• 제목/요약/키워드: embedded pile

검색결과 202건 처리시간 0.026초

Impact of adjacent excavation on the response of cantilever sheet pile walls embedded in cohesionless soil

  • Singh, Akshay Pratap;Chatterjee, Kaustav
    • Geomechanics and Engineering
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    • 제30권3호
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    • pp.293-312
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    • 2022
  • Cantilever sheet pile walls having section thinner than masonry walls are generally adopted to retain moderate height of excavation. In practice, a surcharge in the form of strip load of finite width is generally present on the backfill. So, in the present study, influence of strip load on cantilever sheet pile walls is analyzed by varying the width of the strip load and distance from the cantilever sheet pile walls using finite difference based computer program in cohesionless soil modelled as Mohr-Coulomb model. The results of bending moment, earth pressure, deflection and settlement are presented in non-dimensional terms. A parametric study has been conducted for different friction angle of soil, embedded depth of sheet pile walls, different magnitudes and width of the strip load acting on the ground surface and at a depth below ground level. The result of present study is also validated with the available literature. From the results presented in this study, it can be inferred that optimum behavior of cantilever sheet pile walls is observed for strip load having width 2 m to 3 m on the ground surface. Further as the depth of strip load below the ground surface increases below the ground level to 0.75 times excavation height, the bending moment, settlement, net earth pressure and deflection decreases and then remains constant.

모래지반에 매입된 날개없는 석션앵커의 인발력에 대한 원심모형실험 (Centrifuge Model Tests on the Pullout Capacity of Embedded Suction Anchor without Flanges in Sand layer)

  • 김경오;김유석;고부현
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2005년도 지반공학 공동 학술발표회
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    • pp.517-520
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    • 2005
  • The embedded suction anchor(ESA) is and anchor that is driven by a suction pile. The cross-sectional shape of the ESA anchor is circle. Its diameter is the same as that of the suction pile that is used to drive it into the seafloor. For the installation, the anchor is attached to the tip of the suction pile and then driven as a unit with the pile by and applied suction pressure. Once the ESA anchor reaches the desired depth, the pile is retrieved by applying a positive pressure. Finally, only the ESA anchor remains in the soil layer. This paper presents the results of centrifuge model tests to investigate ESA pullout capacity. The main parameters that have effects on the pullout capacity of ESA may include g-level, embedded depth, direction of loading, and loading point. The results of tests show that the pullout loading capacities increase as the loading point shift toward the tip of the anchors for a given loading direction. They also indicate that the loading point associated with the maximum pullout loading capacity is located at approximately 67 percent of the anchor length from the top for the horizontal load.

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좌굴을 고려한 액상화 지반에 근입된 말뚝의 파괴거동 분석 (Analysis of Failure Behavior of Pile Embedded in Liquefiable Soil Deposits considering Buckling Instability)

  • 한진태;조종석;황재익;김명모
    • 한국지진공학회:학술대회논문집
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    • 한국지진공학회 2006년도 학술발표회 논문집
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    • pp.105-112
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    • 2006
  • Liquefaction-induced lateral spreading has been the most extensive damage to pile foundations during earthquakes. However, a case of pile failure was reported despite the fact that a large margin of safety factor was employed in their design. This means that the current seismic design method of pile is not agreeable with the actual failure mechanism of pile. Newly proposed failure mechanism of pile is a pile failure based on buckling instability. In this study, failure behavior of pile embedded in liquefied soil deposits was analyzed considering lateral spreading and buckling instability performing 1g shaking table test. As a result, it can be concluded that the pile subjected to excessive axial loads ($near\;P_{cr}$) can fail by buckling instability during liquefaction. When lateral spreading took place in sloping grounds, lateral spreading increased lateral deflection of pile and reduced the buckling load, promoting more rapid collapse. In addition, buckling shape of pile was observed. In the ease of pile buckling, hinge formed at the middle of the pile, not at the bottom. And in sloping grounds, location of hinge got loiter compared with level ground because of the effects of lateral spreading.

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사질토 지반에서 단일 강성말뚝의 수평거동에 대한 시공방법의 영향 (Effect of Pile Construction on Lateral Behavior of Single Rigid Pile in Sand)

  • 김병탁;김영수;서인식
    • 한국지반공학회논문집
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    • 제15권6호
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    • pp.29-44
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    • 1999
  • 본 논문은 균질 및 비균질의 사질토 지반에서 항타 시공된 단일 강성말뚝의 수평거동에 대한 모형실험 결과들을 고찰하였다. 본 연구의 목적은 말뚝의 수평거동 특성에 대한 말뚝 시공상태 (Driven & Embedded), 말뚝 근입길이에 대한 하부지반의 두께비 (H/L),그리고 지반의 상대밀도의 영향에 관하여 실험적인 연구를 수행하고 이러한 영향들을 정량화 할 수 있는 실험결과를 얻었다. 모형 실험 결과들에 의하면, 수평거동은 느슨한 균질지반에서 시공방법에 상당히 의존하는 것으로 나타났다. 말뚝시공시 항타방법에 의존할 경우 균질지반에서는 느슨한 지반일수록 그리고 비균질 지반 $(E_{h1}/E_{h2}/=0.18)$에서는 상부층 두께가 클수록 수평변위 감소에 상당한 효과를 얻을 수 있으나, 최대 휨모멘트 감소는 수평변위 감소와 정반대의 결과를 나타냈다. 수평변위 측면에서, 매입말뚝에 대한 항타말뚝의 변위비 $(y_{Driven}y_{Embedded})$는 균질지반의 각 상대 밀도에 대하여 0.65-0.88 $(D_r=90%)$와 0.38-0.65 (D$_{r}$=61.8%)의 범위로 그리고 비균질지반에서 0.6-0.88 의 범위로 나타났다. 또한, 본 연구에서는 $y_D/y_E \;와\; NBM_D/MBM_E$에 대한 항타고와 H/L의 영향들을 모형실험 결과들로부터 실험식으로 제안하였다.

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원커팅 철근보강 PHC 말뚝의 속채움 콘크리트 부착파괴 성능 (Slip Failure Strength of Infilled Concrete with Reinforced PHC Pile by One-Cutting Method)

  • 천영수;심영종;박종배
    • 토지주택연구
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    • 제2권4호
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    • pp.553-558
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    • 2011
  • 말뚝두부와 기초판의 연결방법으로서 기존의 강선남김방식은 시공성이 좋지 않고, 말뚝두부에 파손 및 균열이 발생할 가능성이 높을 뿐만 아니라 현장 인명사고가 자주 발생하여 최근에는 대안적인 방법으로서 원커팅에 의한 철근보강 방식이 제안되어 사용되고 있다. 하지만 이러한 방법들은 역학적인 성능규명에 의하여 그 상세가 구체적으로 제안 또는 검증된 사례가 없다. 이 연구는 원커팅 철근보강 방식에 있어서 최적 보강상세를 제안 할 목적으로 후 타설된 말뚝 내 속채움 콘크리트와 말뚝간의 전단마찰 저항력의 부족으로 인한 파괴를 실험을 통하여 규명하고, 적정 채움 깊이를 제안하였다. 실험결과에 근거하여 말뚝 부착파괴 강도를 안전측의 값으로 0.4MPa를 가정한다면, 부착파괴 이전에 철근이 항복에 도달하도록 하기 위해서 속채움 콘크리트의 깊이는 최소한 PHC 450과 PHC 500의 경우 600mm 이상, PHC 600의 경우 1,000mm 이상 확보하여야 할 것으로 판단된다.

Dynamic response of pipe pile embedded in layered visco-elastic media with radial inhomogeneity under vertical excitation

  • Cui, Chun Y.;Meng, Kun;Wu, Ya J.;Chapman, David;Liang, Zhi M.
    • Geomechanics and Engineering
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    • 제16권6호
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    • pp.609-618
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    • 2018
  • A new mechanical model for predicting the vibration of a pipe pile embedded in longitudinally layered visco-elastic media with radial inhomogeneity is proposed by extending Novak's plain-strain model and complex stiffness method to consider viscous-type damping. The analytical solutions for the dynamic impedance, the velocity admittance and the reflected signal of wave velocity at the pile head are also derived and subsequently verified by comparison with existing solutions. An extensive parametric analysis is further performed to examine the effects of shear modulus, viscous damping coefficient, coefficient of disturbance degree, weakening or strengthening range of surrounding soil and longitudinal soft or hard interbedded layer on the velocity admittance and the reflected signal of wave velocity at the pile head. It is demonstrated that the proposed model and the obtained solutions provide extensive possibilities for practical application compared with previous related studies.

광섬유 센서에 의한 말뚝 하중전이 측정 (Measurement of Pile Load Transfer using Optical Fiber Sensors)

  • 오정호;이원제;이우진
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 1999년도 가을 학술발표회 논문집
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    • pp.397-404
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    • 1999
  • It is essential to measure load transfer mechanism of pile to check the appropriateness of assumptions made for design purpose and to continuously monitor the behavior of pile foundation. Through many attempts to monitor the behavior of super-structure in civil engineering area using several optical fiber sensors have been made, application of optical fiber sensor technology on pile foundation has not been tried up to now. Load transfer of model piles during compression loading was measured by optical fiber sensors and compared with the measurement by strain gauges. Fiber Bragg Grating(FBG) sensor system was used since it has many advantages, such as easy multiplexing, high sensitivity, and simple fabrication. Besides the model pile tests, uniaxial tension test of steel bar and compression tests of mortar specimen were carried out to evaluate the performance of FBG sensors in embedded environments. The shift of refilming wavelength due to the strain in FBG sensor is converted to the strain at sensor location and the dependence between them is 1.28 pm/${\mu}$ strain. FBG sensors embedded in model pile showed a better survivability than strain gauges. Measured results of load transfer by both FBG sensors and strain gauges were similar, but FBG sensors showed a smoother trend than those by strain gauge. Based on the results of model pile test, it was concluded that the use of FBG sensor for strain measurement in pile has a great potential for the analysis of pile load transfer.

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Response of passively loaded pile groups - an experimental study

  • Al-abboodi, Ihsan;Sabbagh, Tahsin Toma;Al-salih, Osamah
    • Geomechanics and Engineering
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    • 제20권4호
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    • pp.333-343
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    • 2020
  • Preventing or reducing the damage impact of lateral soil movements on piled foundations is highly dependent on understanding the behavior of passive piles. For this reason, a detailed experimental study is carried out, aimed to examine the influence of soil density, the depth of moving layer and pile spacing on the behavior of a 2×2 free-standing pile group subjected to a uniform profile of lateral soil movement. Results from 8 model tests comprise bending moment, shear force, soil reaction and deformations measured along the pile shaft using strain gauges and others probing tools were performed. It is found that soil density and the depth of moving layer have an opposite impact regarding the ultimate response of piles. A pile group embedded in dense sand requires less soil displacement to reach the ultimate soil reaction compared to those embedded in medium and loose sands. On the other hand, the larger the moving depth, the larger amount of lateral soil movement needs to develop the pile group its ultimate deformations. Furthermore, the group factor and the effect of pile spacing were highly related to the soil-structure interaction resulted from the transferring process of forces between pile rows with the existing of the rigid pile cap.

Numerical Analysis of Pile-Soil Interaction under Axial and Lateral Loads

  • Khodair, Yasser;Abdel-Mohti, Ahmed
    • International Journal of Concrete Structures and Materials
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    • 제8권3호
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    • pp.239-249
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    • 2014
  • In this paper, the analysis of a numerical study of pile-soil interaction subjected to axial and lateral loads is presented. An analysis of the composite pile-soil system was performed using the finite difference (FD) software LPILE. Two three dimensional, finite element (FE) models of pile-soil interaction have been developed using Abaqus/Cae and SAP2000 to study the effect of lateral loading on pile embedded in clay. A lateral displacement of 2 cm was applied to the top of the pile, which is embedded into the concrete pile cap, while maintaining a zero slope in a guided fixation. A comparison between the bending moments and lateral displacements along the depth of the pile obtained from the FD solutions and FE was performed. A parametric study was conducted to study the effect of crucial design parameters such as the soil's modulus of elasticity, radius of the soil surrounding the pile in Abaqus/Cae, and the number of springs in SAP2000. A close correlation is found between the results obtained by the FE models and the FD solution. The results indicated that increasing the amount of clay surrounding the piles reduces the induced bending moments and lateral displacements in the piles and hence increases its capacity to resist lateral loading.

파동방정식에 근거한 매입말뚝의 동적 분석 (Dynamic Analyses on Embedded Piles Based on Wave Equation)

  • 서미정;박종배;박용부;이종섭
    • 한국지반공학회논문집
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    • 제31권11호
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    • pp.5-13
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    • 2015
  • 저소음, 저진동 공법으로 널리 사용되고 있는 매입말뚝도 과거와 달리 정재하시험 보다는 동재하시험을 이용한 지지력 확인시험을 많이 수행하고 있다. 본 연구의 목적은 선단부 근처의 지반조건이 상이한 곳에 시공된 두본의 매입말뚝의 최종 경타동안에 획득된 힘과 속도 파형을 대하여 동적해석을 수행하여 매입말뚝의 지지 및 관입 거동을 분석하는 것이다. 파동방정식을 근거로 하는 동재하시험 분석 프로그램으로는 CAPWAP과 WEAP 등이 있으며 본 논문에서는 실제 현장에서 동재하시험을 수행한 매입말뚝을 CAPWAP과 WEAP을 이용하여 분석하였다. 동재하시험에서 측정된 데이터를 분석한 CAPWAP의 입력값과 결과값, 힘-속도 그래프 파형을 분석하였고, WEAP의 입력조건을 변화시키며 CAPWAP 결과와 유사한 WEAP 결과를 도출하였다. 이 때, 선단부 근처의 지반조사 결과를 고려하여 관입 깊이에 따른 N치의 분포가 지수 함수 형태이면 입력조건 중 Toe quake의 값이 작으며 이로 인해 큰 지지력이 얻어지고, 관입 깊이에 따른 N치의 분포가 선형 함수 형태이면 이와 반대되는 결과가 얻어진다. 또한 정확한 값을 구하기 어려운 해머 및 말뚝 쿠션의 강성 입력값으로서 500kN/mm 이하인 값을 추천할 수 있었다. 본 연구는 WEAP으로 실제 측정된 데이터를 분석하는 CAPWAP과 유사한 결과를 얻을 수 있으며, WEAP을 이용하여 매입말뚝의 지지력 평가가 가능함을 보여준다.