Pore pressure response of silt seabed during storms-taking Zhoushan Zhujiajian sea area as an example
The pore water pressure in seabed sediments is sensitive to hydrodynamic changes,and inves-tigating the response of pore water pressure in sediments under different sea conditions is of great sig-nificance to the study of seabed instability and dynamic evolution of seabed boundary layer.In the sea area of Zhoushan Zhujiajian,Zhejiang Province,the dynamic changes of the hydrodynamic conditions and the pore water pressure of seabed sediments at 1m,3m,5m and 7m below the sea bed before and after typhoon Lekima were recorded by using the pore water pressure monitoring system.The monito-ring data showed that the variation of pore water pressure in seabed sediments was affected by hydro-static pressure and sediment properties,and had obvious response to wave action in short term.During the typhoon,the hydrodynamic force was greatly enhanced,and the effective wave height could reach more than 5 times of that under the calm sea condition.The oscillation amplitude of the excess pore water pressure in the sediment at the shallow 1m layer could reach 1-2 kPa,and the change of the ex-cess pore pressure value was strong consistently with the wave strength.In the process of wave load acting on seabed sediment,the wave pressure had obvious amplitude attenuation,and the attenuation could reach more than 70％at the shallow layer of 1 meter.The influence of waves could be almost ig-nored below 1 meter.The influence of rod stop plate was an important reason for the attenuation of pore pressure amplitude.The presence of gas in seabed sediments and the interaction between shallow active silt layer and waves could significantly reduce the influence of wave load on seabed pore water pressure,which was an important factor of wave energy consumption.
in-situ observationpore water pressureLichmaamplitude attenuation
NETL
NSTL
万方数据
