Model test of coastal excavations is based on the excavation of Gongbei tunnel located in the Ling-ding Ocean

which is a part of the famous Hong Kong-Zhuhai-Macao Bridge project. The physical size of the testing model is determined by theory of similar scale. A series of model tests are carried out in the multifunctional wave-current flume to study the pore pressure response to wave around clayey silt excavation. This study shows that the excess pore pressure around near-sea excavation consists of oscillatory and accumulated excess pore pressure. For the oscillatory excess pore pressure

the amplitude decreases and the lagging phase increases gradually along the seepage path from the active zone to the passive zone of the excavation; and the more amplitude attenuated

the more phase lagged. Excess pore pressure accumulates at a rate decreasing with time. The worse of the drainage condition or the larger of the dynamic stress generated by the wave load

the easier for the excess pore pressure to accumulate. The oscillatory and accumulated excess pore pressures are all relatively small in the passive zone of the excavation.