The equipment for seabed cone penetration test (CPT) has a high working efficiency and can detect the strata continuously and vertically with a better data resolution.By analyzing 3 CPT boreholes and 1 geological borehole taken in the Yellow River Estuary,the strata of 20 meters below the seabed are divided into 5 layers.From top to bottom,they are silt,silty clay,silt interbedded with silty sand or silty sand,silty clay and silt,respectively.The CPT curves can give better reflections of special geological phenomena such as the hard crust layers in the silt and the shell interlayers in the silty clay.A regression equation suitable for the study area is obtained through the correlation analysis carried out between the CPT parameters and the physical-mechanical parameters of the silty clay.For evaluating the liquefaction potential of the surface silt in the study area,the methods for liquefaction evaluation based on CPT data are adopted,of which the Seed method and the Olsen method are considered to be accurate in predicting liquefaction resistance of sandy soils.By comparing the cyclic stress ratio (CSR) calculated by the Seed method with the cyclic resistance ratio (CRR) worked out by the Olsen method,it can be concluded that the surface silt in the study area won't be liquefied if the seismic fortification intensity is designed as 7 degree.If the seismic fortification intensity reaches 8 degree,however,the silt layer will be liquefied,with the calculated maximum liquefaction depth being 3.7 meters.%海床式静力触探设备工作效率高,能够实现从垂向上对地层的连续探测,数据分辨率较好.通过对黄河口海域3个静力触探孔和1个地质钻孔的分析,将研究区20 m以浅地层自上而下划分为粉土、粉质黏土、粉土夹粉砂或粉砂、粉质黏土、粉土五层,静力触探曲线对粉土层中的硬壳层和粉质黏土层中的贝壳夹层等特殊地质现象有很好的反映.对粉质黏土的静力触探参数与物理力学参数进行相关性分析,得到适合该区域的回归方程.采用基于CPT数据的液化判别法,对研究区表层粉土液化可能性进行评判,通过Seed简化法计算的周期应力比(CSR)与Olsen法计算的周期阻力比(CRR)的大小比较,得出当抗震设防烈度为7度时,研究区表层粉土不会液化,当抗震设防烈度为8度时,粉土层将发生液化,计算最大液化深度3.7 m.
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