• Title/Summary/Keyword: energy piles

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Winkler Springs (p-y curves) for pile design from stress-strain of soils: FE assessment of scaling coefficients using the Mobilized Strength Design concept

  • Bouzid, Dj. Amar;Bhattacharya, S.;Dash, S.R.
    • Geomechanics and Engineering
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    • v.5 no.5
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    • pp.379-399
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    • 2013
  • In practice, analysis of laterally loaded piles is carried out using beams on non-linear Winkler springs model (often known as p-y method) due to its simplicity, low computational cost and the ability to model layered soils. In this approach, soil-pile interaction along the depth is characterized by a set of discrete non-linear springs represented by p-y curves where p is the pressure on the soil that causes a relative deformation of y. p-y curves are usually constructed based on semi-empirical correlations. In order to construct API/DNV proposed p-y curve for clay, one needs two values from the monotonic stress-strain test results i.e., undrained strength ($s_u$) and the strain at 50% yield stress (${\varepsilon}_{50}$). This approach may ignore various features for a particular soil which may lead to un-conservative or over-conservative design as not all the data points in the stress-strain relation are used. However, with the increasing ability to simulate soil-structure interaction problems using highly developed computers, the trend has shifted towards a more theoretically sound basis. In this paper, principles of Mobilized Strength Design (MSD) concept is used to construct a continuous p-y curves from experimentally obtained stress-strain relationship of the soil. In the method, the stress-strain graph is scaled by two coefficient $N_C$ (for stress) and $M_C$ (for strain) to obtain the p-y curves. $M_C$ and $N_C$ are derived based on Semi-Analytical Finite Element approach exploiting the axial symmetry where a pile is modelled as a series of embedded discs. An example is considered to show the application of the methodology.

A Study of Applicability of PDT(Pulse Discharge Technology) Pile to Kyung-Geon Rail Road and the bedding Construction of a new port in Busan (경전선 복선전철 및 부산신항 노반건설공사 중 PDT말뚝 적용성 연구)

  • Hur, Eok-Jun;Park, Jae-Myung;Yun, Su-Dong;Kim, Tae-Hoon
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.1203-1208
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    • 2007
  • In the past decades, complain about ground vibration and noise induced by pile driving has been quickly increased. Because of that, auger drilled piling methods have frequently used specially in urban area. However, the present auger drilled piling methods induce inevitable ground disturbance as well as a certain degree of vibration and noise due to the final hammering. For these reasons, a new auger drilled piling method is required to be developed. This paper introduces PDT(Pulse Discharge Technology) piling method and presents the characteristics of bearing capacity. The PDT piling method is to install in-situ piles using electric power so called Pulse. The pile installed by PDT appears to be able to develop shaft and end bearing capacity efficiently. This paper introduces PDT(Pulse Discharge Technology) piling method, which is the 512nd new construction technology. The PDT piling method is to install in-situ piles using electrical power so called Pulse power. The pulse power is physical value that indicates the energy change per unit time(dE/dt). Since the pulse power is to push ground, using the pulse power is enable a hole to be expanded as well as the ground to be improved by compaction. Therefore, The pile installed by PDT appears to be able to develop shaft and end bearing capacity efficiently. In this study, couples of pile loading tests were carried out to figure out whether or not the PDT piling method is applicable to constructions like rail road facility. As a result, it was concluded that the PDT piling technique meet the requirements for such a rail road related construction.

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Model Tests on a Plastic Pipe Pile for the Analysis of Noise, Energy Transfer Effect and Bearing Capacity due to Hammer Cushion Materials (해머 쿠션 재질에 따른 모형말뚝의 소음, 에너지 전달효율 및 지지력 분석)

  • Lim, Yu-Jin;Hwang, Kwang-Ho;Park, Young-Ho;Lee, Jin-Gul
    • Journal of the Korean Geotechnical Society
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    • v.22 no.12
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    • pp.33-43
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    • 2006
  • Driving tests using model plastic piles with different hammer cushion materials were performed in order to evaluate the efficiency of energy transfer ratio from the hammer, degree of vibration of the surrounding ground and noise due to impacting. A small pile driving analyzer (PDA) was composed using straingages and Hopkinson bar which is measuring force signal and pile-head velocity. The hammer cushion (cap block) materials used for the model driving tests were commercial Micarta, plywood, polyurethane, rubber (SBR) and silicone rubber. The highest energy transfer ratio was obtained from Micarta in the same soil and driving conditions. Micarta was followed by polyurethane, plywood, rubber and silicone in descending order. The more efficient energy transfdr ratio of the hammer cushion materials became, the bigger average noisy (sound) level was found. In addition, Micarta and polyurethane provided bigger bearing capacities than other materials compared in the same soil and driving conditions in which the static loading tests were performed at the end of driving.

Scaled Test on the Behavior of the Toe of Drilled Shaft on Rock Mass (암반에 근입된 말뚝의 선단 거동 특성에 관한 축소모형시험 연구)

  • Park, Woan-Suh;Choi, Se-Keun;Jeon, Seok-Won;Han, Yong-Hee
    • Proceedings of the Korean Geotechical Society Conference
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    • 2008.03a
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    • pp.1166-1171
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    • 2008
  • Despite of the increasing number of the application of drilled shaft piles in construction site, most studies on pile capacity have been focused on the side shear resistance. But it is common that the drilled shaft is socketed on the rock so as to use its bearing resistance. The prediction of the end movement and characteristics of the bearing capacity of the pile is great important as well. Therefore, a series of scaled model tests were carried out in order to study the characteristics of the bearing capacity on rock mass. The material of the test block was cement mortar which was mixed with sand, cement and water, and the size of a test block size was $240{\times}240{\times}240mm$. The axial load was applied by a miniaturized pile of 45mm in diameter and flat jacks and steel plate were used for confinement to simulate the real underground loading conditions. The relation of load-displacement was measured in various different conditions of rock mass such as strength, discontinuity of the rock mass and in-situ stress, so q-w curves of the end of the pile were presented for each condition.

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The Fracture Behavior Analysis in Concrete Quay Deck Subjected to Collision of Ship (선박충돌에 의한 콘크리트 안벽의 파괴거동분석)

  • Lee, Rae-Chul;Yhim, Sung-Soon
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.1 no.1
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    • pp.75-87
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    • 1997
  • To study the behavior a deck when it was collide with the ship approaching to the deck to berth, it was analyzed the effect zone by the ship collision which consists of deck slab and PC piles of the quay. The numerical technique is used to simulate the behavior of the deck when the ship hit the expansion joint of deck between the deck slabs. The failure behavior and zone of the deck are determinated by the comprehensive numerical study. The impact energy by the ship is also evaluated. It is concluded that these numerical analysis gave a reasonable estimation of the remedial area of the deck damaged by ship collision.

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Study on Thermal Behavior and Design Method for Coil-type PHC Energy Pile (코일형 PHC 에너지파일의 열적 거동 및 설계법에 관한 연구)

  • Park, Sangwoo;Sohn, Jeong-Rak;Park, Yong-Boo;Ryu, Hyung-Kyou;Choi, Hangseok
    • Journal of the Korean Geotechnical Society
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    • v.29 no.8
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    • pp.37-51
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    • 2013
  • An energy pile encases heat exchange pipes to exchange thermal energy with the surrounding ground formation by circulating working fluid through the pipes. An energy pile has many advantages in terms of economic feasibility and constructability over conventional Ground Heat Exchangers (GHEXs). In this paper, a coil-type PHC energy pile was constructed in a test bed and its thermal performance was experimentally and numerically evaluated to make a preliminary design. An in-situ thermal response test (TRT) was performed on the coil-type PHC energy pile and its results were compared with the solid cylinder source model presented by Man et al. (2010). In addition, a CFD numerical analysis using FLUNET was carried out to back-analyze the thermal conductivity of the ground formation from the Ttype PHC energy RT result. To study effects of a coil pitch of the coil-type heat exchange pipe, a thermal interference between the heat exchange pipes in PHC energy piles was parametrically studied by performing the CFD numerical analysis, then the effect of the coil pitch on thermal performance and efficiency of heat exchange were evaluated. Finally, an equivalent heat exchange efficiency factor for the coil-type PHC energy pile in comparison with a common multiple U-type PHC energy pile was obtained to facilitate a preliminary design method for the coil-type PHC energy pile by adopting the PILESIM2 program.

Ultimate Capacity of Guardrail Supporting Pile Subjected to Lateral Impact Load Using Centrifuge Model Test (원심모형실험을 통한 차량방호울타리 지지말뚝의 수평방향 충격하중에 대한 극한지지력)

  • Yun, Jong Seok;Lee, Min Jy;Choo, Yun Wook
    • Journal of the Korean Geotechnical Society
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    • v.35 no.11
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    • pp.25-36
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    • 2019
  • The safety barrier is installed on road embankment to prevent vehicles from falling into road side slope. Among the safety barrier, flexible guardrails are usually installed. The flexible guardrail generally consists of a protection cross-beam and supporting in-line piles. These guardrail piles are installed nearby slope edge of road embankment because the side area of the road is much narrow. The protection cross-beam absorbs impact energy caused by vehicle collision. The pile-soil interaction also absorbs the rest of the impact energy and then, finally, the flexible guardrail system resists the impact load. This paper aims to investigate the pile-soil interaction subjected to impact load using centrifuge model tests. In this study, a single pile was installed in compacted residual soil and loaded under lateral impact load. An impact loading system was designed and developed available on centrifuge tests. Using this loading system, a parametric study was performed and the parameters include types of loading and ground. Finally, the ultimate bearing capacity of supporting pile under impact load was analyzed using load-displacement curve and soil reaction pressure distributions at ultimate were evaluated and compared with previous studies.

Structural Capacity of High Strength Steel Pipe Pile After Pile Driving (고강도 강관말뚝의 항타후 구조성능 분석)

  • La, SeungMin;Yoo, Hankyu
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.6C
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    • pp.251-258
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    • 2011
  • Steel pipe piles have been used as various deep foundation materials for a long time. Recent increase in steel material cost has made engineers reluctant in using it even with its good quality and ease of construction. Therefore when constructing with steel pipe pile, the decision to reuse the excessive pile length that is cut off from the designed pile head elevation after pile driving can be cost saving. This has caused many constructors to reuse the pile leftovers with new piles, but the absence of quantitative structural capacity behaviors of steel pipe pile after pile driving or appropriate countermeasures and standards in reusing steel pipe pile has resulted in wrong applications, pile structural integrity problems, inappropriate limitation of reusable pile length, etc. The structural performance analysis between a new pile and a pile that has undergone working state and ultimate state stress level during pile driving was performed in this research by means of comparing the results between the dynamic pile load test, tensile load test, charpy energy test and fatigue test for high strength steel of $440N/mm^2$ yield strength. Test results show that under working load conditions the yield strength variation is less than 2% and for ultimate load conditions the variation is less than 5% for maximum total blow count of 3000. The results have been statistically analyzed to check the sensitivity of each factors involved. From the test results, reusability of steel pipe pile lies not in the main pipe yield strength deviation but in the reduction of absorb energy, strength changes and quality control at the welded section, shape deformation and local buckling during pile driving.

Performance of KICT-type Large Penetration Test (LPT) (한국형 대형관입시험 장비의 개발 및 현장 적용성 평가)

  • Kim, Young-Seok;Kim, Young-Chin;Hong, Sung-Wan;Kang, Jae-Mo;Ji, Wan-Goo
    • Proceedings of the Korean Geotechical Society Conference
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    • 2007.09a
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    • pp.603-610
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    • 2007
  • It is well known that the standard penetration test (SPT) has been used in all over the world to get geotechnical properties of the ground. However, it is difficult to apply the SPT to the dense sand, gravel, weathered rock, etc. For the application of the SPT in these grounds, it is necessary to change in the diameter and the impact energy of the SPT. For the improvement of site investigation technology, Large Penetration Testing device (KICT-type LPT) was developed and applied to the in situ condition. The drop height and weight of the hammer in developed system were decided as 760 mm and 150 kg, respectively. Semi-auto hammer drop system identical with KS F2307 and JI A1259S was adopted. And the developed sampler has the inner diameter of 63 mm and the length of 500 mm with the adjustment of energy ratio to the SPT of 1.5. The hammer energy level was measured during the performance of the KICT-type LPT using SPI system (quality control system from driven piles).

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Effect of CPR Foundation Reinforcement Assessed by Compressive Loading Tests (CPR 공법의 압축재하시험을 통한 기초지반의 보강효과)

  • Kang, Seong-Seung;Kim, Jung-Han;Noh, Jeongdu;Ko, Chin-Surk
    • The Journal of Engineering Geology
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    • v.29 no.3
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    • pp.211-222
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    • 2019
  • This study evaluates the yield load and allowable bearing capacity of ground in compressive loading tests to confirm the effect of CPR foundation reinforcement. The average compressive strength of the injection materials was higher than the planned compressive strength. Standard penetration tests for each stratum showed that foundation reinforcement improved the average N values, thereby increasing the bearing capacity of the ground. Compressive loading tests on two CPR piles revealed that the total and net settlement due to the maximum load exceed that permissible for the CPR pile diameter. The yield load and allowable bearing capacity calculated by the settlement criterion and the load-settlement curves varied greatly with the method applied. Therefore, it seems to be necessary to determine the optimum value through comprehensive analysis after applying various yield load calculation methods.