Collaborative Research: Shear Wave Velocity Profiling by SASW Method at Selected Strong-Motion Stations, Liquefaction Sites, and Sites of Building Damage: 1999 Turkey Earthquakes

1999年土耳其的Kocaeli和Duzce地震在以下方面产生了重要的信息和数据：(1)记录了强烈的地面运动的站点，(2)发生了明显的土壤液化的站点，(3)局部地区有不同程度的建筑损坏。在研究这三种类型场地的地震反应时，一个关键变量是基础土壤的剪切刚度剖面。犹他州立大学（USU）和德克萨斯大学奥斯汀分校（UTA）的研究人员将进行一项联合研究，利用实地进行的地震测量来确定每个类别中的选定地点的特征。总共将调查约20个地点。地震测量将用于开发小应变剪切模量剖面，一些是一维的，一些是二维的，在这些地点的临界深度。剖面深度将从9米到60米不等，液化站点通常需要最浅的剖面，强震记录站需要最深的剖面。为了进行地震测量，将使用涉及瑞利型表面波的非侵入式地震测试技术。这种技术被称为表面波光谱分析（SASW）测试。该技术是非侵入式的，因为源和接收器都放置在地面上。在现场测量表面波色散（即以不同速度传播的不同波长的表面波），并在实验室使用正演模拟来评估现场的横波速度分布。在过去的18年里，UTA的研究人员已经成功地在陆地上的岩土工程场地使用了SASW测试。在20世纪90年代，犹他大学的研究人员在加利福尼亚州的液化场、固体废物填埋场和1989年洛马普里塔地震和1994年北岭地震所震动的强震站完成了大量的调查。在土耳其，以前的经验将用于优化选定站点的分析。例如，将在强震地点附近租用一台推土机，作为进行深度剖析的工具。水滴重量源，可以很容易地在土耳其制造，将用于剖面较浅的深度。拟议中的项目至关重要，因为它提供了受Kocaeli和Duzce地震影响的重要地点的广泛横波速度特征。SASW测试是评估横波速度剖面的最经济有效的方法。从这项研究中获得的横波速度数据将与地震工程和地震学界共享，并将证明对未来的研究项目非常宝贵。

CMS-0085257BayThe 1999 Kocaeli and Duzce earthquakes in Turkey have generated important information and data at: (l) stations where strong ground motions were recorded, (2) sites where significant soil liquefaction occurred, and (3) localized areas with widely varying building damage. One key variable in investigating the earthquake response at these three types of sites is the shear stiffness profile of the foundation soils. A joint study will be conducted by researchers at Utah State University (USU) and the University of Texas at Austin (UTA) to characterize selected sites in each category using seismic measurements made in the field. A total of about 20 sites will be investigated. The seismic measurements will be used to develop small-strain shear modulus profiles, some one-dimensional and some two-dimensional, over critical depths at the sites. Profiling depths will range from 9 to 60 m, with liquefaction sites generally requiring the shallowest profiles and strong motion recording stations requiring the deepest profiles.To perform the seismic measurements, a non-intrusive seismic testing technique involving Rayleigh-type surface waves will be used. This technique is called spectral-analysis-of-surface-waves (SASW) testing. The technique is non-intrusive because both the source and receivers are placed on the ground surface. Measurement of surface wave dispersion (i.e. surface waves of differing wavelengths travelling at different velocities) is performed in the field and forward modeling is used in the laboratory to evaluate the shear wave velocity profile at the site. Researchers at UTA have been successfully using SASW testing at geotechnical sites on land for the past 18 years. During the 1990's, UTA researchers completed numerous investigations in California at liquefaction sites, solid-waste landfills, and strong motion stations shaken by the 1989 Loma Prieta and 1994 Northridge earthquakes. In Turkey, this previous experience will be used to optimize profiling at the selected sites. For instance, a bulldozer, which will be rented locally near the strong-motion sites, will be used as a source for deep profiling. A drop-weight source, which can be readily fabricated in Turkey, will be used in profiling the shallower depths.The proposed project is critical because it provides extensive shear wave velocity characterization of important sites shaken by the Kocaeli and Duzce earthquakes. SASW testing is the most cost-effective method for evaluating shear wave velocity profiles. The shear wave velocity data obtained from this study will be shared with the earthquake engineering and seismological communities and will prove invaluable to future research projects.