Soil Profiling at the Geotechnical Experimentation Site of Treasure Island, CA

剪切波的速度与波传播的岩土材料的刚度和密度直接相关。 可以将土壤沉积物的材料特性与测量的剪切波速相关联；准确的剪切波速度剖面被认为提供了评估土壤沉积物动态响应的重要数据，特别是对强烈地震地面震动的响应。 测量穿过土壤沉积物的剪切波速度的现有方法，例如稳态瑞利波方法（SSRW）和表面波频谱分析方法（SASW），有其局限性。 该项目的一个目标是在金银岛岩土工程试验场研究一种新方法的能力，称为受控源表面波谱分析（CSSASW），它结合了 SSRW 和 SASW 方法的特点。 金银岛属于美国海军，是毗邻旧金山湾耶尔巴布埃纳岛的一座人造岛屿。 海军正在该岛上开辟一个场地，用于基础研究土壤沉积物对地震引起的强烈地面运动的动态响应，以及一般岩土工程实验 - 例如该项目旨在研究 CSSASW 方法用于场地表征的用途。 预计该实验还将在该金银岛遗址提供更多有价值的地下数据，这将有助于将该遗址用作国家岩土工程研究设施。

The velocity of a shear wave is directly related to the stiffness and density of the geotechnical material through which the wave propagates. It is possible to correlate material properties of a soil deposit to the measured shear wave velocity; and accurate shear wave velocity profiles are recognized as providing essential data on which to evaluate the dynamic response of soil deposits, in particular to strong earthquake ground shaking. Existing methods for measuring shear wave velocities through soil deposits, such as the steady-state Rayleigh wave method (SSRW) and the spectral-analysis-of-surface-waves method (SASW), have their limitations. An objective of this project is to investigate at the Treasure Island geotechnical experimentation site the capability of a new method, referred to as the controlled-source spectral- analysis-of-surface-waves (CSSASW), which combines features of the SSRW and SASW methods. Treasure Island, which belongs to the U.S. Navy, is a man-made island adjacent to Yerba Buena Island in San Francisco Bay. The Navy is making a site on this island available for basic research into the dynamic response of soil deposits to earthquake-induced strong ground motions, and for general geotechnical engineering experiments - such as this project to investigate the use of the CSSASW method for site characterization. It is expected that this experiment will also provide additional valuable subsurface data at this Treasure Island site which will contribute to the use of this site as a national facility for geotechnical engineering research.