一种建筑工程场地参数VS30的外推模型修正方法

Method for correcting extrapolation model of engineering site parameter VS30

摘要:

为提高覆盖土层较浅工程场地上钻孔的外推V_S30值精度,选取日本KiK-net台站中符合一定条件的钻孔数据,利用相关系数矩阵排除共线性问题以确定可用于回归的3个体现钻孔剖面特性的参数,通过最优子集法建立常数外推V_S30残差与这3个参数的优选函数关系,利用调整后R²、贝叶斯信息准则和k倍交叉验证3种特征选择方法确定其中的最优关系。根据修正后预测V_S30与实际观测V_S30间残差均值和标准差的分布给出推荐的常数外推模型修正函数。结果表明,该V_S30的外推模型能够较好提高底部常速度模型的预测精度,并且在新疆地区具有一定适用性。提出的方法可以对中国不同地区的场地V_S30经验估计模型建立提供参考。

Abstract:

To improve the accuracy of the extrapolated V_S30 values of boreholes on engineering sites with shallow overburden, this paper selects certain borehole data from KiK-net database for research. The correlation coefficient matrix was adopted to test the collinearity of parameters, and three parameters that can reflect the characteristics of borehole profiles were determined. Through the optimized subset method, the relationship functions between the residuals of V_S30 estimated by bottom constant velocity (BCV) model and the three selected parameters were established. On the basis of three feature selecting methods including adjusted R², Bayesian information criterion, and k-fold cross-validation, the optimal function was proposed. According to the distribution of mean and standard deviation of residuals between predicted and observed V_S30 values, a correction function of BCV model was proposed. Results show that the extrapolation model of V_S30 could improve the prediction accuracy of BCV model, and it was applicable in Xinjiang region. The method proposed in this paper can provide reference for developing empirical models for estimating V_S30 in other regions of China.