【摘要】 以福州市区场地软土动力特性和地脉动频谱结构为研究对象,对福州市区进行了场地地脉动的测试及频谱分析。据此研究了地脉动频谱结构特征及场地土(包括软土)对地脉动的频率响应的特性。结果表明,场地地脉动卓越周期与场地覆盖层厚度和地基土刚度的变化密切相关;软土层对地脉动的卓越周期有一定放大作用;通过建立场地土覆盖层厚度、剪切波速与地脉动卓越周期之间的相关关系,揭示了场地卓越周期值与场地土覆盖层厚度正相关,随剪切波速增大,场地卓越周期呈现减小的趋势。同时,根据已有对市区高层建筑结构自振周期的地脉动测试结果,结合我国经验计算方法和美国加州近似方法,得到高层建筑结构自振周期的修正近似计算式。最后,研究结果初步揭示了深厚软土地层地震破坏的作用机理,并结合震害案例进一步解释此类场地某些结构物易遭地震破坏的原因。更多还原

【Abstract】 A study of seismic failure mechanism of soft soil sites in Fuzhou is presented. The characteristics of frequency-spectrum structure and response of ground soils,including soft soils and the frequency of ground micro-tremor,were investigated. From the results,it is found that the site soft soil enlarges predominant period of ground micro-tremor to some degree,and the predominant period of ground micro-tremor has a close relationship with the stiffness of the foundation soils. The correlations among the predominant period of ground micro-tremor, the overburden thickness of soils,and the shear wave velocity of overburden,are established. These relations reveal that the predominant period of the ground micro-tremor is positively proportional to overburden thickness, but decreases with the increase of shear wave velocity. In addition,based on the completed measurements of the natural periods of the buildings in the city,using the empirical calculation methods,and approximate calculation methods applied in California,USA,the improved approximate calculation formulae are developed for natural periods of high-rise buildings. The results reveal the seismic failure mechanism in the abundant soft soil sites,and demonstrate the causes of potential seismic failures for some buildings.更多还原