• Journal of the Korean GEO-environmental Society
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• v.20 no.2
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• pp.59-67
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• 2019

Using the results from laboratory soil test, field vane test and piezocone penetration test, the engineering characteristics of the soft ground at east side of Gwangyang Port, which is located at south coast of Jeollanam-do, were investigated and optimal piezocone penetration test depth was derived to calculate piezocone factor. In this paper, the results of 61 laboratory soil tests, 226 times of field vane tests and 26 piezocone penetration tests were used. The result of laboratory soil test suggested that some physical properties such as specific gravity, moisture content, liquid limit and plastic index and others are higher than other south coast regions, meanwhile uniaxial compression strength, undrained shear strength, defined as mechanical property, appeared to be relatively small, distributed widely. According to the plastic chart, the ground was classified as high compressibility clay and low compressibility clay, mostly represent to Type 3 clay by Robertson (1990)'s classification chart. Piezocone factor was calculated by empirical method, based on the undrained shear strength which was obtained by the field vane test. According to the analysis with 3 different depth range, to set the appropriate measured depth range of piezocone penetration for comparation, using average value of the range of 5 times the vane length showed the highest correlation.

• Journal of the Korean GEO-environmental Society
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• v.7 no.5
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• pp.13-20
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• 2006

We have conducted standard penetration tests and static cone penetration tests that are widely used the land base examination on the soft ground subsurface of Yongdong area, and examined the correlation between them. We have also made a comparative analysis of the correlation between the indoor tests on the materials collected on the site and on-the-spot penetration tests. The results are as follows : The relationship between Standard Penetration Test N-value and Dutch Cone Tset show $Q_c=1.93N+0.29$ for organic soil, $Q_c=2.19N+0.20$ for clay, $Q_c=2.34N+1.06$ for silt, $Q_c=3.02N+0.54$ for silty sand, and $Q_c=3.47N+0.46$ for sand. In this case of sand $Q_c/N$ increases when the soil particles are larger. The relationship between standard penetration test N-value and Unconfined Compression Strength $q_u$ show $q_u=0.11N+0.03$ for organic soil, $q_u=0.11N+0.25$ for clay, and $q_u=0.18N-0.03$ for silt.

• Journal of the Korean Geotechnical Society
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• v.38 no.11
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• pp.97-106
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• 2022

The domestic auger-drilled pile method generally manages the driving penetration (set) value with the final stage of construction. The penetration value has been estimated by manual measurement for a long time. The automation technology is yet to be applied due to workability and high-cost limitations, despite safety issues and lack of reliability in measured results. In this study, a non-contact pile penetration measurement device was developed. Further, the field performance was verified by comparing the measurements with a conventional automation device. In addition, the on-site field quality control method was analyzed using the penetration measuring device. The field experiments confirmed that more reliable bearing capacity estimation could calculate the dynamic damping coefficient and the modified Hiley formula with the developed device. Furthermore, it can be used for pile construction management from the bearing capacity viewpoint, even for piles not subjected to dynamic load tests. 

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5572-5577
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• 2012

Results of in-situ test, laboratory test and strength prediction method for the soft soil underlain by failed road embankment were compared each other. Comparing cone penetration test results with the field vane test results it can be seen that cone factor is 12. Undrained shear strengths determined from the cone factor which was predicted by prediction equation were smaller than those obtained from field vane tests. Among the prediction methods Jamiolkowsky's method gave close strengths to the measured undrained shear strengths by field vane tests and strength ratio were 0.88~1.23.

• International Journal of Highway Engineering
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• v.6 no.3 s.21
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• pp.17-26
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• 2004

The in-situ California Bearing Ratio (CBR) test has been widely used for evaluating the subgrade condition in asphalt concrete pavements. However, because the in-situ CBR test is expensive and takes plenty of time for operation, it is very difficult to figure out the in-situ characteristics of subgrade strength in detail. For faster and economical operation, the Dynamic Cone Penetrometer (DCP) has been often utilized for estimating the subgrade strength in the field. The relationship between the CBR value and DCP index obtained from the DCP testing has been studied using the laboratory and in-situ testing by other foreign researchers. The objective of this study is to determine the relationship between in-situ CBR value and DCP index of the subgrade materials used in Korea. The DCP index for evaluating the strength of subgrade materials produced in Korea is presented in this paper. Research results propose the regression equation to explain the relationship between the CBR and DCP tests. The in-situ CBR values of subgrade materials range from 20 to 45% indicating the good and sound subgrade condition.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.135-146
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• 2003

Uphole test is a seismic field test using receivers on ground surface and a source in depth. In this paper, the uphole test using SPT(standard penetration test) which is economical and reliable for obtaining shear wave velocity profile was introduced. In the proposed uphole test, SPT sampler which is common in site investigation, was used as a source and several 1Hz geophones in line were used as receivers. Test procedures in field and interpretation methods for obtaining interval times and for determining shear wave velocity profile considering refracted ray path were introduced. Finally, uphole test was performed at three sites, and the applicability of the proposed uphole test was verified by comparing wave velocity profiles determined by the uphole test with the profiles determined by downhole test, SASW test and SPT-N values.

• Journal of the Korean Geotechnical Society
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• v.23 no.12
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• pp.53-60
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• 2007

A program for predicting rate of penetration of sheet pile using cone penetration test results was developed. Especially, energy consumption occurring from lateral vibration of sheet pile was estimated quantitatively in order to overcome overprediction of rate of penetration for shallow depths of pile installation. Penetration rates of pile calculated from developed program were compared with those of field test. Predicted rates of pile penetration for the depths to 12m were $47%{\sim}120%$ of the measured values. As pile penetration depth decreases, the difference between the predicted rate of penetration and the measured rate of penetration decreases.

• International Journal of Highway Engineering
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• v.14 no.3
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• pp.49-58
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• 2012

In many countries including Korea, the design concept of pavement structure has been converted from empirical method to mechanisticempirical method since the advent of compaction control based on resilient modulus proposed by AASHTO in 1986. Studies of last decades indicates that the classical compaction control method based on relative compaction and plate bearing test(PBT) will necessarily move to the methods taking advantage of light falling weight deflectometer(LFWD) and dynamic cone penetrometer(DCP) in addition to PBT. In this study, the validity of resilient modulus prediction equation proposed by Korean Pavement Design Guide is verified by comparison with physical properties of subgrade soil and the results of structural analysis. In addition, correlational equations between elastic modulus measured by various field tests and resilient modulus estimated by empirical model are proposed. Finally, a field test-based compaction control procedure for subgrade is suggested by using proposed correlational equations.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.153-160
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• 2001

피에조콘관입시험(PCPT)의 소산시험은 in-situ 상태의 압밀계수(c/sub v/)를 추정하는 방법으로 널리 이용되어왔다. 본 연구에서는 spherical cavity expansion theory 및 axisymmetric uncoupled linear consolidation equation(Gupta & Davidson, 1986)을 이용하여 과압밀점토에서의 초기과잉간극수압의 분포 및 과잉간극수압의 시간에 대한 소산현상을 해석하는 수치해석방법을 제안하여 현장시험결과 및 실내시험결과와 비교 분석하였다. ADIS (alternating direction implicit scheme)를 이용한 FDM 해석을 실시한 결과와 현장시험의 소산곡선은 잘 부합되는 것으로 나타났으며 압밀계수도 실내실험 또는 피에조콘관입 시험에 대한 추정방법으로 산출된 값과 비교적 일치하는 것으로 나타났다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5C
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• pp.313-320
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• 2008

The discharge capacity testing apparatus using penetration method, being able to simulate in laboratory the condition of embedding plastic board drains in field, was developed to investigate consolidation characteristics of ground and to figure out discharge capacity of drains. The developed apparatus with a mandrel and penetrating device was designed to insert PBD into the ground prepared by previously applied pressure, being different from the conventional testing method that the drain was installed and the ground material was poured subsequently. Discharge capacity tests with the conventional apparatus as well as the newly developed one were performed to assess the applicability of the latter. As a result of tests, the conventional method showed delayed consolidation due to overall disturbance of ground and local deformation of drain caused by inhomogeneity of ground. Therefore discharge capacity of drain with the conventional apparatus was measured more or less larger than the expected values whereas discharge capacity with new one could be measured similar to the actual value in field.