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    Item type:Publication,
    Development of tunneling influence zones for adjacent pile foundations by numerical analyses
    (2013-02-01)
    Jongpradist, Pornkasem
    ;
    Kaewsri, Theerapong
    ;
    Sawatparnich, Attasit
    ;
    Suwansawat, Suchatvee
    ;
    Youwai, Sompote
    In this study, three-dimensional elasto-plastic numerical analyses are conducted to investigate the influences of tunnel excavation on existing loaded piles. The effects of parameters on pile responses to be used as criteria for suggesting the influence zones can be captured from the analysis method. A large number of analyses are then carried out to generate the artificial data of pile responses from tunneling for establishing the influence zones. Deep and shallow tunneling are separately considered with their influence zones are suggested from the normalized pile settlement and the induced pile bending moment, respectively. The two zones are then combined. Based on the ground condition, geometries of the pile and the tunnel, tunnel construction method, and evaluated criteria considered in this study, the unique significant zones of influence for various conditions can be identified. © 2012 Elsevier Ltd.
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    Item type:Publication,
    Describing settlement troughs over twin tunnels using a superposition technique
    (2007-04-01)
    Suwansawat, Suchatvee
    ;
    Einstein, Herbert H.
    It has been observed in many tunneling projects that surface settlement troughs caused by twin tunnels have a variety of shapes unlike single tunnels, where symmetric surface settlement troughs are usually observed. The surface settlement troughs observed over twin tunnels can be symmetric with respect to the midpoint between the two tunnels or symmetric but shifted toward either side or they can also be asymmetric. Settlement troughs both over single and twin tunnels (when symmetric) can often be described by a Gaussian curve. Most of the cases reported in the literature do consider the effect of ground conditions, tunnel size, and depth on the surface settlement. However, these cases do not consider the effect of construction operation. A study of settlements above tunnels driven with earth pressure balance shields in Bangkok made it possible to include operational parameters such as face pressure, penetration rate, and grouting pressure. This is possible by comparing the effect of twin tunnels which are geometrically and geologically identical but differ in the operational characteristics. These operational differences make it, however, more difficult to describe the resulting settlement troughs over twin tunnels using existing methods. Therefore, this paper introduces a superposition technique to describe surface settlement troughs over twin tunnels. It appears that one can construct settlement curves induced by the first shield and the second shield using the Gaussian function and combine the curves to obtain a total settlement trough as a result of the twin tunnels. Using extensive data from the Bangkok Subway Tunnel project, this approach was found to be suitable both for twin tunnels excavated side-by-side and also for stacked twin tunnels. Right now this superposition technique is basically descriptive. Eventually it will be possible to use this approach to predict settlement troughs over twin tunnels. © ASCE.