• Title, Summary, Keyword: DCPT

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A Study on the Development of Design Chart for Drilled Shaft Socketed into Weathered Zone Using DCPT (Driving Cone Penetrometer Test) (DCPT를 이용한 풍화대 소켓 현장타설말뚝의 설계도표 개발에 관한 연구)

  • Jung, Sung-Min;Kwon, Oh-Sung;Lee, Jong-Sung;Lee, Min-Hee;Choi, Yong-Kyu
    • Journal of the Korean Geotechnical Society
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    • v.26 no.5
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    • pp.5-13
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    • 2010
  • For the development of design chart for drilled shafts socketed into weathered zone, the 6 bi-directional pile load tests with load transfer measurements done in two in-situ sites were performed. Also, DCPTs were performed in each test point. Maximum unit skin frictions and maximum unit end bearing capacities from pile load test results were analyzed. Inter-relationships between DCPT's characteristics were also analyzed. In the soils, the inter-relationships of maximum unit skin friction and DCPT appeared so low. But in the weathered zones, inter-relationships between maximum unit skin friction / maximum unit end bearing capacity and DCPT were so high that the coefficient of correlation is over 0.70.

Fundamental Study on Establishing the Subgrade Compaction Control Criteria of DCPT with Laboratory Test and In-situ Tests (실내 및 현장실험를 통한 DCPT의 노상토 다짐관리기준 정립에 관한 기초연구)

  • Choi, Jun-Seong
    • International Journal of Highway Engineering
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    • v.10 no.4
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    • pp.103-116
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    • 2008
  • In this study, in-situ testing method, Dynamic Cone Penetration Test(DCPT) was presented to establish a new compaction control criteria with using mechanical property like elastic modulus instead of unit weight for field compaction control. Soil chamber tests and in-situ tests were carried out to confirm DCPT tests can predict the designed elastic modulus after field compaction, and correlation analysis among the DCPT, CBR and resilient modulus of sub grade were performed. Also, DCPT test spacing criteria in the construction site was proposed from the literature review. In the result of laboratory tests, Livneh's equation was the best in correlation between PR of DCPT and CBR, George and Pradesh's equation was the best in the predicted resilient modulus. In the resilient modulus using FWD, Gudishala's equation estimates little larger than predicted resilient modulus and Chen's equation estimates little smaller. And KICT's equation estimates the modulus smaller than predicted resilient modulus. But using the results of laboratory resilient modulus tests considering the deviatoric and confining stress from the moving vehicle, the KICT's equation was the best. In the results of In-situ DCPT tests, the variation of PR can occur according to size distribution of penetrate points. So DCPT test spacing was proposed to reduce the difference of PR. Also it was shows that average PR was different according to subgrade materials although the subgrade was satisfied the degree of compaction. Especially large sized materials show smaller PR, and it is also found that field water contents have influence a lot of degree of compaction but a little on the average PR of the DCPT tests.

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A Study on the Developement of Korean Driving Cone Penetrometer Test(DCPT) Method (한국형타격콘관입시험법의 개발에 관한 연구)

  • Jung, Sung-Min;Kwon, Oh-Sung;Lee, Jong-Sung;Lee, Min-Hee;Choi, Yong-Kyu
    • Journal of the Korean Geotechnical Society
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    • v.27 no.8
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    • pp.17-30
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    • 2011
  • A variety of in-situ geotechnical investigation methods are currently used to measure the properties of each site, but in-situ tests for "Intermediate Geomaterial (IGM)", which is the transitional geomaterial between soil and rock, have only limited application. In the United States, "The Texas Cone Penetrometer Test (TCPT)", which is the geotechnical investigation technology for IGM, is utilized to create foundation designs. This paper introduces "The Driving Cone Penetrometer Test (DCPT)", which can be performed using general geotechnical investigation equipment and also analyzes the correlation between various in-situ geotechnical investigation methods by applying DCPT on the ground. The results showed that the correlation between the driving cone penetrometer test (DCPT) and standard penetration test (SPT) was quite high. Additionally, the scope of DCPT properties was wide, depending on soil types.

A Study on Numerical Modeling of Dynamic CPT using Particle Flow Code (입자결합모델을 이용한 동적콘관입시험(DCPT)의 수치해석 모델링에 관한 연구)

  • You, Kwang Ho;Lee, Chang Su;Choi, Jun Seong
    • International Journal of Highway Engineering
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    • v.16 no.2
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    • pp.43-52
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    • 2014
  • PURPOSES : To solve problems in current compaction control DCPT(Dynamic Cone Penetrometer Test), highly correlated with various testing methods, simple, and economic is being applied. However, it、s hard to utilize DCPT results due to the few numerical analyses for DCPT have been performed and the lack of data accumulation. Therefore, this study tried to verify the validation of numerical modeling for DCPT by comparing and analyzing the results of numerical analyses with field tests. METHODS: The ground elastic modulus and PR(Penetration Rate) value were estimated by using PFC(Particle Flow Code) 3D program based on the discrete element method. Those values were compared and analyzed with the result of field tests. Also, back analysis was conducted to describe ground elastic modulus of field tests. RESULTS : Relative errors of PR value between the numerical analyses and field tests were calculated to be comparatively low. Also, the relationship between elastic modulus and PR value turned out to be similar. CONCLUSIONS : Numerical modeling of DCPT is considered to be suitable for describing field tests by carrying out numerical analysis using PFC 3D program.

An Analysis on Co-relationships Between In-situ Investigation Methods and End Bearing Capacity of A Drilled Shaft Socketed into the Weathered Zone (풍화대소켓 현장타설말뚝의 극한단위선단지지력과 원위치 지반조사방법들과의 상관관계 분석)

  • Choi, Yongkyu;Kwon, Oh Sung;Lee, Jong Seong;Choi, Sung Soon;Jung, Sung Min
    • Journal of The Korean Society of Civil Engineers
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    • v.30 no.2C
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    • pp.95-107
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    • 2010
  • To calculate the end bearing capacity of a drilled Shaft socketed into the rockmass, the unconfined compression strength could be used. But it is difficult to find the unconfined compression strength because it is impossible to get undisturbed samples in weathered soils and rocks. So, to calculate the end bearing capacity, the existing bearing formula could not be used. In this study, for five zones (near pile tip, tip~lower 1D, tip~lower 2D, upper 1D~lower 1D, upper 1D~lower 2D), the relationships between the characteristic values of in-situ tests(SPT, DCPT PMT, BST) and the end bearing capacity of drilled shafts were analysed. As a result, DCPT results were represented the best credibility. Also, a design chart of end bearing capacity using DCPT was suggested.

Correlation Analysis between DCPT Value and SPT Value (동적콘관입시험값과 표준관입시험값의 상관성 분석)

  • Lee, Bongjik;Lee, Jongkyu
    • Journal of the Korean Geoenvironmental Society
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    • v.15 no.8
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    • pp.23-30
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    • 2014
  • In-situ penetration tests have been widely used in geotechnical engineering for site investigation in support of analysis and design. Standard Penetration Test (SPT) and Dynamic Cone Penetration Test (DCPT) are typical dynamic sounding. DCPT was originally developed as an alternative for evaluating the properties of subgrade soils. The main advantages of DCPT are that it is fast, inexpensive, and it is particularly useful in delineating areas of weak soils overlying stronger strata and in quickly assessing the variability of the soil conditions. But lack of standardization is main reason that this test method has not been advanced more in recent years. In this study, it is clarified the correlation with the SPT blow count, N from DCPT data using big DCP eqipment. Regression analysis and correlationship analysis were conducted with the data from relationship between SPT and DCPT. The analysis results showed that the convert fact are in the range of 1.12~1.31 with variation with soil property.

Analysis of Correlation among Various Compaction Evaluation Methods for Estimating of the Bearing Capacity on Subgrades (노상토의 지지력 평가를 위한 다짐평가기법의 상관성 분석)

  • Lee, Joonyong;Jeoung, Jae-Hyeung;Choi, Changho;Kim, Jin-Young;Jin, Hyunwoo
    • Journal of the Korean Geosynthetics Society
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    • v.14 no.4
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    • pp.45-58
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    • 2015
  • Even though the plate bearing test (PBT) to evaluate the load baring capacity and the field density test to evaluate the relative density are mainly used for quality control of soil compaction in Korea, use of the dynamic cone penetrometer test (DCPT) and the dynamic plate bearing test (DPBT) considering economic feasibility, rapidity, and suitability for field conditions increase to use for quality control of soil compaction. In this study, bearing capacity and relative density of subgrade with thickness of 20 cm, 30 cm, and 40 cm are estimated using PBT, DCPT, DPBT and field density test in three field compaction tests, and the relationship among various compaction evaluation methods is analyzed and discussed.

Shear Wave Velocity Estimation of Railway Roadbed Using Dynamic Cone Penetration Index (동적 콘 관입지수를 이용한 철도노반의 전단파속도 추정)

  • Hong, Won-Taek;Byun, Yong-Hoon;Choi, Chan Yong;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.31 no.11
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    • pp.25-31
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    • 2015
  • Elastic behavior of the railway roadbed which supports the repeating dynamic loads of the train is mainly affected by the shear modulus of the upper roadbed. Therefore, shear wave velocity estimation of the uniformly compacted roadbed can be used to estimate the elastic behavior of the railway roadbed. The objective of this study is to suggest the relationship between the dynamic cone penetration index (DCPI) and the shear wave velocity ($V_s$) of the upper roadbed in order to estimate the shear wave velocity by using the dynamic cone penetration test (DCPT). To ensure the reliability of the relationship, the dynamic cone penetration test and the measurement of the shear wave velocity are conducted on the constructed upper roadbed. As a method for measurement of the shear wave velocity, cross hole is used and then the dynamic cone penetration test is performed at a center point between the source and the receiver of the cross hole. As a result of the correlation of the dynamic cone penetration index and the shear wave velocity at the same depths, the shear wave velocity is estimated as a form of involution of the dynamic cone penetration index with a determinant coefficient above 0.8. The result of this study can be used to estimate both the shear wave velocity and the strength of the railway roadbed using the dynamic cone penetrometer.

Settlement Restraint of Soft Ground by Low Slump Mortar Injection (저유동설 몰탈주입에 의한 연약지반의 침하억제 효과)

  • 천병식;여유현;정영교
    • Journal of the Korean Geotechnical Society
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    • v.17 no.6
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    • pp.53-67
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    • 2001
  • In this study the pilot test of CGS as injection method by low slump mortar was performed and the results were analyzed in order to find out the application of this method and effect of settlement restraint. The site far pilot test is adjacent to apartments supported by pile foundations. Sand drain method was performed previously as countermeasures against settlement, but settlement occur continuously because this ground is very soft. Site investigations such as SPT, DCPT and vane shear test were performed to determine the characteristics of ground improvement. Field measurements and FDM analysis were performed on purpose to find out the displacement of ground during injection works. From the results of this study, CGS method can be optimized by the control of diagram, space, depth, injection material, and injection pressure. CGS improved soft ground compositely by the bearing effect of CGS columns and reinforcement of adjacent ground. Considering that increase of N value is about 2.1, CGS can be considered as an effective method to increase the bearing capacity as well as to stop the settlement of soft ground. It is also expected to be economic and effective in improvement of ground when it is used in applicable sites.

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