• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 1999년도 가을 학술발표회 논문집
• /
• pp.3-44
• /
• 1999

This paper discusses the lateral behavior of single and group piles in homogeneous and non-homogeneous(two layered) soil. In the single pile, the model tests were conducted to investigate the effects on ratio of lower layer height to embedded pile length, ratio of soil modules of upper layer to lower layer, boundary rendition of pile head and tip, embedded pile length, pile construction condition, ground condition with saturate and moisture state in Nak-Dong river sand. Also, in the group pile, the model tests were to investigate the effects on spacing-to-diameter ratio of pile, pile array, ratio of pile spacing, boundary condition of pile head and tip, eccentric load and ground condition. The maximum bending moment and deflection induced in active piles were found to be highly dependent on the relative density, pile construction condition, boundary condition of pile head and tip. Based on the results obtained, it was found that the decrease of lateral bearing capacity in saturated sand was in the range of 31% - 53% as compared with the case of dry sand. Also, in the group pile, a spacing-to-diameter of 6.0 seems to be large enough to eliminate the group effect for the case of relative density of 61.8%, and 32.8%, and then each pile in such a case behaves essentially the same as a single pile. In this study, the program is developed by using the modified Chang method which used p - y method and the exact solution of governing equation of pile and it can be used to calculate the deflection, bending moment and soil reaction with FDM in non-homogeneous soil. In comparing the modified Chang method with field test results, the predict results shows better agreement with measured results in field tests.

• Structural Engineering and Mechanics
• /
• 제40권4호
• /
• pp.583-594
• /
• 2011

In the present study, free vibration of an axially functionally graded (AFG) pile embedded in Winkler-Pasternak elastic foundation is analyzed within the framework of the Euler-Bernoulli beam theory. The material properties of the pile vary continuously in the axial direction according to the power-law form. The frequency equation is obtained by using Lagrange's equations. The unknown functions denoting the transverse deflections of the AFG pile is expressed in modal form. In this study, the effects of material variations, the parameters of the elastic foundation on the fundamental frequencies are examined. It is believed that the tabulated results will be a reference with which other researchers can compare their results.

• 한국지반공학회논문집
• /
• 제36권7호
• /
• pp.15-28
• /
• 2020

매입말뚝의 주면마찰력은 공벽에 주입되는 시멘트풀로 발휘되므로, 시멘트풀이 양생되기 이전에 수행되는 초기항타시험으로 매입말뚝의 주면마찰력을 평가할 수 없다. 또한, 재항타시험 시 항타에너지 부족으로 충분히 선단지지력이 발휘되지 않아 매입말뚝의 최종 지지력이 제대로 평가되지 않을 수 있다. 본 연구에서는 매입말뚝의 초기항타시험과 재항타시험의 결과를 조합하는 새로운 하중-침하량 곡선을 제안하고자 하였다. 현장에 시험말뚝을 매입말뚝공법으로 시공하였으며, 초기항타 및 재항타시험을 수행하고 동재하시험 결과에 대하여 CAPWAP(CAse Pile Wave Analysis Program) 분석을 수행하였다. 초기항타 시 선단 지지거동과 재항타 시 주면 지지거동을 조합한 말뚝 내 하중전이곡선을 가정하였으며, 하중-침하량 곡선을 새롭게 산정하였다. 또한 조합된 하중-침하량 곡선을 이용하여 시험말뚝의 지지력을 평가하였으며 이를 초기항타 및 재항타시험 결과와 비교 분석하였다. 분석 결과, 조합된 하중-침하량 곡선으로 산정된 지지력은 항타에너지 부족으로 인한 지지력 과소평가를 극복할 수 있는 것으로 나타났다. 또한, 가정된 하중전이곡선은 초기항타 및 재항타시험 결과와 비교했을 때 매입말뚝의 지지거동에 더 가까우므로, 조합된 하중-침하량 곡선을 이용함으로써 정재하시험 결과와 더 유사한 지지력을 산정할 수 있을 것으로 기대된다. 따라서, 본 연구에서 제안한 조합된 하중-침하량 곡선을 사용함으로써 매입말뚝의 동재하시험 시 지지력을 효과적으로 평가할 수 있다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2004년도 춘계학술발표회
• /
• pp.211-218
• /
• 2004

The objective of this study is to enhance the ultimate bearing capacity of piles embedded in marine clay by electrokinetic(EK). The focus of improvement is at interlace between soil and pile. A series laboratory test was performed in EK cell. In each of test, the pile in the centre as anode is surrounded by cathode and it was installed in the vicinity of pile with triangular layout. The pile was made by stainless and embedded with 30cm of depth. Afterward, the DC voltage was applied to electrode over period of time. It caused flowing water from anode to cathode, thus the soil in the center of box has higher bearing capacity value than in the side of box has. It is shown by increasing of un-drained shear strength(Cu) near the pile and also ultimate bearing capacity of pile increase after EK treatment. In the future work, the continuous of this study is finding the effective DC voltage and makes EK treatment more applicable in the field.

• 한국지진공학회논문집
• /
• 제21권5호
• /
• pp.255-264
• /
• 2017

Dynamic numerical simulation of pile-supported slab track system embedded in a soft soil and embankment was performed. 3D model was formulated in a time domain to consider the non-linearity of soil by utilizing FLAC 3D, which is a finite difference method program. Soil non-linearity was simulated by adopting the hysteric damping model and liner elements, which could consider soil-pile interface. The long period seismic loads, Hachinohe type strong motions, were applied for estimating seismic respose of the system, Parametric study was carried out by changing subsoil layer profile, embankment height and seismic loading conditions. The most of horizontal permanent displacement was initiated by slope failure. Increase of the embedded height and thickness of the soft soil layer leads increase of member forces of PHC piles; bending moment, and axial force. Finally, basic guidelines for designing pile-supported slab track system under seismic loading are recommended based on the analysis results.

• 한국지반환경공학회 논문집
• /
• 제16권7호
• /
• pp.23-33
• /
• 2015

본 연구는 차수가 요구되는 현장에 Sheet Pile을 적용하려고 하나 풍화암 등의 지반조건으로 인해 항타관입성의 제한이 있을 때 H-Pile로 보강된 Sheet Pile 흙막이 벽체를 적용하기 위한 수치해석 연구이다. Sheet Pile을 H-Pile로 보강한 S/H 복합파일의 거동을 규명하기 위하여 Sheet Pile의 규격 2종류와 H-Pile 3종류의 부재조건 변화, Sheet Pile과 H-Pile의 설치 근입심도 변화, H-Pile의 설치간격, 굴착조건 등을 변화시킨 101개의 경우에 대해 광범위한 수치해석을 실시하였다. 수치해석 결과, Sheet Pile SP-IIIA와 H-Pile H250, Sheet Pile SP-IV와 H-Pile H350의 조합에서 두 부재가 동시에 허용응력에 도달하거나 같은 응력비를 갖는 것으로 나타나 이 기성제품 조합이 효율적임을 알 수 있었으며, S/H 복합파일의 강성이 증가할수록 벽체의 수평변위가 감소하였고 S/H 복합파일 중 Sheet Pile의 근입심도가 안정성에 미치는 영향은 작은 것으로 나타나 Sheet Pile은 지지층 내 관입이 가능한 위치까지만 설치하여도 차수 및 벽체강성 증가의 목적을 달성할 수 있을 것으로 분석되었다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2000년도 봄 학술발표회 논문집
• /
• pp.167-172
• /
• 2000

In this study, the behaviors of a cast-in-situ concrete pile embedded in the weathered rock were analysed by a 3D numerical analysis using PENTAGON 3D and the results were compared with those of the field load test. The load-settlement relation and the load transfer relationship were evaluated from the numerical analysis. As a result, the load-settlement relation at the pile top and the axial load distribution with depth were predicted reasonably. And those results were similar with those of the field load test.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2001년도 봄 학술발표회 논문집
• /
• pp.371-378
• /
• 2001

The working load at pile is sometimes subjected to not only compression load but also lateral load and uplift forces. Pile foundation is essential and uplift load can be applied because of buoyancy, a typhoon, wind or seismic forces. This study was carried out to determine the uplift capacity of concrete pile foundation driven in clay. Pile was driven in clay, between pile and clay adhesion factor was estimated, and it is the mean value between the cast-in-situ-pile and steel pipe pile. When pile foundation is loaded for long time, creep behavior occurs. The behavior of creep is originated from the clay creep contacted with pile. The creep behavior of pile foundation embedded in clay is heavily depended on the thickness of clay around the pile shaft, pore water pressure in clay, and creep behavior of clay.

• Computers and Concrete
• /
• 제31권5호
• /
• pp.443-455
• /
• 2023

This is a research analyses on the bearing capacity at a pile tip embedded in rock. The aim is to propose a shape coefficient for an analytical solution and to investigate the influence of the plastic flow law on the problem. For this purpose, the finite difference method is used to analyze the bearing capacity of various types and states of rock masses, assuming the Hoek & Brown failure criterion, by considering both plane strain and an axisymmetric model. Different geometrical configurations were adopted for this analysis. First, the axisymmetric numerical results were compared with those obtained from the plane strain analytical solution. Then the pile shape influence on the bearing capacity was studied. A shape factor is now proposed. Furthermore, an evaluation was done on the influence of the plastic flow law on the pile tip bearing capacity. Associative flow and non-associative flow with null dilatancy were considered, resulting in a proposed correlation. A total of 324 cases were simulated, performing a sensitivity analysis on the results and using the graphic output of vertical displacement and maximum principal stress to understand how the failure mechanism occurs in the numerical model.

• 한국지반공학회논문집
• /
• 제21권5호
• /
• pp.111-122
• /
• 2005

암반에 근입된 대구경 현장타설말뚝에 대한 하중-침하량 특성을 조사하기 위하여 35개소에서 실시된 말뚝재하시험 결과를 분석하였다. 일반적으로 단단한 암반에 근입된 대구경 현장타설말뚝의 침하량은 대단히 미소하여 말뚝의 설계 시방서상에 제시된 말뚝의 전체침하량이나 잔류침하량에 대한 규정을 적용하여 극한하중을 결정할 수가 없다. 따라서 암반에 근입된 대구경 현장타설말뚝의 항복하중을 결정하기 위하여 항타말뚝을 대상으로 이전에 제시된 P-logS분석법을 적용하여 보았다. 적용결과, 이 방법은 기존의 다른 분석법인 P-S, logP-logS, S-logt 및 P-S분석법에 비하여 항복하중결정이 비교적 간편하고 정확하였다. 그리고 암반에 근입된 대구경 현장타설말뚝의 하중이 항복하중에 도달하기 전까지의 말뚝의 하중-침하량 관계를 나타낼 수 있는 회귀분석식이 제시되었다. 또한, 지지층의 종류와 암반 근입심도에 따른 말뚝의 침하거동특성도 조사하였다. 끝으로 현장말뚝재하시험결과에 대한 고찰을 통하여 암반에 근입된 현장타설말뚝의 항복하중을 결정할 수 있는 새로운 침하량 기준값이 제시되었다.