been analysed in great detail by taking the tunnelling-induced pile head settlements, axial pile forces, apparent factor of safety of the piles and shear transfer mechanism into account.

• 한국지반환경공학회 논문집
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• 제20권10호
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• pp.39-46
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• 2019

상부구조물을 지지하는 무리말뚝의 내진설계 시 지반-구조물의 상호작용이 고려되어야 한다. 무리말뚝 설계 시 지반과 구조물의 비선형 관계는 p-y 곡선이 많이 사용되고 있으며 지진과 같은 동적하중조건에서 지반-구조물의 상호작용이 고려된 동적 p-y 곡선을 무리말뚝의 내진설계에 사용하기 위한 연구가 진행되고 있다. 그러나 이와 같은 연구는 말뚝 캡에 의한 지지효과 및 상부구조물의 관성거동에 의한 상호작용은 고려되지 않았다. 이에 본 연구에서는 사질토 지반에 근입된 상부구조물을 지지하는 무리말뚝에서 말뚝 캡의 변화가 무리말뚝에 미치는 영향을 확인하기 위해 말뚝의 배열 및 중심 간격은 고정하고 말뚝 캡 측면과 말뚝 중심 간격을 변화시켜 진동대 모형실험을 수행하였다. 그 결과 무리말뚝에서 말뚝 캡 측면과 말뚝 중심 간격의 변화가 말뚝의 동적 p-y 곡선 및 무리말뚝 효과에 영향을 미치는 것으로 나타났다.