Effect of a circular tunnel in the foundation soil on the seismic response of dikes

This study report describes a computer simulation of the dynamic response of a dike built on the clay foundation using PLAXIS 2D 2015. Importance is given to the comparison of Horizontal Peak Ground Acceleration at different horizontal placement of points and varying tunnel diameter. For an in-depth analysis, other ground readings such as Peak Ground Velocity and Peak Ground Displacement are also compared. A dry sand dike of 12 m crest span, 60 m base width and 8 m height is selected as the model in this study. The seismic inputs adopted for the simulation study involved an actual past earthquake acceleration data, using the SMC data of an earthquake (Upland, 1990). The effect of a circular tunnel at different horizontal placement and the effect of different circular tunnel size are the 2 main variable interests. For varying tunnel diameter, there is a trend of increasing PGA with increasing tunnel diameter size. For varying horizontal location, the increasing distance of tunnel away from the dike shows an increasing acceleration experienced at every point. However, another finding is at the location of 30 m away from dike (Toe of dike) shows the highest PGA for all different cases of horizontal tunnel placement. This study hopes to inform that having a tunnel in the ground would affect the ground surface acceleration.Bachelor of Engineering (Civil