| In this dissertation, the performance of the underground trench, used as a barrier to muffle vibration was investigated using the Finite Element Method. A two-dimensional Finite Element Program was developed and verified by examining several known experimental vibration results: for the beam, 2D plate, and the open trench. The code was found to agree reasonably well with the experimental results obtained by other researchers for these three well-characterized experimental situations. It was then used to investigate the usefulness of the underground trench as a barrier for surface vibrations. Using surface vibration amplitude to judge the effectiveness of a particular underground trench configuration it was possible to obtain qualitative results of vibration isolation which are consistent under different situations. It was then possible to study the effectiveness of the underground trench structure in detail. The Taguchi Method for experiment design was used to optimize the various parameters that define an idealized underground trench structure. It has been found that the effectiveness of the underground trench structure is comparable with that of the open trench if the structure parameters are chosen carefully. Computer visualization of the stress wave propagation was employed to clearly show the effectiveness of underground trenches for surface vibration isolation. |
