苏州城区深软场地土剪切波速与土层深度的经验关系

Empirical relationship between shear wave velocity and soil depth on deep soft sites in urban area of Suzhou city

苏州地处长江下游冲湖积平原,第4系沉积土层发育,土层深厚、松软,远震、大震的长周期地震动对苏州城区的重大工程有可能造成严重震害。结合海侵地质成因,分析了苏州城区深软场地52个钻孔剖面的剪切波速资料,发现剪切波速与土层深度的关系:40m以上浅土层基本符合线性函数分布,40m以下深土层基本符合幂函数分布;依据考虑和不考虑土体分类2种情况,给出了采用线性函数、幂函数分段形式拟合的苏州城区深软场地剪切波速随土层深度变化的经验关系,为苏州城区深软场地重大工程建设的场地地震效应评价提供了有益的基础性资料。

Urban area of Suzhou city locates on the alluvial or lacustrine plain in the lower reaches of Yangtze River, which is covered by Quaternary sedimentary soil layer. Because of the thick and soft layer, long-period ground motion of far earthquake or great earthquake may cause serious damage to some important engineering projects in this area. Based on analyzing shear wave velocity data of 52 drilling hole profiles, combining geological genesis of transgression, the relationship between shear wave velocity and soil depth of deep soft sites can be found that the distribution of them accords with linear function above the soil depth of 40 meters, and accords with power function under deeper than the soil depth of 40 meters. According to two cases with and without considering soil classification, both empirical relationships fitting with piecewise linear function and power function between the shear wave velocity and the soil depth of deep soft sites in urban area of Suzhou city are obtained. This beneficial basic information can be provided to seismic effect evaluation of important engineering projects on deep soft sites in urban area of Suzhou city.