• Geotechnical Engineering
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• v.12 no.5
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• pp.117-126
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• 1996

In spite of many advantages such as the simplicity in test procedure, Standard Penetration Test(SPT) results contain some errors caused by the variability of test equipment, instruments and test procedures. Especially, it is inevitable that the measured SPT hammer energy is different from the theoretical value because of energy loss. In this paper, the hammer energy level is measured during the performance of the field SPT in Korea by using a ultra-sonic system and PC.program. As the results of this study, the average hammer energy ratio of the R-P hammer and the Trip hammer is calculated at 64.2%, and at 75.0% respectively. The average energy ratio of the SPT for the R-P hammer is calculated at 46% and at 54% for the Trip hammer, by applying the rod energy ratio 0.72.

• Journal of the Korean Geosynthetics Society
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• v.11 no.4
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• pp.45-53
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• 2012

Ground drilling is a common method to conduct site investigation, soil improvement, and pile installation. In the point of construction ground drilling requires electrical energy to drill a hole in ground in which the energy exerts into the motor located on the head of auger and generates rotational power. In this paper it is verified that the exerted electrical energy is closely related to the strength characteristics of ground. Measurement sensors, recording system, and drilling system were developed to obtain exerted motor current and drilling depth and laboratory soil box tests were carried out. The measured motor current and boring depth were applied to predict SPT N-value and the prediction results were compared to SPT N-value of laboratory tests. The test results show that the exerted electrical energy to bore ground be a good index to estimate SPT N-value.

• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.5-11
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• 2023

Economic damage is occurring due to landslides and debris flows that occur when the ground artificially created for roads or photovoltaic power generation facilities is weakened by rainfall such as torrential rain. In order to understand the stability of the artificially created ground, it is very important to check the ground information such as the compositional state and mechanical characteristics of the stratum. However, since most of the investigation sites are steep slopes or there are no access roads, it is not easy to enter the drilling equipment commonly used to check ground information and perform standard penetration tests. In this study, a dynamic cone penetration test (DCP) device using a miniaturized auger drilling equipment and an automatic drop device was developed to check the cone resistance value and the dynamic cone penetration test value and analyze the correlation with the standard penetration test value to confirm its applicability at the mountain solar power generation site. As a result, the cone resistance value is q_d = 0.46 N and the dynamic cone penetration test value is N_d = 1.58 N, confirming a value similar to the results of existing researchers to secure its reliability.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.6
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• pp.2359-2368
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• 2013

Cone penetration tests (CPTs) have been increasingly used for site characterizations. However, the site investigations using CPTs are often limited due to soil conditions depending on the cone size and capacity of the CPT system. The small sectional area of a miniature cone improves the applicability of the CPT system due to the increased capacity of the CPT system. A continuous intrusion system using a coiled rod allows fast and cost effective site investigation. In this study, the performance of the continuous intrusion miniature cone penetration test (CIMCPT) system has been evaluated by comparison tests with the standard CPT system at several construction sites in Korea. The results show that the CIMCPT system has a same performance with the CPT system and has advantages on the mobility and applicability. According to field verification tests for scale effect evaluation, the cone tip resistance evaluated by CIMCPT overestimates by 10% comparing to standard CPTs. A crawler mounted with the CIMCPT system has been implemented to improve accessibility to soft ground, and has shown improvement over the truck type CIMCPT system. Therefore, the improved CIMCPT system can be utilized as a cost effective and highly reliable soil investigation methodology to detect the depth of soft ground and to evaluate soil classification.

• The Journal of Engineering Geology
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• v.26 no.4
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• pp.497-503
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• 2016

The cement grouting by vibration method (CGVM), a new construction technology developed in Korea, aims to efficiently reinforce a target ground area by injecting vibrated grout into it. The present study applies the CGVM to test sites and verifies its effect. Standard penetration tests (SPTs), field permeability tests, and geophysical surveys were conducted in two study areas, and the results were compared between before and after CGVM application. The SPT conducted before and after the CGVM application showed that the N value was increased by 33.57% point to 60.90% point. The field permeability test showed that the permeability coefficient decreased. These results indicate that CGVM may increase imperviousness and improve reservoir system stability. In addition, a resistivity survey found no low-resistivity zone, unlike before the CGVM application, thereby indicating the excellent grouting effect of the CGVM.

• Geotechnical Engineering
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• v.13 no.1
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• pp.169-182
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• 1997

It is known that some amount of loss in impact energy takes place due to some limitations and problems during the performance of the field SPT. Actual energy level tractsferred to the rod should be measured to correct the SPT-N values tested in the field In this paper, the ratio of energy transferred to the rod through the anvil to impact energy is measured by using sharpy impact test equipment and also analysed by using GRL-WEAP This result is certified and compared with that of field SPT As the results of this study, the average rod energy ratio of the R-P hammer and the Trip hammer is calculated at 0.726 and 0.728 respectively, but it is suggested that 0.72 should be used. By using the hammer energy ratio 64.2% and 75.0% obtained from field measurement, the average energy ratio of the SPT for the R-P hammer is calculated at 46.7% and 54.5% for the Trip hammer.

• 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.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1425-1434
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• 2009

This study was aimed at comparing and assessing SPT-N values both measured by automatic and manual record devices of Standard Penetration Test. As a result, energy efficiency of hammer was approximately 62.9%, meaning SPT-N value measured by automatic recording device showed relatively accurate performance that the one done by manual device. Given the relations between hit frequency of automatic recording device and intrusion, the characteristics of stratum are expected to be proved in more accurate way. Additionally, higher confidence level seems to make it preferred and quality assessment method.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.3
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• pp.1778-1785
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• 2014

In order to construct offshore structures safely, geotechnical investigation should be carried out with high accuracy. Up to now, onshore geotechnical investigation equipments installed on the barge are used for offshore geotechnical investigation. In this case, many limitations can be confronted such as deep water depth, high wave, strong current, severe wind and so on. For the safe and economic offshore geotechnical investigation with high precision, a seabed type unmanned automated site investigation equipment is developed. It can be operated remotely underwater conditions with 100m water depth and can explore the ground depth of 50m. Also, the standard penetration test (SPT), soil boring, soil sampling and rock coring can be possible using the equipment. Numerical analysis was conducted to secure the stability of the equipment against current of 4 knot. Energy efficiency of SPT apparatus which is attached to the equipment shows 78% in average.

• Journal of the Korean Geotechnical Society
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• v.19 no.3
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• pp.23-31
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• 2003

Over the past half century, borehole seismic surveys have been diversified into the three techniques such as crosshole, downhole, and suspension logging according to their devices and testing configurations. These field techniques have been improved, in terms of equipment and testing procedures, and are very valuable in the evaluation of ground characteristics for geotechnical and earthquake engineering problems. Yet, despite the importance and significance of the techniques as engineering tools, the techniques are not much used as standard penetration test (SPT) by practicing engineers. The possible explanations are cost and operational difficulties of the surveys as well as sophistication and complexity of the devices. An in-hole seismic method has been developed to meet the requirement of economical testing cost and practicality in engineering practice to measure dynamic soil properties. The prototype in-hole probe developed herein is small and light enough to be fit in three-inch boreholes and to be handled with bare hands. The performance of the source has been evaluated through extensive crosshole tests at various sites. The in-hole seismic method was adopted at three test sites and verified by comparing with crosshole results.