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UM E-Theses Collection (澳門大學電子學位論文庫)

Title

Pile Dynamics and its applications in Macau

English Abstract

The technology of Pile Dynamics was firstly introduced to Macau in 1990 by Laboratorio de Engenharia Civil de Macau, LECM. This latest developed technology can be used to estimate pile bearing capacity from the response of a simple hammer strike, which has resulted from the use of the one dimensional wave equation to examine the transmission of stress waves travelling in the pile. It is different to assumption that a force is generated instantly throughout the pile, as is done in deriving driving formulas. The main objective in using the wave-equation approach is to obtain a better relationship between the bearing capacity and pile-set than what can be obtained from a simple driving formula. The Pile Dynamics provide a mean of the bearing capacity estimation, namely as Dynamic Load Test. It allows studying the behaviour of a pile subjected to driving stress relationship, which allows an assessment to be made of the driveability of a pile with a particular set of piling equipment. The rational analysis of the piling stresses can be made and therefore it will be useful in the structural design of pile. In this investigation, an attempt had been made to improve the accuracy prediction of bearing capacity by the pile driving formulas and to use the wave equation computation to modify the Hiley formula. The formula is widely used in the pile driving design and in quality control in worldwide and in Macau. It had been found from this investigation that the performance of short piles and long piles were influenced differently by the effects of reflective tension wave and localized action of stress wave. A correction factor was developed in this study to predict the bearing capacity of pile of wave equation satisfactorily by Hiley formula. For emphasis the length effect of a pile during driving, it had been simplified the soil conditions as a uniform soil layer in this investigation, that is same SPT N60 from the top to the bottom of the soil. Different to this assumption, the ground conditions in Macau are not that with a same SPT N60 value from the top to the bottom in very many areas. For applying the correction factor, K, it is necessary to adopt a transformation of the actual site condition of the test poles to a simulated condition, so that the correction factor, K, is applicable. The necessary transformation included separating the toe resistance and weighted average to SPT N60 values of the pole shaft. Three poles had been tested to fail are by static loading and seven piles by Dynamic Load Test to obtain the ultimate bearing capacity. The test results were compared with the predicted pole bearing capacity using Hiley formula before and after modification. The correction factor obtained in this investigation was found quite satisfactory in improving the accuracy of prediction.

Issue date

1997.

Author

Ao, Peng Kong

Faculty

Faculty of Science and Technology

Department

Department of Civil and Environmental Engineering

Degree

M.Sc.

Subject

Piling (Civil engineering) -- Design

Foundations -- Design and construction

Supervisor

Subrahmanyam, M. S.

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Location
1/F Zone C
Library URL
991008400149706306