天津地区覆盖土层剪切波速与埋深的相关性分析

Correlation analysis between shear wave velocity and depth of covering soils in Tianjin

剪切波速是划分场地类别和判别土层动力特性的重要量化指标。基于天津地区地震安评的实测剪切波速资料,采用幂函数模型,定性探讨了常见土类剪切波速与埋深的相关性,给出了考虑和不考虑场地类别情况下常见土类剪切波速与埋深的经验关系并与已有成果进行了对比分析,同时研究了土体状态对剪切波速的影响规律,最后以典型场地实测结果为例,验证了本文预测模型的可靠性。结果表明:除了淤泥质土和松散人工填土,天津地区的常见土类剪切波速与埋深存在明显的相关性,剪切波速离散性随埋深增加而增大;剪切波速与埋深的经验公式受土层区域特性的影响显著;考虑土体状态和场地类别可以大幅度地提高经验公式预测精度。

Shear wave velocity is a quantitative indicator for site classification. Based on the shear wave velocity data obtained during seismic safety evaluation of engineering sites in Tianjin, the correlation analysis between the shear wave velocity and depth of common soils is qualitatively discussed. And then, the regression equations of the shear wave velocity and depth of common soils are conducted respectively with and without considering site classification. In addition, during the comparison of the regression equation recommended and the existing results, the influence of soil state on the shear wave velocity is further studied. At last, a typical case is taken as an example to verify the reliability of the results obtained in this paper. The above research shows that there is a remarkable correlation between the shear wave velocity and depth of common soils in Tianjin except muddy soil and shallow artificial fill, that the regression equation of shear wave velocity and depth shows obvious regionally, and that the fitting accuracy of the quadratic function model is the highest in whole and the prediction accuracy could be higher when the state of soils is considered.