Dynamic response of underground tunnels to earthquakes and moving train loads
Date Issued
2012
Date
2012
Author(s)
Cheng, Kai-Wen
Abstract
For their instant and convenient characteristics, mass rapid transit (MRT) systems have become one of the major transportation tools in metropolitan areas to resolve the traffic congestion caused by increasingly large population. Most MRT lines have been built as underground tunnels as the acquisition of urban lands has become too expensive. A typical MRT train is composed of a large number of carriages, which can move back and forth along the same lines for tens of times in one day to transport tens of thousands of passengers. Therefore, what the vast amount of trainloads will do to the underground tunnels is an issue of concern from the engineers’ point of view. Another concern is that Taiwan is an island located on the circum-Pacific seismic belt, which is exposed to frequent earthquakes each year. Due to the large volume of passengers carried by the MRT lines daily, if a major earthquake causes any damages on the underground tunnels and railways, the casualties incurred could be tremendous. Accordingly, the purpose of the thesis is to investigate the impact of both the moving train loads and earthquake effects on the underground tunnel structures using effective numerical simulation methods.
The soil-tunnel interaction system subjected to earthquakes will be analyzed using the coupled finite/infinite element approach proposed by Yang et al. (1996), with the earthquake excitations simulated by the technique proposed by Zhao and Valliappan (1993). The results obtained will be compared with those available in the literature. To simulate how the moving train actions affect the underground tunnel structure, considering particularly the rail surface irregularity, the 2.5D finite/infinite element method proposed by Yang and Hung (2001) is adopted, with the infinite elements used to model the radiation effect of infinite soil domains. Besides, parametric studies are conducted to examine the effect of various geometric and material parameters on the tunnel response.
Subjects
earthquake
frequency-domain analysis
half-space
infinite element
moving load
2.5D method
underground tunnel
Type
thesis
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