Study of hydrodynamic pressure acting on wall structure shaking elastically

In the Hamaoka Nuclear Power Station, we constructed the tsunami protection wall along coastline around the site, following the tsunami disaster of The 2011 off the Pacific coast of Tohoku Earthquake on March 11, 2011. It is general design procedure to utilize the Westergaard equation in case of designing the wall structure such as the tsunami protection wall even in consideration of hydrodynamic pressure. However there is an issue to apply the Westergaard equation in our case. Because the Westergaard equation could be essentially applied for only the rigid wall, however the seismic behavior of the tsunami protection wall is considered to be elastic oscillations and also the depth of tsunami in front of the tsunami protection wall is fluctuant due to the effect by the dune embankment along coastline. Therefore, we implemented the geotechnical centrifuge experiment modeled with the tsunami protection wall as well as the actual coastal topography, and performed the simulation analysis. As a consequence of the experiment, we revealed that the hydrodynamic pressure acting on the wall shaking elastically in the upper side of wall, which receives the amplification of shaking, has a substantial difference comparing to the case of the rigid wall. Also, as the result of the simulation analysis, we revealed that both the added mass model based on Westergaard equation and the liquid element model have applicability to the simulation but the liquid element could be better to represent the hydrodynamic pressure more accurately. (author)