• Title/Summary/Keyword: hammer

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A Propoal for an Appropriate Quality Control of Driven Piles (합리적인 항타시공 관리방안)

  • 이명환;홍헌성;조천환
    • 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.

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Estimation of Compressive Strength of Concrete with Granitic Aggregates : Rebound hammer and Ultrasonic Methods (화강암 골재를 사용한 콘크리트의 비파괴 시험에 의한 강도평가)

  • 김현우;이종태;윤기원;김병극;김무한;한천구
    • Proceedings of the Korea Concrete Institute Conference
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    • 1999.10a
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    • pp.651-654
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    • 1999

  • It is required that the compressive strength of concrete should be estimated accurately from the view point of efficient quality control and maintenance of buildings. In this paper, the equations to estimate the compressive strength of concrete using granite aggregates were suggested for both rebound hammer method and ultrasonic pulse velocity method. The results were compared with those for different age or curing condition. The rebound numbers for concrete cured in air were larger than for concrete cured in water. The difference between rebound numbers for concrete cured in water and in air was larger than for concrete cured in water. The difference between rebound numbers for concrete cured in water and in air was larger when water cement ratio was high. Also, with the increase of age, the velocity of ultrasonic pulse for concrete cured in air was measured larger when compared with that in water.

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The Effect of Air Chamber Placed in Water Supply Piping System (급수배관계에서 에어 챔버의 설치효과에 관한 연구)

  • 이용화;최국광
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.14 no.12
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    • pp.1047-1055
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    • 2002

  • The present study is to investigate the pressure wave characteristics and the absorption of the maximum and minimum pressure generated by instantaneous valve closure and opening at the end of the straightening copper Piping system with and without an air chamber. Also, life of air chamber is investigated. Experiments were conducted under the following conditions: initial pressure of 1～5 bar, flow velocity of 0.5～3.0 m/s, water temperature of$20^{\circ}C$ and air chamber volume of 45.1～449.5$cm^3$ The results of the study can be used in sizing air chamber and selecting the water hammer absorbtion apparatus.

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