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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 81
Edited by: B.H.V. Topping
Paper 210

The Isolation Efficiency of the Dual-Trench System in a Three Dimensional Wave Propagation Problem

S.H. Tung+, C.C. Yu+, W.H. Lee+ and M.H. Shih*

+Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
*Department of Construction Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung, Taiwan

Full Bibliographic Reference for this paper
S.H. Tung, C.C. Yu, W.H. Lee, M.H. Shih, "The Isolation Efficiency of the Dual-Trench System in a Three Dimensional Wave Propagation Problem", in B.H.V. Topping, (Editor), "Proceedings of the Tenth International Conference on Civil, Structural and Environmental Engineering Computing", Civil-Comp Press, Stirlingshire, UK, Paper 210, 2005. doi:10.4203/ccp.81.210
Keywords: vibration reduction, trench, boundary element method, three-dimensional wave propagation.

The isolation or reduction of the vibration induced by machine and high speed railways has received extensive discussion [3,4,5,6,7,8,9,10,11] in recent years. Three major solutions are trenches, springs with dampers and the impediment of waves. Because the construction of a trench is simpler than the other two, it receives more attention [4,5,6,7,8,9,10]. Much research is carried out on two-dimensional systems without considering the real effect of the three-dimensional wave propagation.
Figure 210.1: Isolation efficiency of different trench systems in various frequency cases.
(a) Single trench (b) Dual-trench system

There is much research on vibration isolation using a single trench. A previous study [3] indicates that the isolation efficiency of a trench varies with the fill material. The trench with stiffer material has better isolation efficiency in a low frequency case and the empty trench has better isolation efficiency in a high frequency case. In the present analysis, the efficiency of a combination isolation system of two parallel trenches is evaluated with the aid of the boundary element method [1,2].

The efficiency of the vibration isolation of a dual-trench system is investigated in the present analysis. Three different dual-trench systems, the open-open, open-infilled, and infilled-infilled combinations are studied. The research results are shown in Figure 210.1, which show that the system with open-open or infilled-infilled trenches have the similar efficiency to that of a single open or single infilled trench. The combination system of open-infilled trenches is an ideal isolator in both low and high frequency cases.

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