• Title/Summary/Keyword: piles

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An Analytical Study on Inclination of Vertical Piles (연직말뚝의 경사도 오차에 관한 해석적 연구)

  • 장정욱;박춘식;최차석
    • Proceedings of the Korean Geotechical Society Conference
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    • 2003.03a
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    • pp.463-468
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    • 2003
  • This paper studied the effects of inclination of piles on pile behaviors. The following are the conclusions of this study. (1) When all the piles are inclined to a same direction, the piles reaction, maximum moment and horizontal displacement of footing increase as the angle of inclination increases. (2) When the piles of each opposite side are inclined symmetrically, the vertical reaction either increases or decreases in proportion to the angle of inclination. In this case, the vertical reaction of inclined piles decreases but the vertical reaction of non-Inclined piles increases.

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Lateral Behavior of Hybrid Composite Piles Using Prestressed Concrete Filled Steel Tube Piles (긴장력이 도입된 콘크리트 충전 강관말뚝을 사용한 복합말뚝의 수평거동 특성)

  • Park, No-Won;Paik, Kyu-Ho
    • Journal of the Korean Geotechnical Society
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    • v.34 no.12
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    • pp.133-143
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    • 2018
  • Concrete filled steel tube (PCFT) piles, which compose PHC piles inside thin steel pipes, were developed to increase the flexural strength of the pile with respect to the horizontal load. In order to compare the flexural strength of PCFT pile with that of steel pipe pile, several flexural tests were performed on the PCFT and steel pipe piles with the same diameter and the P-M curves for both piles were constructed by the limit state design method. Four test piles were also installed and lateral pile load tests were performed to compare the lateral load capacities and lateral behaviors of the hybrid composite piles using PCFT piles and the existing piles such as HCP and steel pipe piles. The flexural test results showed that the flexural strength of PCFT piles was 18.7% higher than that of steel pipe piles with thickness of 12mm and the same diameter, and the mid-span deflection of piles was 50% lower than that of steel pipe piles at the same bending moment. From the P-M curves, it can be seen that the flexural strength of PCFT piles subjected to the vertical load is greater than that of steel pipe piles, but the flexural strength of PCFT piles subjected to the pullout load is lower than that of steel pipe piles. In addition, field pile load tests showed that the PCFT hybrid composite pile has 60.5% greater lateral load capacity than the HCP and 35.8% greater lateral load capacity than the steel pipe pile when the length of the upper pile in hybrid composite piles was the same.

A LSTM-based method for intelligent prediction on mechanical response of precast nodular piles

  • Chen, Xiao-Xiao;Zhan, Chang-Sheng;Lu, Sheng-Liang
    • Smart Structures and Systems
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    • v.30 no.2
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    • pp.209-219
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    • 2022
  • The determination for bearing capacity of precast nodular piles is conventionally time-consuming and high-cost by using numerous experiments and empirical methods. This study proposes an intelligent method to evaluate the bearing capacity and shaft resistance of the nodular piles with high efficiency based on long short-term memory (LSTM) approach. A series of field tests are first designed to measure the axial force, shaft resistance and displacement of the combined nodular piles under different loadings, in comparison with the single pre-stressed high-strength concrete piles. The test results confirm that the combined nodular piles could provide larger ultimate bearing capacity (more than 100%) than the single pre-stressed high-strength concrete piles. Both the LSTM-based method and empirical methods are used to calculate the shift resistance of the combined nodular piles. The results show that the LSTM-based method has a high-precision estimation on shaft resistance, not only for the ultimate load but also for the working load.

Settlement analysis of pile cap with normal and under-reamed piles

  • Kumar, Madisetti Pavan;Raju, P. Markandeya;Jasmine, G. Vincent;Aditya, Mantini
    • Computers and Concrete
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    • v.25 no.6
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    • pp.525-535
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    • 2020
  • The use of pile foundations has become more popular in recent years, as the combined action of the pile cap and the piles can increase the bearing capacity, reduce settlement, and the piles can be arranged so as to reduce differential deflection in the pile cap. Piles are relatively long, slender members that transmit foundation loads through soil strata of low bearing capacity to deeper soil or rock strata having a high bearing capacity. In this study analysis of pile cap with considering different parameters like depth of the pile cap, width and breadth of the pile cap, type of piles and different types of soil which affect the behaviour of pile cap foundation is carried out by using Finite Element Software ANSYS. For understanding the settlement behaviour of pile cap foundation, parametric studies have been carried out in four types of clay by varying pile cap dimensions with two types of piles namely normal and under-reamed piles for different group of piles. Furthermore, the analysis results of settlement and stress values for the pile cap with normal and under-reamed piles are compared. From the study it can be concluded that settlement values of pile cap with under-reamed pile are less than the settlements of pile cap with normal pile. It means that the ultimate load bearing capacity of pile cap with under-reamed piles are greater than the pile cap with normal piles.

대구경 소켓경사반력말뚝의 인발거동에 관한 연구

  • 최용규;김상옥;정창규;정성기;김상일
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.11a
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    • pp.277-284
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    • 2000
  • Using the large diameter (D = 2,500mm, L = 40m) batter steel pipe piles, designed as compression piles but used as reaction piles during the static compression load test of socketed test piles (D = 1,000mm, L = 40m), static pile load tests for large diameter instrumented rock-socketed piles were performed. The reaction steel pipe piles were driven 20m into the marine deposit and weathered rock layer and then l0m socketed with reinforced concrete through the weathered rock layer and into hard rock layer. Steel pipe and concrete in the steel pile part, and concrete and rebars in the socketed parts were instrumented to measure strains in each part. The pullout amounts of reaction pile heads were also measured with LVDT. During the static pile load test, total compressional load of about 20MN was loaded on the head of test piles, but load above 20MN was not loaded due to lack of loading capacity of loading system. Over the course of the study, maximum pullout amount up to 7mm was measured in the heads of reaction piles when loaded op to 10MN and 1mm of pullout amount was measured. More than 85% of pullout load was transfered in the residual weathered rock layer and about 10% in the soft rock layer, which was somewhat different transfer mechanism in the static compressional load tests.

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An Experimental Study on the Behavior of Miscopiles installed in Weathered Weak Rock (풍화암 지반에 설치된 소구경말뚝의 거동에 관한 연구)

  • 박성재;정경환;이세훈
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.10a
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    • pp.389-396
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    • 1999
  • In this study compressive and tensile load tests have been performed to investigate reinforcing effect and load transfer mechanism of small diameter piles installed in the foundation soil for the marine suspension bridge. Load tests were carried out on steel plate with diameters of 50cm, 100cm and 150cm varying loads starting from 39 tons up to 314 tons. Small diameter piles were proved to behavior like as friction piles and loads were not transmitted to the bottom of piles. From pull-out tests, the uplift capacity of small diameter piles was largely influenced by reinforcing materials compared to frictional resistance between piles and adjacent soils. The bearing capacity of small diameter piles appeared to be higher than the ultimate bearing capacity evaluated using static formulae. The load carrying capacity of small diameter piles was superior to the bored piles with a similar size. Thus, ultimate bearing capacity estimated from static formulae can provide conservative designs and thereby resulting in economic disadvantages. A further study to accumulate data regarding various soil conditions is recommended for an improved estimation of bearing capacity of piles with small diameter.

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Effect on Dynamic Behavior of Group Piles with Changing Thickness of Pile Cap

  • Jeong, Kusic;Ahn, Sangro;Kim, Seongho;Ahn, Kwangkuk
    • Journal of the Korean GEO-environmental Society
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    • v.19 no.7
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    • pp.5-11
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    • 2018
  • Instead of a single pile, group piles are usually used for the pile foundation. If the earthquake occurs in the ground where group piles are installed, dynamic behavior of group piles are affected not only by interaction of piles and the ground movement but also by the pile cap. However, in Korea, the pile cap influence is not taken account into the design of group piles. Research on dynamic behavior of group piles has been performed only to verify interaction of piles and the ground and has not considered the pile cap as a factor. In this research, 1g shaking table model tests were performed to verify the thickness of the pile cap affects dynamic behavior of group piles that were installed in the ground where the earthquake would occur. The test results show that, as thickness of the pile cap increased, acceleration and horizontal displacement of the pile cap decreasd while vertical displacement of the pile cap increased. The results also showed that, among the group files tested, acceleration, horizontal displacement, and vertical displacement of the bearing pile are smaller than those of the friction pile.

The Behavior of Bearing Capacity of Steel Pipe Piles Reinforced by Super Injection Grouting at Pile Tip (S.I.G 공법으로 선단보강된 강관말뚝의 지지거동)

  • Park, Young-Ho;Kim, Nag-Young;Yook, Jeong-Hoon;Choi, Jin-O
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.20-27
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    • 2004
  • Reinforced twice than width of foundation with SIC under steel piles drived in cohesion soil and in the coal-limestone which heavily fractured. To analyze behaviour characteristic of steel piles, load transfer test was performed to steel piles attached with strain gauges to axial direction. After it passed 49days, dynamic load test was performed to set-up effect of steel piles bearing capacity. The results of test were compared to each other. According to the results, as the skin friction of steel pile was on the same condition, end bearing capacity of steel piles established on SIC solid of cemented milk in cohesion soil was three times than steel piles established on SIG solid of cemented milk in heavily fractured coal- limestone. After piles were driven and passes 49days, in case of piles on SIG solid of comented milk in cohesion soil the increaes of allowable bearing capacity was 442.9% and allowable bearing capacity of piles on SIG solid of cemented milk in heavily fractured coal-limestone increased 22.4%.

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Characteristics of Stress-Displacement on Uplift Loaded Group Piles (인발력을 받는 무리말뚝의 응력-변위 특성)

  • Lee, Jun-Dae;Ahn, Byeong-Cheol
    • Journal of the Korean Society of Safety
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    • v.20 no.3 s.71
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    • pp.152-157
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    • 2005
  • This experimental study was devoted to investigate skin friction of H group piles with uplift loading conditions in granite soil under laboratory test. Model piles made of steel embedded in weathered granite soil were used in this study. Pile arrangements($2{\times}2,\;3{\times}3$), pile space(2D, 4D, 6D), and soil density($D_r=40%,\;80%$) were tested. The main results obtained from the model tests can be summarized as follows. The series of tests found that ultimate uplift load and displacement for group piles were increased as piles space ratio increases to $D_r=40%$ of soil density. In the relative density of $D_r=80%$, bearing capacity for group piles was greater than for single pile. In the relative density of $D_r=40%$, the theoretical value of skin friction for group piles was greater than practical value. In the relative density of $D_r=80%$, both theoretical and practical value of skin friction for group piles were increased as piles space ratio increases.

Static pile load test and load trasfer measurement for large diameter piles. (대구경 말뚝정재하시험 및 하중전이 측정사례)

  • 최용규
    • Proceedings of the Korean Geotechical Society Conference
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    • 2000.03a
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    • pp.107-141
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    • 2000
  • Large diameter piles can be defined as piles with diameter of at least 0.76 m (2.5 ft). In bridge foundation, large diameter piles have been used as pier foundations and their use has been increased greatly. In this study, static pile load tests for large diameter piles peformed in Kwangan Grande Bridge construction site were introduced. Also, various sensor installation methods for several types of piles (that is, open-ended steel pipe pile, drilled shafts and socketed pipe piles), pipe axial load measuring method, load transfer analysis method and pile load test results (pile-head load - settlement curve, and pile axial load distribution curve along the pile depth) were introduced.

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