• Title, Summary, Keyword: 표준관입시험

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Determination of Wave Equation Soil Constants by Standard Penetration Test (표준관입시험을 통한 파동방정식 지반정수 산정법)

  • 김범상;김기영;조성민
    • Journal of the Korean Geotechnical Society
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    • v.18 no.4
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    • pp.45-53
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    • 2002
  • There are some previous studies on the determination wave equation soil constants by SPT. However, methods suggested in previous researches had such analytical defects as the non-uniqueness of solutions, long-time consuming in computation, and lacking of accuracy due to the limit of available point values in time domain. In this paper, a modified procedure is proposed to improve the accuracy of determination of wave equation soil constants. It is based upon the least-error approach which minimizes the sum of errors between the measured and the recalculated wave values in total time domain. Finally, its applicability was verified by analyzing measured data presented on the released references.

A Comparison of Soil Characteristics of Excavated Soils in Urban Area (도심지 굴착지반의 지반특성 비교)

  • Kim, Byungchan;Lee, JineHaeng
    • Journal of Korean Society of Disaster and Security
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    • v.10 no.1
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    • pp.35-42
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    • 2017
  • This is a comparative study on the characteristics of excavated soils, which is proceeded using soil strength parameter by literature, geotechnical investigation, standard penetration test by drilling, and downhole test by borehole at six sites in urban areas. The results of these site surveys are used as basic data for the evaluation and development of prediction of ground subsidence risk. Geotechnical properties are estimated with the result of standard penetration test-N value and literature. The dynamic geotechnical characteristics are also estimated with top-down seismic exploration at borehole.

CFD Analysis of Underwater Standard Penetration Test Equipment (해저 표준관입시험 장비의 밀폐형 항타부 CFD 해석)

  • Ko, Jin Hwan;Jang, In Sung;Kim, Woo Tae;Kwon, O Soon;Baek, Won Dae
    • Journal of Ocean Engineering and Technology
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    • v.26 no.6
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    • pp.33-38
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    • 2012
  • In our study, a closed-type penetration unit for standard penetration test (SPT) equipment was developed in order to operate in an underwater environment. This type causes energy dissipation, mainly due to the small gap between an airtight case and moving hammer. The dissipation was estimated through a CFD analysis. The computed dissipated energy was less than 1.2% compared to the potential energy of the hammer with the given gap. Subsequently, the impact energy of the underwater SPT equipment was within 1.2% of that for the SPT equipment on land.

Preparation of Probabilistic Liquefaction Hazard Map Using Liquefaction Potential Index (액상화 가능 지수를 활용한 확률적 액상화 재해도)

  • Chung, Jae-won;Rogers, J. David
    • Journal of The Korean Society of Civil Engineers
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    • v.34 no.6
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    • pp.1831-1836
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    • 2014
  • Probabilistic liquefaction hazard map is now widely needed for engineering practice. Based on the Liquefaction Potential Index (LPI) calculated from liquefied and non-liquefied cases, we attempted to estimate probabilities of liquefaction induced ground failures using logistic regression. We then applied this approach for the regional area. LPIs were calculated based on 273 Standard Penetration Tests in the floodplains in the St. Louis area, USA and then interpolated using cokriging with the covariable of peak ground acceleration. Our result shows that some areas of $LPI{\geq}5$, due to soft soil layers and shallow groundwater table, appear probabilities of ground $failure{\geq}0.5$.

A Study on the Shear Modulus of Weathered Granite Soil by Pressuremeter Tests (공내재하시험을 이용한 화강풍화토의 전단계수 산정)

  • Kim, Jong-Soo;Lee, Kyu-Hwan;Lee, Chang-Tok;Lee, Song
    • Geotechnical Engineering
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    • v.13 no.6
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    • pp.95-106
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    • 1997
  • A pressuremeter is an expandable tube which is placed in the soil, and then expanded under controlled condition against the soil. From this test a pressure expansion curve of the soil can be obtained. However soil disturbance during the test has significant influence on the results of tests. A general governing equation for pressuremeter test can be theoretically derived on the basis of the hyperbolic soil model and the cavity expansion theory. The curve fitting technique was used to establish the pressure-strain curve without disturbance of soil during testing. This interpretation makes use of both the loading and unloading portions of the test. An interpretation methodology is described and illustrated with pressuremeter test data carried out in the weathered granitic soil to estimate initial shear modulus. Standard penetration test is a very common site investigation technique in Korea. Therefore the blow counts of standard penetration test are discussed by comparing them with initial shear modulus.

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LPI-based Assessment of Liquefaction Potential on the West Coastal Region of Korea (액상화 가능 지수를 이용한 국내 서해안 지역의 액상화 평가)

  • Seo, Min-Woo;Sun, Chang-Guk;Oh, Myoung-Hak
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.4
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    • pp.1-13
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    • 2009
  • Liquefaction is a significant threat to structures on loose saturated sandy soil deposits in the event of an earthquake, and can often cause catastrophic damage, economic loss, and loss of life. Nevertheless, the Korean peninsula has for a long time been recognized as a safe region with respect to the hazard of liquefaction, as the peninsula is located in a moderate seismicity region, and there have been no reports of liquefaction, with the exception of references in some historical documents. However, some earthquakes that have recently occurred in different parts of the world have led to liquefaction in non-plastic silty soils, a soil type that can be found in many of the western coastal areas of Korea. In this study, we first present procedures for evaluating the liquefaction potential, and calculate the liquefaction potential index (LPI) distribution at two western coastal sites using both piezocone penetration test (CPTu) data and standard penetration test (SPT) data. The LPI is computed by integrating liquefaction potential over a depth of 20m, and provides an estimate of liquefaction-related surface damage. In addition, we compared the LPI values obtained from CPTu and SPT, respectively. Our research found that the CRR values from CPTu were lower than those from the SPT, particularly in the range between 40 and 120 for the corrected tip resistance, (qc1N)CS, from the CPTu, or in the range of CRR less than 0.23, resulting in relatively high LPI values. Moreover, it was observed that the differences in the CRR between the two methods were relatively higher for soils with high fine contents.

Analysis of Pile Head Lateral Load-Deflection Behavior of Steel-Concrete Composite Drilled Shafts (강관합성 현장타설말뚝 머리의 수평하중-변위 거동 분석)

  • Lee, Yong-An;Chung, Moon-Kyung;Park, Jae-Hyun;Lee, Ju-Hyung
    • Journal of the Korean Geotechnical Society
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    • v.27 no.12
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    • pp.97-106
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    • 2011
  • To analyze the lateral load-deflection behavior of steel-concrete composite drilled shafts, a series of lateral pile load tests were performed. The test results were compared with the results from various analytical methods for lateral pile behaviors using the coefficients of subgrade reaction ($k_h$) estimated by pressuremeter test (PMT) and standard penetration test (SPT). As a result, it was found that the analytical methods using the $k_h$ estimated by SPT N value were not suitable for evaluating the pile head lateral load-deflections of the piles within the allowable deflection. However, the methods using the $k_h$ calculated from PMT were able to represent the initial lateral behavior at the head of the piles fairly well. Also, the method by the pressuremeter curve, which was applied directly to the p-y curve of the piles, offered a reasonable lateral behavior estimation by applying the correction factor to the pile materials.

A Study on Evaluation of Modulus of Horizontal Subgrade Reaction through Field Test and Numerical Analysis (현장시험과 수치해석을 통한 수평지반반력계수 산정에 관한 연구)

  • Kang, Byungyun;Park, Minchul;Lee, Sihyung;Jang, Kisoo;Koo, Jagap;Park, Kyunghan
    • Journal of the Korean Geoenvironmental Society
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    • v.17 no.4
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    • pp.5-15
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    • 2016
  • For achieving stability and economic construction at a retaining wall construction site, quantitative parameters of soil properties with excavation steps coincides with the actual field site. The main parameters of retaining wall design such as deformation modulus and modulus of horizontal subgrade reaction are common with N value of standard penetration test. Therefore, this study is compared and analyzed about the mutual relationship which is SPT, PBT and PMT for overcoming inconsistency of the existing retaining wall design generalized. In addition, modulus of horizontal subgrade reaction and reduction factor with excavation steps are proposed through back analysis of elasto-plasticity and finite element method with actual field monitoring data. Finally, it is purpose that parameter errors are reduced for applying effective retaining wall design at a construction small and medium-sized.

Evaluation of Spudcan Penetration/Extraction Behavior in Uniform Sand and Clay (모래와 점토 단일지반에서의 스퍼드캔 관입/추출 거동 평가)

  • Yoo, Jin-Kwon;Park, Duhee;Kang, Jaemo
    • Journal of the Korean Geotechnical Society
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    • v.33 no.3
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    • pp.17-28
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    • 2017
  • We performed laboratory spudcan penetration and extraction tests considering various geometries. Jumunjin sand, representative standard sand in South Korea, and kaolinite were used for uniform sand and clay layers, respectively. The measured vertical bearing and pull-out capacities were compared to empirical equations for shallow foundations. The results showed good agreement between measured and calculated bearing capacity from laboratory test and previous study at shallow depths. The effect of spudcan geometry is shown to depend on site condition. The influence of a sharp spigot is not significant in clays. The slope of the spudcan surface is shown to influence the pull-out capacity. The characteristics of spudcan penetration and extraction behavior considering various geometries can be a useful reference for determining spudcan geometries.