• Title/Summary/Keyword: Pile type ground improvement

Search Result 15, Processing Time 0.024 seconds

Application of Soil-Cement Piles to the Ground Improvement of Harbor Structures (소일-시멘트 파일을 이용한 항만구조물의 말뚝식 지반개량 적용성)

  • Lee, Seong-Hun;Kwon, Oh-Yeob;Shin, Jong-Ho
    • Journal of the Korean Geotechnical Society
    • /
    • v.29 no.11
    • /
    • pp.29-47
    • /
    • 2013
  • This study undertook research on the sections of 90 harbor structures which applied a pile-type soil improvement using the soil-cement pile and then, determined the minimum replacement rate for each section, showing sufficient stability in all relevant studies including numerical analysis. The reliability of the numerical analysis was verified by a centrifuge model test. As a result of the study, it was revealed that when the foundation soil is too soft ($s_u$ = under 15 kPa), it is unsuitable to apply a pile-type ground improvement to a soil improvement regardless of types of super structures. And a pile-type soil improvement was found to be suitable for a harbor structure with the relative stiffness ratio (n) of less than 50~75 at a maximum and the 2~3 MPa strength of the soil-cement pile. Furthermore the governing factor for the minimum replacement rate for the pile-type soil improvement was turned out to be the allowable horizontal displacement. Therefore, the primary review to see the applicability of the pile-type soil improvement requires the evaluation of horizontal displacements.

Experimental Study on Soft Ground with DCM Column (DCM 타설 지반에 관한 실내모형실험)

  • Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
    • /
    • v.19 no.3
    • /
    • pp.35-44
    • /
    • 2020
  • This study described the result of laboratory model tests, in order to compare the improvement effect of the DCM column installed on the soft ground according to DCM column type. In the laboratory model test, the non-reinforced type and the 3 types of DCM column were applied, and the behavior (settlement, lateral flow) of soft ground was evaluated under the surcharge load condition for each type. The settlement evaluation result showed that the settlement of soft ground without DCM column occurred rapidly under the low load condition, but the settlement of the soft ground with the DCM column had relatively small settlement. The evaluation result of lateral flow in the soft ground showed that the soft ground with DCM column had lower lateral displacement than the soft ground without DCM column. Especially, the lateral displacement under the same load condition decreased in the order of pile type, wall type, and grid type. Therefore, it confirmed that the improvement effect of soft ground was excellent when the DCM of grid type was applied for settlement and lateral flow.

Horizontal Behavior Characteristics of Umbrella-Type Micropile Applied in Sandy Soil Subjected to Seismic Motion (사질토 지반에 설치된 우산형 마이크로파일의 지진 시 수평거동 특성)

  • Kim, Soo-Bong;Son, Su Won;Kim, Jin Man
    • Journal of the Korean GEO-environmental Society
    • /
    • v.21 no.7
    • /
    • pp.5-16
    • /
    • 2020
  • Currently, the seismic design standards have been strengthened due to the occurrence of the Gyeongju and Pohang earthquake, and seismic performance evaluation of existing facilities is being conducted. It aims to secure a seismic performance effect during earthquakes by improving the micro-pile method, which can be constructed in limited confined places while minimizing damage to existing facilities. The improvement method is to construct all the piles in the square-tray-type plate on the top of the pile by constructing the slope pile in the form of an umbrella around the vertical pile, the main pillar. In this paper, the numerical analysis was performed to analyze the horizontal displacement behavior of an umbrella-type micropile for various real-measurement seismic waves in sandy soil. As a result of numerical analysis, the softer the ground, the better the effect of horizontal resistance of umbrella-type micropile. The horizontal displacement reduction effect was pronounced when the embedded depth was 15 m or more at the same ground strength, and it was found to be effective in earthquakes if it was settled on the ground with an N value of 30 or more. The embedded depth and horizontal displacement suppression effect of the micropile was proportional. Generally, the weaker the ground, the greater the displacement suppression effect. Umbrella-type micropile had a composite resistance effect in which the vertical pile resists the moment and inclined pile resists the axial force.

A Case Study on the Application of Gravel Pile in Soft Ground (Gravel Pile의 현장적용을 위한 시험시공 사례연구)

  • 천병식;고용일;여유현;김백영;최현석
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2000.02a
    • /
    • pp.32-41
    • /
    • 2000
  • Sand drain as a vertical drainage is widely used in soft ground improvement Recently, sand, the principal source of sand drain, is running out. The laboratory model tests were carried out to utilize gravel as a substitute for sand. Though which the characteristics of gravel are compared to those of sand for engineering purpose. Two cylindrical containers for the model test were filled with marine clayey soil from the west coast of Korea with a column in the center, one with sand, the other with gravel. Vibrating wire type piezometers were installed at the distance of 1.0D, 1.5D and 2.0D from the center of the column. The characteristics of consolidation were studied with data obtained from the measuring instrument place on the surface of the container. The parameter study was performed on the marine clayey soil before and after the test in order to verify the effectiveness of the improvement. The clogging effect was checked at various depth in gravel column after the test. In-situ tests area was divided into two areas by material used. One is Sand Drain(SD) and Sand Compaction Pile(SCP) area, the other is Gravel Drain(GD) and Gravel Compaction Pile(GCP) area. Both areas were monitored to obtain the information on settlement, pore water pressure and bearing capacity by measuring instruments for stage loading caused by embankment. The results of measurements were analyzed. According to the test results, the settlement was found to be smaller in gravel drain than in sand drain. The increase in bearing capacity by gravel pile explains the result. The clogging effect was not found in gravel column. It is assumed that gravel is relatively acceptable as a drainage material. Gravel is considered to be a better material than sand for bearing capacity, and it is found that bearing capacity is larger when gravel is used as a gravel compaction pile than as a gravel drain.

  • PDF

Behavior of Variable Cross-Section Soft Ground Reinforced Foundation in Soft Grounds (연약지반에 적용된 변단면 연약지반보강기초의 거동분석)

  • Kim, Khi-Woong;Kim, Dong-Wook;Jo, Myoung-Su
    • Journal of the Korean Geosynthetics Society
    • /
    • v.15 no.4
    • /
    • pp.89-96
    • /
    • 2016
  • Compressive axial behavior of the variable cross-section soft ground reinforced foundation is investigated from the field load test results at ${\bigcirc}{\bigcirc}$ construction site in Incheon city. Variable cross-section soft ground reinforced foundation is a type of partial-displacement pile formed by mixing bidding material with in situ soils to obtain a rigid and strong variable cross-section column in a relatively soft ground. The foundations are usually constructed as a group; however in this study, only single foundation was installed and tested under compressive axial load on foundation head. For the comparison of the variable cross-section soft ground reinforced foundation axial behavior, behavior of typical Pretensioned spun high strength concrete (PHC) pile constructed on a relatively soft ground near the surface was analyzed. It was concluded that variable cross-section soft ground reinforced foundation efficiently resists against axial load with sufficient stiffness and strength within a considerable range of axial load magnitude.

Reinforcement of Building Foundation by the Low Slump Mortar Grout (저유동성 몰탈형 주입재에 의한 건물기초보강)

  • 천병식;고용일;권형석
    • Proceedings of the Korean Geotechical Society Conference
    • /
    • 2000.11a
    • /
    • pp.71-76
    • /
    • 2000
  • In generally, grouting consists of injecting a suspension or solution into the voids of soils. The low slump mortar grout has been used in America since 1950's. The Compaction Grouting, the injection of a very stiff under relatively high pressure, form a cylinderical grout support pile. The grout generally does not enter soil pores but remains in homogeneous mass that gives controlled displacement either to compact loose soils, or for lifting of structures, or both. In this paper, on the case of the reinforcement construction of 00 plant that the foundation's bearing capacity is insufficient and is to reinforce the foundation, a study has been peformed to analyze the effectiveness of the ground improvement. The bearing capacity of the Compaction Pile has been verified by the S.P.T and the settlement of the improved ground has been monitored rising the magnetic extensometer.

  • PDF

Verification of Applicability of Hybrid CFFT Pile for Numerical Analysis (수치해석을 통한 FRP 콘크리트 합성말뚝 적용성 평가)

  • Kim, HongTaek;Lee, MyungJae;Park, JeeWoong;Yoon, SoonJong;Han, YeonJin
    • Journal of the Korean GEO-environmental Society
    • /
    • v.12 no.8
    • /
    • pp.59-67
    • /
    • 2011
  • The interaction of the ground deformation and composite piles, which is made of fiber glass, was analyzed for the effective pile application under vertical loads. This study was performed to conduct experimentation test and propose the material characteristics of the new type concrete injection circular FRP pile for the improvement of the defect of CFFT-Concrete composition piles and FRP-Concrete composition piles(FRP reinforced column direction). Additionally, in order to analyze the behaviour characteristics of composite pile and steel pile the numerical analyses were carried out.

A Study on Ground Heave Characteristics of Soft Ground with DCM (DCM으로 개량된 연약점토지반의 지반융기에 관한 고찰)

  • You, Seung-Kyong;Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
    • /
    • v.19 no.4
    • /
    • pp.75-84
    • /
    • 2020
  • This paper described the analysis result on heaving of soft ground with DCM column type, based on the results of laboratory model tests on the soft ground with DCM column. The heave characteristics of the soft ground were evaluated according to the application of DCM column in soft ground. The results showed that the heaving of soft ground without DCM column occurred rapidly when the lateral deformation of soft ground increased significantly under the 4th load step condition. In addition, the heaving of soft ground in final load step caused tensile failure of the ground surface. The maximum heaving of the soft ground with the DCM column occurred in the final load step, and the heaving quantity decreased in the order of pile, wall, and grid type. Especially, the soft ground with DCM of grid type effectively resisted ground heaving, even if it was extremely failure in the bottom ground of embankment. The results of the maximum heaving according to the measurement point showed that the heaving of the soft ground with DCM of grid type was 3.1% and 1.6% compared to that of the pile and wall type at the location of LVDT-1, and the heaving of the LVDT-2 position was 1.0% and 2.1%, respectively.

The Numerical Analysis on the Behaviour of Combined Sheet Pile in the Reclaimed Ground Mixed by Sandy Soil and Clayey Soil (사질토와 점성토가 혼재하는 해안 매립지반에서 조합형 Sheet Pile의 거동에 관한 해석적 연구)

  • Kim, Byung-Il;Kim, Young-Sun;Han, Sang-Jae;Park, Eon-Sang
    • Journal of the Korean Geosynthetics Society
    • /
    • v.19 no.3
    • /
    • pp.9-21
    • /
    • 2020
  • In this study, the design method of the combined sheet pile was considered in the coastal landfill where sandy and clayey soils are mixed, and the behavior in excavation was analyzed. It was confirmed from the elasto-plastic analysis that the predicted behavior of the temporary facilities of earth retaining differs according to the type of the combined sheet pile method (Built up, Interlocking, Welding) and the analysis method (soldier pile method, continuous wall method). In the case of sheet pile member force, the results of the continuous wall analysis method predicted the most conservative results. When the stress ratio (calculation/allowance) of each member was analyzed based on the maximum member force of the combined sheet pile method, the maximum value was obtained for bending moment in the side pile and combined stress in the case of the strut. As a result of finite element analysis, the member force of the side pile was the largest in the short-term effective stress analysis condition, while the compressive force of the strut was large in the consolidation analysis. When comparing the results of the elasto-plastic analysis and the finite element analysis, the shear force of the side pile and the axial force of the strut were greatly evaluated in the elasto-plastic analysis, and the bending moment of the side pile was the largest in the short-term effective stress condition of the finite element analysis. In addition, the displacement of the side pile was predicted to be greater in the finite element analysis than in the elasto-plastic analysis.

A Study on Behavior Characteristics of Soft Ground by DCM Arrangement Type (DCM 배치 형상에 따른 연약지반 거동 특성에 관한 연구)

  • You, Seung-Kyong;Lee, Jong-Young;Hong, Gigwon
    • Journal of the Korean Geosynthetics Society
    • /
    • v.20 no.4
    • /
    • pp.125-131
    • /
    • 2021
  • This study described the relationship of settlement-lateral displacement and settlement-heaving according to the DCM type using the model test results, in order to evaluate the behavioral characteristics of the soft ground improved with DCM. As a result, it was found that the total settlement of the model ground was relatively small in the soft ground, to which the DCM was applied, and the settlement was less in the order of the grid type, wall type, and pile type under the same load conditions. This trend was also the same for the lateral displacement and heaving. In addition, the relationship between settlement and lateral displacement of soft ground was analyzed to be similar to that of previous study (Leroueil et al., 1990). Therefore, the DCM of grid type was evaluated to be superior to other types for lateral flow and heaving in the improvement effect of soft ground.