• Title, Summary, Keyword: 표준관입시험

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Ratio of Hammer Energy and Dynamic Efficiency of Standard Penetration Test (표준관입 시험 해머의 에너지비와 동적효율)

  • Lee, Chang-Ho;Lee, Woo-Jin
    • Journal of the Korean Geotechnical Society
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    • v.21 no.9
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    • pp.5-12
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    • 2005
  • SPT hammer energy and its delivery are hon to influence the N value. The SPT hammer energy is classified into theoretical energy, velocity energy, rod energy and dynamic efficiency. In this study, the rod energy and the velocity energy are measured directly by PDA and Digital Line-Scan Camera which are most widely used type of SPT apparatus in Korea. The Dynamic efficiency is calculated through measured data. As the results of this study, the averages of rod energy ratio of donut, safety and automatic hammer are measured at 49.57, 61.60, and at $87.04\%$ by FV method. The averages of hammer velocity of donut, safety and automatic hammer are measured at $3.177{\pm}0.872$, $3.385{\pm}0.681$, and at $3.651{\pm}0.550$ m/s by Digital Line-Scan Camera, with the dynamic efficiencies at 0.732, 0.801, and 0.973 respectively.

Ideas for Drawing Proper Drilling Logs (합리적인 시추주상도 작성에 관한 소고)

  • 최성순;최수철;김태욱
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.13-33
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    • 2003
  • 시추조사는 설계 및 시공을 위한 기본적인 조사이며 조사자는 지층을 정확히 판단하고 시추주상도를 매개체로하여 이를 설계자와 시공자에게 전달하여야 한다. 많이 개선되었다고는 하지만 시추주상도의 내용이 작성자 또는 작성회사별로 양식과 기재방법이 다른 경우가 많아 시추주상도의 역할이 반감되는 경우가 많다. 본 고에서는 조사업계에 종사한 경험을 바탕으로 합리적인 시추주상도 작성을 위해 국내외의 시추주상도 양식을 비교하고 표준안을 제시하였으며 기재방법의 통일을 기하기 위한 개선 사항을 제시하였다.

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Estimation of End Bearing Capacity of SDA Augered Piles on Various Hearing Stratums (지지지반의 종류별 SDA매입말뚝의 선단지지력 산정)

  • Hong, Won-Pyo;Chai, Soo-Geun
    • Journal of the Korean Geotechnical Society
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    • v.23 no.5
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    • pp.111-129
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    • 2007
  • The standard construction manual of the SDA(Separated Doughnut Auger) piling method was proposed so that the resisting capacity of the augered piles could work effectively. 405 dynamic pile load tests and 30 static pile load tests were performed for 265 test piles, which were installed by the SDA piling method in 33 sites in Korea. The results of the pile load tests showed that the end bearing capacity of the SDA augered piles depended on the property of various soil stratums and did not agree with ones estimated by the existing formula based on several standard design codes. On the basis of the pile load test results, four formulas were presented according to bearing stratums to estimate quantitatively the unit end bearing capacity of the SDA augered piles. The formulas for the unit end bearing capacity of piles on soils or weathered rocks were related to N-value given by SPT(Standard Penetration Test), while the unit end bearing capacity on bedrock was suggested to be more than 1500 $tf/m^2$. The presented formulas were compared with the existing formulas, which were presented by several standard design codes to design the augered piles. In order to use correctly the presented formulas, the quality of Standard Penetration Test should be controlled precisely. Also it is desirable to choose a pilot construction site, where both dynamic and static pile load tests are performed.

Two Dimensional Shear Wave Velocity Using the Inversion of Surface Waves (표면파 역산을 이용한 2차원 S파 속도구조에 관한 연구)

  • Jung, Hee-Ok
    • Journal of the Korean earth science society
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    • v.21 no.6
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    • pp.675-682
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    • 2000
  • 25 seismic shot gathers were obtained to study the two dimensional subsurface shear wave velocities in a landfilled area near the Keum river estuary. Borehole(BH#1 and BH#2) tests at two sites were made in the same area. Standard Penetration Tests were also performed at the same time. The 2-D shear wave velocity structure resulted from the inversion of the seismic data shows that the subsurface of the studied area consists of the upper 1${\sim}$3 meter thick layer(200 m/sec${\sim}$700 m/sec), the middle 5${\sim}$8 m thick low velocity layer(100 m/sec${\sim}$400 m/sec), and the lower layer of 1000m/sec or higher shear wave velocities. The thickness of the low velocity layer decreases from the BH #1 site to the BH #2 site. The depth to the basement also decreases toward the BH #2 site. The examination of the S wave velocity structure, the description of the geologic contents, and the Standard Penetration Test values indicate that the middle layer of low shear wave velocity may be related to the clay content of the layer. On the other hand, the Standard Penetration test values increase with depth, showing no significant relationship with the geologic contents of the subsurface. This study shows that the inversion of surface waves can be effective in the study of the shear wave velocity, especially in the area where low velocity layers can be found. The method of inversion of surface waves also can be used as a viable technique to overcome the limit of the seismic refraction method.

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A study on the estimation of undrained shear strength and preconsolidation pressure by N-Value (표준관입시험의 N값을 이용한 비배수전단강도 및 선행압밀응력의 추정)

  • Lee, Sung-Cheol;Kim, Ji-Yong;Jo, Sung-Min;Kim, Tae-Hyung
    • 기술발표회
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    • pp.303-310
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    • 2006
  • This study researched N-Value, strength of clayey soil and preconsolidation pressure m order to variety application of standard Penetration test. We compared it makes on analysis of the relationship of the N-value and $q_u$ with relation formula is presented in existing, presented the estimated preconsolidation pressure by using the predicted undrained shear strength.

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Driveability and Bearing Capacity Characteristics Analysis of 590 MPa Grade High Strength Steel Pipe Pile at Songdo Area through Dynamic Load Tests (동재하시험결과 분석을 통한 송도지역 590MPa급 고강도 강관말뚝의 항타관입성 및 지지력 특성 분석)

  • La, Seung-Min;Hong, Bong-Kyun;Yoo, Han-Kyu
    • Journal of the Korean Geotechnical Society
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    • v.27 no.2
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    • pp.81-90
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    • 2011
  • Domestic usage of high strength steel for pile has been limited to steel with yield strength (YS) of 490 MPa. However, design and construction cases abroad show beneficial usage of steel pipe with YS ranging in 500~700 MPa. In this study, YS 590 MPa steel pipe has been tested for driven pile foundation in Songdo area. Pile dynamic analysis (PDA) was carried out for 18 piles of which 16 piles have been reviewed for comparison of the PDA test results with those of GRLWeap analysis using SPT N value. Back analysis of PDA analysis was also carried out to narrow the deviation of standard SPT N value used in GRLWeap analysis. A regression equation is suggested for the shaft and toe resistance according to SPT N values for future GRLWeap analysis that can be used in the designing stage at Songdo area.

Analysis on Relation of S-wave Velocity and N Value for Stratums in Chungcheong Buk-do (충청지역 지층별 전단파속도와 N값의 상관관계 분석)

  • Do, Jongnam;Hwang, Piljae;Chung, Sungrae;Chun, Byungsik
    • Journal of the Korean Geoenvironmental Society
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    • v.12 no.10
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    • pp.13-22
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    • 2011
  • In this study, features of correlation between S-velocity and N value are derived from 9 suspension PS layers in Chungcheong Buk-do. S-velocity to be measured on Chungcheong Buk-do is classified into 5 as conditions of stratum that are ; cohesive soil layer, sandy soil layer, gravel layer, weathering soil layer, weathered rock layer. Each correlation formulas between N value by SPT and S-velocity is proposed from these classifications. And correlation formula for whole soil body except weathered rock layer also is proposed for reference. Corelation formulas developed this study formed square expression considering existing formulas produced internationally. Strength parameter converted to linear if N value is more than 50. Features of proposed formula which came up with comparative analysis of international result of cohesive soil layer and sandy soil layer and gravel layer show similar to existing ones. But there is deference that result of correlation formula for weathered rock layer is a little smaller than domestic formula's one. Because correlations of weathered rock layer above the N value of 50 is converted into a linear formation.

Determination of shear wave velocity profiles in soil deposit from seismic piezo-cone penetration test (탄성파 피에조콘 관입 시험을 통한 국내 퇴적 지반의 전단파 속도 결정)

  • Sun Chung Guk;Jung Gyungja;Jung Jong Hong;Kim Hong-Jong;Cho Sung-Min
    • 한국지구물리탐사학회:학술대회논문집
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    • pp.125-153
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    • 2005
  • It has been widely known that the seismic piezo-cone penetration test (SCPTU) is one of the most useful techniques for investigating the geotechnical characteristics including dynamic soil properties. As the practical applications in Korea, SCPTU was carried out at two sites in Busan and four sites in Incheon, which are mainly composed of alluvial or marine soil deposits. From the SCPTU waveform data obtained from the testing sites, the first arrival times of shear waves were and the corresponding time differences with depth were determined using the cross-over method, and the shear wave velocity profiles (VS) were derived based on the refracted ray path method based on Snell's law and similar to the trend of cone tip resistance (qt) profiles. In Incheon area, the testing depths of SCPTU were deeper than those of conventional down-hole seismic tests. Moreover, for the application of the conventional CPTU to earthquake engineering practices, the correlations between VS and CPTU data were deduced based on the SCPTU results. For the empirical evaluation of VS for all soils together with clays and sands which are classified unambiguously in this study by the soil behavior type classification Index (IC), the authors suggested the VS-CPTU data correlations expressed as a function of four parameters, qt, fs, $\sigma$, v0 and Bq, determined by multiple statistical regression modeling. Despite the incompatible strain levels of the down-hole seismic test during SCPTU and the conventional CPTU, it is shown that the VS-CPTU data correlations for all soils clays and sands suggested in this study is applicable to the preliminary estimation of VS for the Korean deposits and is more reliable than the previous correlations proposed by other researchers.

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A Study on the Evaluation of the Effect of the Ground Improvement of Reclaimed Land Based on Dynamic Compaction Method (동다짐 공법이 적용된 준설매립지반의 개량효과 평가에 관한 연구)

  • Kim Jong-Kook;Chae Young-Su
    • Journal of the Korean Geotechnical Society
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    • v.22 no.5
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    • pp.13-26
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    • 2006
  • The purpose of this study is to examine the method of liquifaction potential occuring at the reclaimed land in Incheon district and to compare the result obtained by the method based on the earthquake of 6.5 magnitude. In addition, the effects of ground improvement and liquifaction potential were evaluated on the basis of SPT and CPT, which have been performed before and after the compaction pilot test. As a result, we realized that the bigger the energy of dynamic compaction test was, the better effect we got. After the dynamic compaction test, as the strength of ground increased, the safe factor also increased. It was evaluated that the method of dynamic compaction improved the seismic performance. Accordingly, the method of the quality control of reclaimed land based on dynamic compaction method was presented.

Improvement Effects of Cement Grouting using Vibration Method through a Field Test (현장시험을 통한 시멘트 진동주입공법의 보강효과)

  • Han, Sanghyun;Yea, Geugweun;Kim, Hongyeon
    • Journal of the Korean Geoenvironmental Society
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    • v.15 no.5
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    • pp.23-29
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    • 2014
  • So far, the grouting using pressure injection has been extensively used to avoid adverse effects such as soil disturbance. Whereas, the pressure injection to the limitations of the diffusion range, so that the kinks would last injection of cement particles by introducing a frequency oscillation effect improved injection method have been recently developed. In this study, a pilot test was performed to compare injection effects of the both methods. The injections using both methods were tested on the embankment which consists of core clay and weathered soil. Subsequently, the injected volume, SPT N values, in-situ permeability and electrical resistivity were measured to compare their effects. The vibration method showed more effective permeation comparing with the pressure method. Also, it showed more homogeneously improved ground than the existing method. For SPT results, the vibration method presented increase of mean N value as much as 17.4 % comparing with the conventional method. Higher electrical resistivity was presented in case of injecting with vibration method and it indicated the injection was extensively completed. Finally, it is expected that the economic feasibility will be improved by decrease of drilling spacing, when the existing method is replaced with vibration method.