常规土类剪切波速与埋深的关系分析

Relationship between shear wave velocity and depth of conventional soils

土体剪切波速是土工地震减灾工程应用最广泛的参量之一。依据中国地震安评工作大量的钻孔实测剪切波速数据,定性探讨了常规土类剪切波速与埋深间的关系;利用最小二乘法分别采用线性模型、指数模型和一元二次多项式模型建立了分场地类别和不分场地类别两种情况下常规土类(不包括淤泥质土)–碎石土、砂土、粉土和黏性土剪切波速与埋深间的统计公式,以拟合优度为评价指标建议了常规土类的推荐模型及参数,并与《构筑物抗震设计规范》的经验公式及某一工程场地实测结果进行了对比分析。结果表明:除淤泥质土之外,其它常规土类剪切波速与埋深有显著的相关性;总体而言,一元二次多项式模型的拟合精度最高,所推荐的常规土类(不包括淤泥质土)剪切波速与埋深间的统计公式是较可靠的,可供无波速测试场地参考使用。

The shear wave velocity of soils is one of the most widely used parameters in the field of geotechnical earthquake engineering.Based on the measured data of shear wave velocity of soils from lots of boreholes obtained during seismic safety evaluation of engineering sites in China,the relationship between shear wave velocity and depth of soils is qualitatively discussed,and the regression equations of shear wave velocity and depth of conventional soils,including gravelly soil,sandy soil,silt,and cohesive soil,considering site classification and without considering site classification,except of muddy soil,are established by using three statistical models of the first-order linear equation,exponent equation and polynomial in one variable with two-order,respectively.The goodness of fitting is taken as an evaluation index to acquire the recommended models and parameters between shear wave velocity and depth of conventional soils,except of muddy soil.The equations recommended are compared with the formula in the Chinese design code for earthquake resistance of special structures（GB50191-93）.In addition,the results of shear wave velocity of some real site predicted using the recommended equations are compared with those of site measurement.The above results show that there is a remarkable relationship between the shear wave velocity and the depth of conventional soils,except of muddy soil,that the fitting accuracy of polynomial in one variable with two-order is the highest on the whole and that the regression equations of shear wave velocity and depth of most of conventional soils are more reliable,which can be used as a reference for sites,whose shear wave velocities are not tested.