• Proceedings of the Korean Geotechical Society Conference
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• 2002.11a
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• pp.27-52
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• 2002

Pile driving formula, wave equation analysis of pile driving(WEAP) and dynamic pile loading test have been known to useful tools to appraise the behaviour of pile driving. This paper reviews basic theories of three methods and gives some suggestions to apply them to practice. And also some cases on application of the methods to the sites are discussed in this paper. It appears that it is inevitable for engineers to be experienced well so that the methods can be regarded as useful tools.

• Journal of the Korean Society of Safety
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• v.18 no.1
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• pp.81-88
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• 2003

Recently, pile foundations were constructed in rough or soft ground than ground of well condition thus it is important that prediction of ultimate bearing capacity and calculation of proper safety factor applied pile foundation design. This study were performed to dynamic loading tests for the thirty two piles at four different construction sites and selected pile at three site were performed to static loading tests and then compare with measured value and value of static and dynamic loading tests. The load-settlement curve form the dynamic loading tests by CAPWAP was very similar to the results obtained from the static load tests. Based on dynamic and static loading tests, the reliability of pile-driving formula were analyzed and then suggested with proper safety factor for prediction of allowable bearing capacity in this paper.

• Journal of the Korean Geotechnical Society
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• v.39 no.11
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• pp.71-84
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• 2023

In accordance with Korean structural foundation design standards, dynamic or static load tests are mandated for 1 to 3% of total piles. The construction quality of the remaining 97% to 99% of piles is determined through penetration measurements. This study aims to enhance the quality control of the majority of piles by adopting a pile driving formula that considers both penetration and hammer energy. The current challenge lies in adapting existing overseas driving formulas to the domestic site conditions, characterized by shallow weathered or soft rocks, and the prevalent use of pre-bored piles. To address this, the Modified Gates formula was refined using domestic dynamic load data, thereby improving its applicability to pile management. Despite employing fewer variables, the proposed formula demonstrates a comparable accuracy to dynamic loading tests in predicting the bearing capacity of pre-bored piles. Consequently, this formula holds promise for practical use in future pile quality management.

• Geomechanics and Engineering
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• v.9 no.3
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• pp.345-360
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• 2015

Wave equation analysis programs (WEAP) such as GRLWEAP and TNOWave were primarily developed for pre-driving analysis. They can also be used for post-driving measurement applications with some refinements. In the case of pre-driving analysis, the programs are used for the purpose of selecting the right equipment for a given ground condition and controlling stresses during pile driving processes. Recently, the program is increasingly used for the post-driving measurement application, where an assessment based on a variety of input parameters such as hammer, driving system and dynamic behaviour of soil is carried out. The process of this type of analysis is quite simple and it is performed by matching accurately known parameters, such as from CAPWAP analysis, to the parameters used in GRLWEAP analysis. The parameters that are refined in the typical analysis are pile stresses, hammer energy, capacity, damping and quakes. Matching of these known quantities by adjusting hammer, cushion and soil parameters in the wave equation program results in blow counts or sets and stresses for other hammer energies and capacities and cushion configuration. The result of this analysis is output on a Bearing Graph that establishes a relationship between ultimate capacity and net set per blow. A further application of this refinement method can be applied to the assessment of dynamic formulae, which are extensively used in pile capacity calculation during pile driving process. In this paper, WEAP analysis is carried out to establish the relationship between the ultimate capacities and sets using the various parameters and using this relationship to recalibrate the dynamic formula. The results of this analysis presented show that some of the shortcoming of the dynamic formula can be overcome and the results can be improved by the introduction of a correction factor.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03a
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• pp.51-63
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• 2000

Because of simplicity and easiness, dynamic pile driving formulae have long been used by most of the field engineers for pile quality control purposes. Yet their reliability have been repeatedly reported unsuitable and the results can lead to significant errors. According to the research results by the authors, the two most important sources of unreliability of dynamic pile driving formulae are uncertainty in the estimation of hammer efficiency and time dependent characteristics of pile bearing capacity. Based on this finding a new method is proposed. By using the actual value of hammer efficiency the pile bearing capacity at the time of driving could be reasonably estimated. By performing restrike test sometime after pile installation, time effect coefficient could be determined. The effectiveness of the proposed method was proven in the actual construction project.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.4
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• pp.23-30
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• 1985

Dynamic pile-driving formulas are widely used in predicting the load capacity of piles in cohesionless soils. However, the accuracy of the formulas has been questioned for a long time due to their oversimplified assumptions and empirical parameters involved in the formulas. The allowable pile capacities calculated by 6 different dynamic pile-driving formulas are compared statistically with the capacities measured in the field, in this paper, to find out the correlations between the calculated capacities and the measured values. The statistical data are then used to evaluate and to adjust the formulas to improve their accuracy. For the greatest accuracy and simplicity of use, it is recommended that the adjusted form of Gates formula be used. When the result of this recommended formula is compared with that of the existing Olson's modified formula, the former is found to be conservative by more than 10 percents.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.201-208
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• 1999

Pile driving technique has been regarded as the most reliable way of constructing deep foundations. Engineers have long believed that the quality of the installed piles is a simple function of the set values which can easily be obtained from the field pile driving records. Consequently most of the local building codes are based on the dynamic formula. However it has been proven that the quality of the driven pile is influenced not only by the set values but also by various factors, such as hammer performance, helmet characteristics, time dependent geotechnical characteristics of the site, etc., from the results of various researches made during the last two decades. In this paper an appropriate quality control scheme has been proposed by taking various influencing factors into consideration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.3 no.4
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• pp.133-142
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• 1983

A new dynamic pile-driving formula derived by the writer, in which the mechanics of stress waves and the effect of residual stresses were considered for more accurate prediction of the load carrying capacity of piles, was compared with other representative formulas through statistical analysis using the load test results. As the result, the new formula was estimated as highly accurate and reliable, with its safety factor less than 3.

• Journal of the Korean Geotechnical Society
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• v.17 no.5
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• pp.157-164
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• 2001

말뚝의 항타공식(또는 동적공식)은 간단하고 품질관리를 수행할 수 있는 실용적인 방법으로 이용되어 왔지만 신뢰도는 가정조건의 문제점으로 인해 매우 낮은 것으로 평가되고 있다. 실제적으로 동적공식은 항타시스템 및 항타과정 측면에서 보면 근본적으로 문제가 있는데, 그간의 많은 연구들은 이러한 사실을 고려하지 않은 상태에서 이루어 졌다. 본 연구에서는 동적공식의 문제점에 대해 평가해 보고 이를 바탕으로 새로운 동적공식을 제안하였다. 그리고 현장에서 항타분석기로 실측된 항타시 및 항타후 시험자료를 이용하여 새로운 동적공식의 신뢰도와 적용성을 평가하였으며 그 결과 새로운 동적공식의 실용성을 확인할 수 있었다.

• 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.