山东地区场地剪切波速经验外推模型及其适用性  

EMPIRICAL EXTRAPOLATION MODEL OF SITE SHEAR WAVE VELOCITY AND ITS APPLICABILITY IN SHANDONG PROVINCE

作　　者：李志恒 谢俊举[1] 李柯苇 温增平[1] 李小军[4] 王志才[2] 许洪泰[2] 赵晓芬 张娜 LI Zhi-heng;XIE Jun-ju;LI Ke-wei;WEN Zeng-ping;LI Xiao-jun;WANG Zhi-cai;XU Hong-tai;ZHAO Xiao-fen;ZHANG Na(Institute of Geophysics,China Earthquake Administration,Beijing 100081,China;Shandong Earthquake Agency,Jinan 250014,China;School of Earth and Space Sciences,Peking University,Beijing 100871,China;College of Architecture and Civil Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]中国地震局地球物理研究所,北京100081 [2]山东省地震局,济南250014 [3]北京大学地球与空间科学学院,北京100871 [4]北京工业大学城市建设学部,北京100124

出　　处：《地震地质》2024年第4期934-954,共21页Seismology and Geology

基　　金：国家重点研发计划项目(2022YFC3003503,2020YFA0710603);山东省地震局科研项目(YB2407);山东省海洋地震观测研究团队(TD202401)共同资助

摘　　要：场地剪切波速是进行场地分类和定量估计场地对地震动影响的重要参数,在工程抗震设防和震后震害快速评估等方面具有广泛应用。文中利用山东地区1336个工程场地的剪切波速剖面数据,分别基于常速度外推方法、速度梯度外推方法和条件独立方法建立了山东地区场地剪切波速V_(S20)和V_(S30)的经验外推模型。研究结果表明,常速度外推方法对较浅的钻孔进行波速外推时会产生明显的低估,且预测误差较大。速度梯度外推方法的拟合结果表现出明显的区域性特征,山东地区的V_(S30)预测结果与美国加州和北京平原地区的结果相比,总体上较为接近,但明显低于日本地区。综合考虑建立的3种区域外推模型的精度和预测误差,文中建议优先采用基于条件独立方法建立的山东地区的V_(S20)和V_(S30)经验外推模型,获得的波速外推结果可以较好地为山东地区场地分类提供依据。Site shear wave velocity is a pivotal parameter for site classification and for quantitatively assessing the site’s impact on ground motion.It has extensive applications in engineering seismic design and rapid post-earthquake damage assessment.China’s seismic design standard,GB50011-2010,primarily uses two indicators for site classification:the thickness of the soil layer and the equivalent shear wave velocity of the top 20m of soil.In contrast,the United States and Europe utilize the average shear wave velocity,V_(S30),at a 30m depth for site classification.Studies have indicated that considering only the top 20m of soil in classification overlooks the influence of deeper low-velocity layers on long-period structures.Additionally,reliance on the top 20m’s shear wave velocity can be problematic due to its sensitivity to the properties of the fill layer and the potential unreliability of measurements in this shallow depth.To address these issues,scholars in China advocate increasing the depth considered in site classification from 20m to 30m.Current standards focus on soil layers not exceeding 20m,resulting in engineering boreholes and shear wave velocity measurements that rarely exceed this depth,especially in harder sites where boreholes often extend less than 10m.The development of site shear wave velocity extrapolation models is crucial for accurate site classification and ground motion parameter determination,particularly in the absence of deep borehole data.Various extrapolation methods have been proposed,including the constant velocity method,velocity gradient method,and conditional independence method.The constant velocity method assumes a uniform velocity below the measured depth,while the velocity gradient method fits empirical relationships in a linear or logarithmic form.The conditional independence method leverages correlations between instantaneous and average shear wave speeds at various depths.Domestic research has led to the establishment of regional shear wave velocity extrapolation models,

关 键 词：场地分类 外推模型 平均剪切波速 适用性 V_(S30) 

分 类 号：P315.9[天文地球—地震学]