• Geotechnical Engineering
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• v.3 no.4
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• pp.31-40
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• 1987

A helical probe test (HPT) suitable for in.situ soil exploration to a shallow depth and compaction control were developed and tested in different soils alongside traditional in-situ tests, including Standard Penetration Test (SPT), Cone Penetration Test (CPT) and in-situ density test. The helical probe test is economical and can be performed by a single person. The torque necessary to insert the probe Is used as a measure of soil characteristics. It was found that: the HPT test correlates well with the SPT test and the correlation is not sensitive to the soil type; the HPT test correlates well with the CPT test, but the correlation is sensitive to the soil type; the HPT torque provides a sensitive measure of relative compaction rind in-situ dry density of compacted soils; the reverse torque ratio decreases with increasing average grain sloe.

• The Journal of Engineering Geology
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• v.8 no.1
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• pp.25-34
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• 1998

It is not easy to understand exact soil properties, because soil is nonhomogeneous and anisotropic. There are raany inefficient cases in aspect of time and economy in site survey. So this study tried to analyze the correlation of cone resistance and seismic velocity in order to present an efficient method in ground investigation. A cone penetrometer is frequently used to investigate soil properties, which are especially fit to investigate coastal soft ground. A portable cone penetrometer was used in this research. A portable cone penetrometer has an advantage in investigating the state of soil swiftly and is convenient to manipulate. Also, seismic prospecting is one of the most PoPular methods among geophysical prospecting methods in the estimation of ground properties and its usage is continuously increasing in the survey of soft ground Cone resistance makes a regular group according to stratum in each depth. The results of seismic prospecting show a tendency to have a certain coherence according to the boundary of straturft Therefore, cone resistance and seisrnic prospecting have considerable relations that rnay irnprnve the efficiency of ground investigation.

• The Journal of the Petrological Society of Korea
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• v.7 no.3
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• pp.161-176
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• 1998

There are exposed Samrangjin Tuff and intracaldera intrusions, of which rhyolitic rocks emplaced as postcollapsed central and ring intrusions within the Samrangjin caldera, and fine-grained granodiorite and biotite granite as regional tectonic intrusions nearby. The Samrangjin Tuff and the rhyolitic rocks are of a single Samrangjin magmatic system. Flow-banded rhyolite among rhyolitic rocks was emplaced in the outer part of the ring intrusions, rhyodacite in the inner part of the eastern ring, and porphyritic dacite and dacite porphyry in the inner part of the northwestern ring. Totally the Samrangjin Tuff and the rhyolitic rocks range from rhyolite to dacite in chemical composition. The Rb-Sr isotopic data of the Samrangjin Tuff and the rhyolitic rocks yield an age of $80.8{\pm}1.5(2{\sigma})$ Ma with the initial $^{87}Sr/^{86}Sr$ ratio of $0.70521{\pm}0.00010(2{\sigma})$. The continuous compositional zonations generally define a large stratified magma system in the postcollapse magma chamber. The Sr isotopic data suggest that the compositional zonations might have resulted from the fractional crystallization of a parental dacitic magma.

• 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 Recycled Construction Resources Institute
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• v.7 no.4
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• pp.358-366
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• 2019

The purpose of this study is to explore the possibility of estimating optimum surface finishing work time of the fresh concrete placed at the job site by applying a surface hardness test meter(Durometer). Tests are carried out by measuring and comparing the Proctor penetration resistance test and hardness test by Durometer. Correlations between Procter penetration test and hardness test by Durometer were obtained. Two different types Durometer were applied to estimate setting time. Test results indicate that the measurement of the Durometer and the test of the Proctor penetration resistance are highly correlated. When measuring the initial setting time with Durometer, initial setting time is reached when the hardness value by the type C Durometer is reached around 42HD, and when final setting is measured with the type D Durometer, the surface finishing work time limit and curing time can be estimated with 10HD of Durometer.

• The Journal of the Petrological Society of Korea
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• v.1 no.2
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• pp.132-137
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• 1992

Review of metamorphic terms and rock names from various published articles in Korea reveals that they have often been misused and they may lead to a faulty results in the interpretations of the geologic mass. Their usage can be classified into several groups. A few simple rules are proposed for use in naming metamorphic rocks. The new rock names make by the proposed rules are listed as table with old names.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.2C
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• pp.83-94
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• 2008

In this study an effective stress analysis was performed to evaluate liquefaction potential and ground settlement for reclaimed sites. The effective stress model can simulate the stiffness degradation due to excess pore pressure and resulting ground deformation. It is applicable to a wide range of strain. An equivalent linear analysis suitable for low strain levels was also carried out to compare the effective stress analysis. Shear stress ratio calculated from an equivalent linear analysis was used to determine SPT blow count to prevent liquefaction. Depending on the magnitude of potential earthquake and fine contents, the SPT blow count was converted into an equivalent cone tip resistance. It was compared with the measured cone tip resistance. The measured elastic shear wave velocity and cone tip resistance from two reclaimed sites in Incheon were used to perform liquefaction analyses. Two liquefaction evaluation methods showed similar liquefaction potential which was evaluated continuously. The predicted excess pore pressure ratio of upper 20 m was between 40% and 70%. The calculated post-shaking settlement caused by excess pore pressure dissipation was less than 10 cm.

• Journal of the Korean Geosynthetics Society
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• v.10 no.4
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• pp.61-70
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• 2011

This paper describes prediction results of penetration rate using case history in order to compare empirical models for penetration rate prediction of TBM. The reasonable empirical model is evaluated by comparison with prediction results and measured result. The penetration rate prediction is applied in separate empirical models considering rock characteristics and mechanical characteristics of TBM. The rock of applied filed had almost gneiss and its unconfined compressive strength was irregular due to the exist of weak zones and joint. In prediction results using unconfined compressive strength, Graham's model (1976) had impractical result when it had lower strength. NTNU model (1998) of the separate empirical models used in average penetration rate had the highest accuracy by comparison with the others, because it is a reasonable model which has rock characteristics and mechanical characteristics of TBM. However, Tarkoy's model (1986) based on unconfined compressive strength correspond with the measured values in field. Therefore, it should be considered a rock type, geological characteristic and mechanical characteristic of TBM at prediction of penetration rate.

• 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.

• Journal of the Korean GEO-environmental Society
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• v.6 no.3
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• pp.25-34
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• 2005

The governing design point of shallow foundation is not its bearing capacity but its settlemen and N-value by the SPT is one of the key parameters for settlement estimation. However, if the N-value is more than 50/30, such as 50/10 or 50/20, the N-vlaues are not blow count of 30cm depth penetration. In these cases, the estimated settlements have big difference with the measured values because the applied maximum N value for the settlement estimation is 50. Therefore, in this study, the modified method for N-value estimation is suggested. The settlements by four methods, which are based on Elastic Theory with application of modified N-value, are compared with the Origina Plate Load Test data. The same comparision was carried out with another seven Empirical Methods. The result of this study showed that the error range of settlement is decreased from 260.4~2136.5% to 20.3~272.7%. Among four methods which are based on Elastic Theory, the original method by Elastic Theory is the most accurate with the application of modified N-value. Among Empirical Methods, Terzaghi-Peck's(1948, 1967) modified method 1 is the most accurate with the application of modified N-value. The differences between the original method by Elastic Theory and Terzaghi-Peck's(1948, 1967) modified method 1 are neglectable.