In site monitoring of wave-induced pore pressure of silt in Chengdao sea area of Yellow River Estuary
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摘要: 波浪会对海床产生反复的作用力，由此引起的土体颗粒间孔隙水压力变化是造成土体液化的主要原因。使用自行研发的孔压监测设备，对黄河口埕岛海域易液化区海底孔压进行了长时间、高精度的观测，并对孔隙水压力、波高以及潮位间的关系进行分析。监测结果显示，本次监测条件下波浪最大作用深度介于0.5～1.5 m之间，超过该作用深度后孔压无明显变化。土体内部孔隙水压力的变化主要由潮位和波高决定，潮位的作用可使孔压缓慢平滑的变化且对超孔压无影响；波高的作用可使孔压快速、剧烈地振荡并导致超孔压的出现。Abstract: Variation of pore pressure between soil particles, which caused by the cyclic loading from waves to seabed, is the main reason for soil liquefaction. By using a self-designed pore pressure monitoring equipment, we monitored pore pressure with a long-period, high-precision way in the easy-liquefied zone in Chengdao sea area of Yellow River Estuary. The monitoring results show that the maximum wave-affected depth is between 0.5 m to 1.5 m and no obvious pore pressure response in the deeper sediment during this period. Pore pressure variation in soil is mainly determined by tide level and wave height. Tide level changes can result in smooth change in pore pressure but can not cause the emergence of excess pore pressure while wave height changes can result in severe oscillation in pore pressure and lead to the appearance of excess pore pressure.
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图 6 总孔隙水压力、波高及潮位随时间的变化
a–d曲线分别代表海床以下0.5 m、1.5 m、2.5 m和3.5 m位置孔压变化，S表示有明显孔压响应条件的区域
Fig. 6 Total pore pressure, wave height and tide level vary with time
a–d represent pore pressure variation in 0.5 m、1.5 m、2.5 m and 3.5 m depth under the seabed. S represents the area that pore pressure response obviously
图 8 无潮位孔隙水压力（即为总孔隙水压力减去潮位变换引起的水压力）
a–d曲线分别代表海床以下0.5 m、1.5 m、2.5 m和3.5 m位置孔压变化
Fig. 8 Total pore pressure without tide level’s affection (obtained by total pore pressure minus pore pressure induced by tide)
a–d represent pore pressure variation in 0.5 m、1.5 m、2.5 m and 3.5 m depth under the seabed
表 1 参数统计结果
Tab. 1 Statistics result of parameters
黏粒含量/% 含水量/% 容重/kN·m−3 孔隙比 平均 10.94 25.74 19.72 15.70 数据个数 108 156 151 147 标准差 4.01 3.15 0.55 0.81 液限/% 塑限/% 黏聚力/kPa 内摩擦角/(°) 平均 0.71 27.75 20.00 16.11 数据个数 147 152 152 131 标准差 0.08 2.97 2.15 5.06 
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