• Title, Summary, Keyword: 동적콘관입시험

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Prediction of End Bearing Capacity for Pre-Bored Steel Pipe Piles Using Instrumented Spt Rods (SPT 에너지효율 측정 롯드를 이용한 매입말뚝의 선단지지력 예측)

  • Nam, Moon S.;Park, Young-Ho;Park, Yong-Seok
    • Journal of the Korean Geotechnical Society
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    • v.29 no.12
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    • pp.105-111
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    • 2013
  • The standard penetration test (SPT) has been widely used because of its usability, economy, and many correlations with soil properties among other factors. In SPT, hammer energy is an important factor to evaluate and calibrate N values. To measure hammer energy, an instrumented SPT rod was developed considering that stress waves transferring on rods during SPT driving are the same as stress waves transferring on piles due to pile driving. Using this idea, an instrumented SPT rod with a pile driving analyzer was applied as a pile capacity prediction tool in this study. In order to evaluate this method, SPT and dynamic cone tests with the instrumented SPT rod were conducted and also 2 pile load tests were performed on pre-bored steel pipe piles at the same test site. End bearings were predicted by CAPWAP analysis on force and velocity waves from dynamic cone penetration tests and SPT. Comparing these predicted end bearings with static pile load tests, a new prediction method of the end bearing capacity using the instrumented SPT rod was proposed.

Development and Application of Cone Penetrometer with Impact Penetration Rod for Evaluation of Track Substructure (철도궤도 하부구조물 평가를 위한 타격식 관입 롯드가 체결된 콘 관입기의 개발 및 적용)

  • Hong, Wontaek;Byun, Yonghoon;Kim, Sangyeob;Choi, Chanyong;Lee, Jongsub
    • Journal of the Korean GEO-environmental Society
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    • v.16 no.2
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    • pp.45-52
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    • 2015
  • To minimize the cost of maintenance, repair and over-design of track substructure, an accurate evaluation of strength and stiffness of the track substructure is necessary. In this study, a cone penetrometer with impact penetration rod (CPI) is developed for the evaluation of track substructure. For applicability test, the chamber and field tests were performed. As the experimental results of the CPI, dynamic cone penetration endex (DCPI), cone tip resistance ($q_c$), friction resistance ($f_s$) and friction ratio (Fr) were obtained. In the chamber test, the experimental results show reasonable values for the simulated track substructure. In the field test, the CPI clearly detects the interface between the ballast and the subgrade. Also, discontinuous layers are detected in the subgrade. It is expected that the developed CPI may be an effective tool for the evaluation of track substructure by evaluating the ballast layer by dynamic penetration and the subgrade by static penetration of the inner rod.

Comparison of Elastic Moduli of Subgrade Soils Using Plate Loading Test, Soil Stiffness Gauge and Dynamic Cone Penetrometer (평판재하시험, 흙강성측정기 및 동적콘관입시험기를 이용한 노상토의 탄성계수 비교)

  • Kim, Kyu-Sun
    • Journal of the Korean Geotechnical Society
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    • v.31 no.3
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    • pp.63-72
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    • 2015
  • This paper describes the correlation and relationship between elastic moduli measured by three stiffness measurement methods with different mechanical characteristics to evaluate the compaction characteristics of subgrade soils. The Soil Stiffness Gauge (SSG) with very small strain (${\approx}0.001%$) ranges, static Plate Loading Test (PLT) with mid-level strain (${\approx}0.01{\sim}0.1%$) ranges, and Dynamic Cone Penetrometer (DCP) using penetration resistance were implemented to measure the elastic modulus. To use the elastic modulus measured by different measurement methods with a wide range of strain in practice, it is required to identify the correlation and relationship of measured values in advance. The comparison results of the measured elastic moduli ($E_{SSG}$, $E_{PLT}$, $E_{DCP}$) using the three measurement methods for domestic and overseas subgrade soils under various conditions indicate that the evaluated elastic modulus relies on the types of soils and the level of stress condition. The correlation analysis of the measured elastic moduli except the data of cement treated soils indicates that the static elastic modulus ($E_{PLT}$) is evaluated as about 60 to 80% of the dynamic elastic modulus ($E_{SSG}$). Unusual soils such as cement treated soils are required to be corrected by the stress correction during the correlation analysis with typical soils, because these types of soils are sensitive to the stress condition when measuring the static elastic modulus ($E_{PLT}$) of soils. In addition, when considering the use of DCP data for the evaluation of the elastic modulus ($E_{DCP}$), the measured data of the elastic modulus less than 200 MPa show more reliable correlation.

The Ground Investigation Technique of Railway Using Pagani Cone Test (Pagani Cone Test를 이용한 철도노반 조사 기법 연구)

  • Cho, Eun-Kyung;Cho, Kook-Hwan
    • Journal of the Korean Society for Railway
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    • v.19 no.6
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    • pp.792-801
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    • 2016
  • Standard Penetration Test (SPT) and Cone Penetration Test (CPT) are widely used in geotechnical investigation methods for railway roadbed. However, SPT can not be used on the Railway track, since the equipment may contact to the electric lines. However, a portable equipment can be used for geotechnical investigation without electrical hazard. Dynamic Cone Penetrometer (DCP) is one of representative portable equipments. A normal portable DCP has usually not enough driving energy and the rigidity of cone-rod, so it is impossible to investigate the required investigate penetration depth. In this study, The adaptability of Pagani cone test which is one of portable dynamic cone penetrometer is studied and compared with SPT-N data. As a result of this study, the proposed correlation factors between Pagani cone test and SPT-N values after corrections is 1.48 for sandy soil and 1.33 for clayey soil.

A Pilot Study of Inhole Type CPTu from Model Tests (실내모형실험을 통한 인홀형 탄성파콘 시험의 적용성 분석)

  • Jang, In-Sung;Jung, Min-Jae;Kwon, O-Soon;Mok, Young-Jin
    • Journal of The Korean Society of Civil Engineers
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    • v.28 no.2C
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    • pp.95-103
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    • 2008
  • Seismic piezocone penetration tests (SCPTu) can be used to obtain dynamic properties of soils as well as cone resistance and penetration pore pressure. However, the SCPTu system can be hardly utilized in marine soils because it is difficult to install the source apparatus which generates the shear wave in offshore site. The authors developed an inhole type piezocone penetration test (CPTu) equipment which both source and receiver composed of bender elements were installed inside the rod located behind the cone. Therefore, it can be applicable to even an offshore site without any additional source apparatus. The objective of this paper is to investigate the practical application of inhole type CPTu by performing laboratory model tests using kaolinite as soft clay. The shear wave velocities of kaolinite soil were measured with time, and the effects of soil disturbance due to the installation of source and receiver were also examined for various distance between source and receiver.

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Curing Characteristics of Controlled Low Strength Material Made with Coal Ashes (석탄회를 사용한 저강도 고유동화재의 경화 특성 분석)

  • Kim, Juhyong;Cho, Samdeok;Kong, Jinyoung;Jung, Hyuksang;Chun, Byungsik
    • Journal of the Korean GEO-environmental Society
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    • v.11 no.11
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    • pp.77-85
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    • 2010
  • Unconfined compressive strength tests were performed to evaluate curing characteristics of controlled low strength material(CLSM) made with coal ashes. It is found that unconfined compressive strength normalized by curing times, increases as decreasing the water contents of CLSM particularly during first three days. Dynamic cone penetrometer tests were also carried out to evaluate cost-effective CLSM lump strength characteristics with time. It takes around 10 days to reach target strength, 500kPa (penetration rate, 20mm/blow). Curing rate significantly decreases after 10 days elapsed regardless of CLSM formulation.

Stiffness Characterization of Subgrade using Crosshole-Type Dynamic Cone Penetrometer (크로스홀 형태의 동적 콘 관입기를 이용한 노반의 강성특성 평가)

  • Hong, Won-Taek;Choi, Chan Yong;Lim, Yujin;Lee, Jong-Sub
    • Journal of the Korean Geotechnical Society
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    • v.34 no.2
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    • pp.55-63
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    • 2018
  • In order to support the load of the train with enough stiffness, a study on an effective method for the characterization of the stiffness of the compacted subgrade is required. In this study, the crosshole-type dynamic cone penetrometer (CDCP) is used for the stiffness characterization of the subgrade along the depth. For the application of the CDCP test, three points of compacted subgrades are selected as the study sites. For the study sites, CDCP test, in-situ density test, and light falling weight deflectometer (LFWD) test are conducted. As the results of CDCP tests, shear wave velocity profiles are obtained by using the travel times and the travel distances of the shear waves along the depth. In addition, maximum shear modulus ($G_{max}$) profiles are estimated by using the density of the subgrades and the shear wave velocity profiles. The averaged maximum shear moduli at each testing point are highly correlated with the dynamic deflection moduli ($E_{vd}$) determined by LFWD tests. Therefore, a reliable stiffness characterization of the subgrade can be conducted by using CDCP tests. In addition, because CDCP characterizes the stiffness of the subgrade along the depth rather than a representative value, CDCP test may be effectively used for the stiffness characterization of the subgrade.

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.

Model Tests for the Applicability of various Testing Devices for Measuring Degree of Compaction (여러 가지 다짐평가 장비의 적용성에 대한 모형 시험)

  • Back, In-Chul;Yoo, Wan-Kyu;Kim, Byoung-Il;Kim, Ju-Hyong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.8 no.5
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    • pp.1152-1158
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    • 2007
  • Although various fast and simple, testing devices have been developed in many countries such as the U.S, Japan, and European countries, these testing devices are not commonly used in Korea. In this study, compaction fur the field density test was carried out with a hand-guided vibrating roller. The results of the field density test were compared with those of the new testing devices such as the geogauge, soil impact hammer(CASPFOL), light falling weight deflectometer(LFWD), dynamic cone penetration(DCP). Regression analyses were conducted with the data from new testing devices. The analysis results showed that the correlation coefficients were high in the range of $70{\sim}95%$.

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Assessment of Shear Strength Parameter for Weathered Soils Using Artificial Neural Network (인공신경망을 이용한 풍화토의 강도정수 산정)

  • Lee, Moo-Cheol;Lee, Song
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.3
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    • pp.147-154
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    • 2008
  • Weathered soil slope loses its shear strength if it is exposed in the air for a long time or in contact with water. And this kind of strength loss is remarkable in dam slope which has very big difference in water level according to the season. In this study, shear strength loss of weathered soil due to saturation had been found out through dryness and wetness repetition direct shear test. Also relation between penetration blow number(Nc) and shear strength parameter had been found out through small sized dynamic cone penetration test device and the correlation equation of Nc had been proposed through artificial neural network analysis to estimate shear strength parameter easily.