NEESR-II: Study of Surface Wave Methods for Deep Shear Wave Velocity Profiling Applied to the Deep Sediments of the Mississippi Embayment

NEESR-II：应用于密西西比湾深层沉积物的深剪切波速度剖面表面波方法研究

• 批准号: 0530140
• 负责人: Brent Rosenblad
• 金额: $ 20万
• 依托单位: University of Missouri-Columbia
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-10-01 至 2008-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0530140&HistoricalAwards=false
• 关键词: NEESR; II; Study; Surface; Wave

ABSTRACTThe primary objective of this research project is to study testing methodologies for non-intrusively measuring shear wave velocity (VS) profiles of very deep sediments using low-frequency surface waves. Surface wave methods have become an accepted means to characterize soil deposits for site response studies and have compared well to established borehole methods. Several active-source surface wave methodologies, having varying degrees of sophistication and efficiency, currently exist. None of these methods, however, has been studied for application to the problem of very deep profiling (300 m and greater) of sediments. Most studies in the last 20 years have focused on the top 30 m with very few studies extending beyond a depth of 100 m. With the advent of the Network for Earthquake Engineering Simulation (NEES) large-scale field shakers, it is now possible to actively generate the low-frequency energy (down to 1.0 Hz) that is required for very deep soil profiling. Field studies will be conducted at several sites in the Central United States using a variety of data collection and data processing methodologies. The findings from this work will be applicable at other deep soil sites in seismically active regions around the country, including Salt Lake City, Utah, Los Angeles, California, and Charleston, South Carolina. The deep VS profiles derived from these studies will provide an additional benefit by filling a gap in the current state of knowledge of the stiffness structure of the deep soils of the Mississippi Embayment. Predicting the ground response in this seismically active region requires knowledge of the deep sediment structure, which extends to depths of 1000 m in some areas. Recent studies of the ground response in this region have been limited by a lack of knowledge of the deep soil stiffness structure. While the near-surface sediments (top 30 m) are generally well characterized, very few measurements have been performed to depths greater than 100 m. The VS profiles measured during these studies will be important input parameters for site response studies in this region. The findings from this work will be disseminated to the engineering community through peer-reviewed publications. Also, data sets will be placed on the NEES repository and will be a valuable resource for other researchers in this field. Educational field modules, demonstrating important concepts such as site resonance and soil liquefaction, will be developed by undergraduate students. These field educational modules will be included in demonstrations of this state-of-the-art field testing equipment to rural and minority K-12 students in the Central United States.

本课题的主要目的是研究非侵入式测量极深沉积物剪切波速度剖面的测试方法 使用低频表面波。 面波方法已成为一种公认的手段，以表征土壤沉积物的现场响应研究，并比较以及建立钻孔方法。 目前存在几种具有不同复杂程度和效率的有源表面波方法。 然而，这些方法中没有一种被研究应用于沉积物极深剖面（300米及以上）的问题。 在过去的20年里，大多数研究都集中在顶部30米，很少有研究超过100米的深度。 随着地震工程模拟网络（NEES）大型现场振动台的出现，现在可以主动产生非常深的土壤剖面所需的低频能量（低至1.0 Hz）。 将使用各种数据收集和数据处理方法在美国中部的几个地点进行实地研究。 这项工作的结果将适用于全国地震活跃地区的其他深层土壤场地，包括犹他州的湖城、加州的洛杉矶和南卡罗来纳州的查尔斯顿。 从这些研究中得出的深层VS剖面将填补密西西比湾深层土壤刚度结构知识的空白，从而提供额外的好处。 预测这一地震活跃区的地面反应需要了解深层沉积物结构，在某些地区，这种结构延伸到1000米的深度。 由于对深层土体刚度结构的认识不足，限制了对该地区地基响应的研究。 虽然近地表沉积物（顶部30米）的特征一般都很好，但在100米以上深度进行的测量很少。 在这些研究期间测量的VS配置文件将是该区域现场响应研究的重要输入参数。 这项工作的结果将通过同行评审的出版物传播给工程界。 此外，数据集将被放置在NEES存储库中，并将成为该领域其他研究人员的宝贵资源。 教育领域的模块，展示了重要的概念，如现场共振和土壤液化，将由本科生开发。 这些实地教育模块将包括在向美国中部的农村和少数民族K-12学生演示这种最先进的实地测试设备中。