浅海圆柱形人工岛结构地震响应

根据能量守恒原理导出计算人工岛自振频率的能量公式,浅海人工岛可按剪切型结构进行动力计算,动水压力和动土压力对结构振型参与系数的影响很小,可以忽略。地震时人工岛内回填土只有一部分有效质量参与地震响应,通过模型试验,高径比小于1/3的人工岛回填土有效质量系数在0.2左右。有效质量系数随土壤粘结力的增大而提高,随高径比的增大而增大。一般圆柱形人工岛结构的振型参与系数可采用1.2。

Seismic response of circular artificial island in shallow sea

Under earthquake excitation,part of the back filled soil inside of the artificial island will vibrate.Through model tests,it has been found that the effective mass coefficient for the soil is around 0.2 for artificial islands with height-to-diameter ratio being smaller than 1/3.Increasing the stickiness of the soil or increasing the height-to-diameter ratio will both make the effective mass coefficient bigger.The formula for natural frequency of the island has been derived based on energy conservation principle.Shear models can be used to calculate the dynamic response of the island in shallow sea.Neither hydrodynamic force nor dynamic soil pressure has big effects on the model participating coefficient(which is normally 1.2).The simple formula,very useful to engineering design,is recommended to calculate the hydrodynamic forces on artificial islands in shallow sea.