• Journal of the Korean Geotechnical Society
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• v.16 no.3
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• pp.119-129
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• 2000

국내에서 가장 많이 사용되는 현장조사방법인 표준관입시험의 결과로 얻어지는 N값에 대해 가장 큰 영향을 미치는 롯드 에너지 전단률(깽 Energy Ratio)을 지반조건이 상이한 3개 현장에서 항타분석기(Pile Driving Analyzer)를 이용하여 실측하였다. 에너지 전달률에 영향을 미치는 요인들 중엣 해머의 종류, 로프의 상태, 자아틀에 감은 횟수 등의 조건을 달리하여 롯드 에너지 전달률에 미치는 영향을 측정/분석하였다. 실험결과에 의하면 도넛해머, 안전해머, 개량형 도넛해머(Modified Automatic Donut Hammer)는 롯드에너지 전달률이 각각42%, 66%, 57% 정도로 측정되었으며 로프의 상태와 자아틀에 감은 횟수는 상대적으로 영향이 적은 것으로 측정되었다. 실험결과를 바탕으로 실측된 N값을 해머의 이론적 위치에너지의 60%에 해당하는 에너지가 롯드에 전달되었을 때의 N값(N60)으로 변환하기 위한 식을 제안하였다.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.618-622
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• 2007

In the past decades, complain about ground vibration and noise induced by pile driving has been quickly increased. Because of that, auger The role of train has expanded as mass transportation according to the increase of train passenger. The train operation personnel are more emphasis on the safety of train operation due to the increase of train's role. The reason is that the train transports many people daily. So, if there is natural disaster, such as earthquake, flood, high temperature, and so on, it will become disaster. Therefore, this paper introduces and proposes wayside detection system, which can be helpful for the safety assurance of train operation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.6
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• pp.453-460
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• 2002

In this paper, vibration criteria for fresh concrete are suggested considering relationship of strength and ages of concrete. Vibration criteria of fresh concrete subjected to construction vibration are not to be certain in abroad countries without question within a country. Before 12 hours cured, vibration criterion is suggested 0.25 cm/s. Used 4.0 cm/s by vibration criterion after 28 days. And the interval extent used relation with strength and ages of concrete. Vibration criteria proposed in this paper are thought may satisfy properties of fresh concrete as well as generally used those in domestic. Also, the actual ground vibrations due to pile driving have been measured, and data are analyze using the nitration equation applying to reliability index.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.469-476
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• 2001

The Ν-value in the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the doughnut hammer with the hydraulic lift system and the automatic trip hammer system were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA) . The rod energy ratio, ΕR$\_$r/ was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ΕR$\_$r/ also varies according to the energy instrumentation system and the analysis methods.

• Explosives and Blasting
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• v.33 no.2
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• pp.40-43
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• 2015

In this case study, a S/W optimized for ground vibration monitoring and analysis was developed. It was applied at vibrating compaction works for the ground improvement needed for the expansion of terminal 5 in Chagi International Airport in Singapore. The possible application of the new vibration analysis software to similar works like pile driving and the capability of long term and real time of the repeated wave vibration at seawalls, the vibration occurring from large structures like super tall buildings, tunnels, long cable hanging bridges, and etc were investigated.

• 기술발표회
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• s.2006
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• pp.75-85
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• 2006

The project comprised the construction of the new oil pier and associated topside facilities and demolition of exiting south pier. The site is located approximately 33km south of Kuwait city at MAA refinery. The approach trestle and berth structures of the new oil pier were designed to be supported by steel tubular piles Total 2,480 numbers of piles(795 piles at Approach Trestle, 1187 piles at Berth 1 -4 and 498 piles at Berth 5-6) had to be driven through the calcareous silty sand In this study, the design procedures for offshore steel pipe piles, evaluation for the compression and tension capacities by static and dynamic load test and effective driving criteria by the final set values are discussed

• 전기의세계
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• v.10
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• pp.29-37
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• 1963

일반적으로 이 함수의 측정은 원자로내에 Pile Oscillator봉이라고 칭하는 회전체를 넣어 이것에서 sinusoidal한 입력을 가할 수 있게 reactivity driving function을 얻는 것이 가장 중요한 역할을 하고 있는 관계로 이 봉의 회전속도변화(TRIGA MARK-II REACTOR 0.001-100cps, ARGONAUT REACTOR 0.01-20cps)를 매속 정확히 기록할 수 있어야 되는 것이다. 그러나 방사선으로 접근하기 어려운 원자로 근방에 있는 이 회전체의 속도측정은 원거리에서 취하여야 되는 고로 과거 사용하여온 110에서 25,000cpm을 측정할 수 있는 strobotac이나 100rpm에 대하여 2V을 발생시키는 tachometer등으로서는 어려운 문제가 되있는 것이다. 따라서 본연구에서는 이러한 점을 고려하여 binary switching circuit의 비선형적 특성의 해석과 이에 관계된 실험을 토시로한 pulse기술의 이용으로서 정밀도 0.0021에서 0.0043%를 갖는 정밀 회전속도측정기를 만들어 그 원리와 이용가치를 기술하고자 한다.

• Geomechanics and Engineering
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• v.4 no.1
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• pp.19-37
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• 2012

This paper presents the results of analytical and numerical analyses of the effects of performing a pressuremeter test or driving a pile in clay. The geometry of the problem has been simplified by the assumptions of plane strain and axial symmetry. Pressuremeter testing or installation of driven piles has been modelled as an undrained expansion of a cylindrical cavity. Stresses, pore water pressures, and deformations are found by assuming that the clay behaves like normally consolidated modified Cam clay. Closed-form solutions are obtained which allow the determination of the principal effective stresses and the strains around the cavity. The analysis which indicates that the intermediate principal stress at critical state is not equal to the mean of the other two principal stresses, except when the clay is initially isotropically consolidated, also permits finding the limit expansion and excess pore water pressures by means of the Almansi finite strain approach. Results are compared with published data which were determined using finite element and finite difference methods.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.03a
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• pp.71-78
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• 2002

The N-value from the standard penetration test(SPT) is affected by the magnitude of the rod penetration energy transmitted from the falling hammer as well as the geotechnical characteristics of the ground. Understanding of the striking energy efficiency in the SPT equipment is getting important for that reason. The energy efficiencies of the various type of equipment were investigated through field tests using the instrumented rod and wave-signal acquisition systems including the pile driving analyzer(PDA). The rod energy ratio, ERr was defined as the ratio of the energy delivered to the drilling rod to the potential free-fall energy of the hammer. It appears that the type of the hammer and lift/drop system had a strong influence on the energy transfer mechanism and ERr also varies according to the energy instrumentation system and the analysis methods.

• Journal of the Korean Geotechnical Society
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• v.16 no.1
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• pp.107-116
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• 2000

Dynamic and static load tests are conducted in four construction sites by using steel pipe piles(SPP) and concrete piles to compare differences of load bearing mechanism. Steel pipe piles are instrumented with electric strain gages and are subject to dynamic load tests during driving. The damage of strain gages attached is checked simultaneously. Static load test is also conducted on the same piles after two to seven days' elapse. Then load-settlement behavior and shaft and/or tip resistances are measured. As a result, the allowable bearing capacity calculated by the Davisson's offset method of CAPWAP analysis shows 2~33% larger than that of static load test. The average value of allowable bearing capacity of static load test is closer to the allowable capacity obtained at the safety factor of 2.5 applied on ultimate bearing capacity than to the one obtained from the Davisson's offset method. The analysis of strain gage readings shows that unit skin friction increases with depth. Furthermore, the friction mobilized around the 1~2m above the pile tip considerably contributes to the total shaft resistance.