Soil Profile Database and Site Classification for National Strong-Motion Stations in Western China

Abstract

Abstract As part of a broader effort to develop ground-motion data resources for China in a manner consistent with Next Generation Attenuation projects, we develop a database of geotechnical soil profiles and shear-wave velocity (VS) logs for sites having ground-motion accelerometers (this database is referred to as soil profile database [SPD]), and then use that data to develop site parameters. The site information is compiled for stations within the National Strong Motion Observation Network System (NSMONS) of China. This effort is focused on four provinces in western China (Yunnan, Sichuan, Gansu, and Xinjiang), which contribute 871 of 2023 NSMONS stations throughout China. Of the 871 sites, the SPD provides site information for 678 sites, or 78% of the total. To develop the SPD, geotechnical logs and/or VS profiles are compiled for 637 sites. This information is derived from previously unpublished reports and is assembled here in a uniform format and partially disseminated (only approximate site locations are provided). The remaining 41 sites in the SPD have confirmed bedrock conditions at the ground surface. Site metadata and parameters are compiled into a database, included as a supplemental material to this article, that includes the depth to the first occurrence of 0.5 km/s shear-wave velocity (Z0.5), three time-averaged shear-wave velocity parameters (VSe, VS20, VS30), and site classifications based on the Chinese building seismic design code and National Earthquake Hazards Reduction Program Provisions. For sites with VS profiles that do not extend to 30 m, we present region-specific recommendations for extrapolating time-averaged velocities from the profile depth to 30 m. For sites with geotechnical logs but no profiles, we present procedures to estimate VS profiles from which the earlier parameters can be derived.