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| LATERAL VIBRATION PROPERTIES OF PARTIALLY EMBEDDED PILE GROUPS FOUNDATION CONSIDERING AXIAL FORCES |
| REN Qing1，HUANG Maosong2，3，HAN Dongxiao1 |
| (1. Department of Civil Engineering，University of Shanghai for Science and Technology，Shanghai 200093，China；2. Department of Geotechnical Engineering，Tongji University，Shanghai 200092，China；3. Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education，Tongji University，Shanghai 200092，China) |
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Abstract For offshore engineering，dynamic characteristics of supporting system of foundation are extremely important for the stability and security of upper structures. Based on the Euler-Bernoulli beam model，transfer matrix method is used to establish lateral vibration model for the partially embedded single pile considering the coupling effect of lateral load and vertical load. The main influence factors for impedance and effective pile length are analyzed；and the shortages of existing theory are indicated and also amended. The pile-pile interaction is studied from three aspects，i.e. length ratio，wave incidence angle and axial force；and a simplified approach for calculating partially embedded pile groups is put forward on the basis of superposition theory. Furthermore，solutions of the proposed model are compared with theoretical results for fully embedded pile groups. Through the discussion of parameters，it is concluded that the axial force(N)，pile spacing(s/d) and length ratio(L1/L2) are very important for the lateral vibration properties of partially embedded pile groups，which cannot be ignored by designers. Finally，the introduced model is used to study the effects of lateral vibration properties of the pile groups for an offshore wind power plant and variation of impedance of the pile groups foundation on natural vibration characteristics of overall structure.
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Received: 27 April 2011
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2011, Vol. 30 
