江苏东部平原区VS30经验预测模型和场地分类

Empirical Prediction Model for VS30 and Site Classification in the Eastern Jiangsu Plain Area

摘要:

江苏东部平原区地震风险较高,深厚松软的覆盖层也会加重震害程度,研究该地区场地地震动效应非常重要。V_S30是反映场地地震动效应的关键参数之一,在缺乏钻孔数据或钻孔深度不足的情况下,需要建立合适的模型对V_S30值进行预测。本文基于江苏东部平原区的地震安全性评价报告等资料,建立了一个包含678个深钻孔的数据库。利用6种V_S30外推模型,对数据库中的钻孔数据进行回归分析,进而建立了江苏模型。随后评估和对比各模型的预测效果,最后给出在此类滨海平原区域最适用的V_S30外推模型为DEA13江苏模型。将江苏模型和其他外推模型的系数进行对比,发现模型系数存在显著差异,验证了V_S30外推模型的区域性。此外,还探讨和验证了基于地形坡度、基于第四纪沉积物深度的预测模型在本研究区的适用性,结果显示这两类模型在本研究区的表现不佳。最后,探讨了场地类别与V_S30值的关系,并给出了在江苏东部平原区Ⅲ、Ⅳ类场地的V_S30边界值。在地质条件与本研究区相似的滨海平原地区,推荐使用DEA13江苏模型推导浅钻孔场地的V_S30值。研究结果为本地区提供了可靠的V_S30预测模型和数据支持,推动了区域地震动模型的构建和地震灾害评估的开展,也为区域地震灾害风险评估提供了科学依据。

Abstract:

The eastern plain of Jiangsu Province faces high seismic risk,and its thick,soft overlying layers can worsen earthquake damage. Studying site seismic effects in this region is crucial. V_S30 is a key parameter for assessing site seismic effects. When borehole data are lacking or shallow,models are needed to predict V_S30 values. This study created a database of 678 deep boreholes from seismic safety reports for the region. Six V_S30 extrapolation models were used for regression analysis,resulting in the development of the Jiangsu model. The predictive performance of these models was evaluated,with the DEA13 Jiangsu model proving most suitable for coastal plain areas like the study region. A comparison of the Jiangsu model's coefficients with others revealed significant regional differences,confirming the need for region-specific models. The study also examined terrain-based and Quaternary sediment depth-based models,which performed poorly in the area. Finally,the relationship between site classification and V_S30 values was investigated,and the boundary V_S30 values for Site Classes Ⅲ and Ⅳ in the eastern Jiangsu Plain were determined. For coastal plains with similar geological conditions,the DEA13 Jiangsu model is recommended for shallow borehole V_S30 predictions. This study provides a reliable V_S30 model and data support for regional seismic hazard assessments,contributing to seismic risk evaluation in similar coastal plains.