PORE WATER PRESSURE RESPONSE OF SEABED IN ZHOUSHAN SEA AREA BASED ON IN-SITU OBSERVATION DURING TYPHOON LEKIMA

The response characteristics of pore water pressure in argillaceous seabed under typhoon are unclear. A typical muddy seabed in Zhujiajian, Zhoushan was selected as the research object, and the pore water pressure dynamic response of seabed in the observation area was studied at different depths by using the self-developed seabed pore water pressure probe rod combined with the hydrodynamic observation platform. The observation results show that the pore water pressure response type of muddy seabed in the observation area during typhoon Lichema is mainly transient response. The influence depth of waves on pore water pressure of seabed sediments increases with the increase of effective wave height, and the maximum influence depth can reach 3 meters. The amplitude attenuation rate of seabed pore water pressure in the observation area decreases with the increase of wave period, and the attenuation is obvious in the depth direction. At the same time, shallow gas in sediments will also lead to the amplitude attenuation of pore water pressure. The strong wave action caused by Typhoon Lichema can significantly reduce the effective stress in the shallow sediments of the seabed. The results reveal the response characteristics of pore water pressure of muddy seabed under typhoon, which is of great reference significance to judge whether typhoon will cause the instability of seabed surface.