波浪引起海床土体液化的概率研究

首先根据波浪荷载在海床内产生的循环应力比和海床土体的循环阻抗比，采用可靠性分析法，建立土体抗液化安全余量的表达式。根据一次二阶矩法，考虑波浪和土体参数的变异性，计算了黄河口水下三角洲埕岛海域某石油平台附近场地在6、8和10级风浪下的液化概率。风浪等级越大，抗液化安全系数越小，液化概率越大。如果该场地要求液化概率控制在5％以内，安全系数需大于1.8，可靠指标需大于1.6。然后分析了参数变异性对可靠指标的影响，得出波高比波长和土体标贯击数比黏粒含量对液化可靠指标的影响大的结论。最后研究了参数之间的互相关性对液化可靠指标的影响，对可靠指标大于零的情况，忽略参数之间的互相关性会得到偏大的可靠指标，高估海床土体的抗液化性能。

Study on probability of seabed soil liquefaction induced by wave

The safety margin expression of soil anti liquefaction was established based on reliability analysis according to the cyclic stress ratio induced by wave and cyclic resistance ratio in seabed. The probability of liquefaction was calculated by using first order second moment (FOSM) method with the variability of wave and soil properties taken into account. The proposed method is applied to calculate the liquefaction probability of an oil platform foundation located at the river mouth delta of Yellow River. The result shows that the anti liquefaction safety factor decreases as the storm wave grade increases and the probability increases correspondingly. If the probability is controlled within 5%, the safety factor must be greater than 1.8, and the reliability index should be higher than 1.6. The influence of variability of wave and standard penetration test number (SPT-N) to reliability is greater than those of wave length and clay content respectively. Finally, the influences of co relationship between parameters to reliability index were discussed.