港口结构抗震设计方法的发展(3)

Development of seismic design of port and harbor structures: part 3

以我国、美国和日本的港口码头设计规范、手册为基础,对我国、美国和日本港口码头抗震设计的方法进行了分析,同时介绍了国际航运协会标准《港口结构抗震设计指南》的有关规定。此系列论文共分6部分,该文为第3部分。分析和对比了上述规范中抗震设计时场地类别划分、地基液化判别、动主动土压力和动被动土压力的计算方法。对比表明,我国、美国和日本场地土的分类方法相似,但划分的类别数不同。对于地基液化,我国规范通过土的地质年代、黏粒含量和标准贯入击数采用两步判别法进行判别;美国港口设计手册采用地震剪应力方法进行判别;日本的液化判别方法比较复杂,采用土的均匀系数、标准贯入击数、等效加速度和循环三轴试验进行综合判别。对于动土压力计算,各规范都采用经典的物部-冈部公式或以该公式为基础改进的公式。

A comparative study is made on seismic design of port and harbor structures based on Chinese code,US guidelines and Japanese standards as well as guideline of International navigation association.This is the third of the series papers and the method for classification of site,evaluation of subgrade liquefaction,calculation of dynamic active and passive earth pressure acting on the structure in these codes are analyzed.It is shown that the methods for classification of site in these codes are similar but with different numbers.For evaluation of subgrade liquefaction,two step methods are used based on geological time,clay content and SPT counts in Chinese code.Soil shear stress method under earthquake excitation is adopted in US guideline.In Japanese code,a set of parameters based on uniformity coefficient,SPT,equivalent peak acceleration of ground motion and triaxial test are used for evaluation of subgrade liquefaction.For calculation of dynamic earth pressure,the Mononobe-Okabe equation or its modified formats are used in these codes.