Nondestructive Characterization of Liquefaction Features Using Ground Penetrating Radar

使用探地雷达对液化特征进行无损表征

• 批准号: 9412666
• 负责人: Glenn Rix
• 金额: $ 0.97万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-06-01 至 1995-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9412666&HistoricalAwards=false
• 关键词: Nondestructive; Characterization; Liquefaction; Features; Using

9412666 Rix The January 17, 1994 Northridge Earthquake (M=6.6) caused liquefaction-induced ground failures in the San Fernando valley, Simi valley, and Redondo Beach areas. Of particular interest were the liquefaction features (sand boils and ground fissures) observed in the abandoned reservoir ("debris basin") upstream of the Lower San Fernando Dam. Free-field accelerations as large as 0.90 g (horizontal) and 0.60 g (vertical) were observed at California Strong Motion Instrumentation Program (CSMIP) stations in the vicinity of the dam. Although sand boils and fissures offer valuable surface evidence of liquefaction, they reveal little about the subsurface nature of the liquefaction. This project uses ground penetrating radar (GPR) tests to image the observed liquefaction features nondestructively. GPR uses electromagnetic waves to image the subsurface, resulting in a representation of the site stratigraphy that is similar to a seismic reflection cross section. The objective is to perform GPR tests along several lines to image the surface along which lateral spreads developed, and along several closely spaced lines to generate a three-dimensional image of a sand boil. It is anticipated that detailed subsurface images of these liquefaction features will be useful in planning subsequent site investigations. The project uses a global positioning system (GPS) receiver to measure the topography of the area of the ground penetrating radar measurements. These GPS measurements allow the radar data to be corrected for topographic effects. ***

1994年1月17日的北岭地震（M=6.6）在圣费尔南多山谷、西米谷和雷东多海滩地区造成了液化引起的地面破坏。特别令人感兴趣的是在圣费尔南多大坝下游上游的废弃水库（“碎屑盆地”）中观察到的液化特征（砂沸腾和地裂缝）。在大坝附近的加州强震仪器项目（CSMIP）观测站观测到的自由场加速度可达0.90 g（水平）和0.60 g（垂直）。虽然砂沸腾和裂缝提供了宝贵的地表液化证据，但它们对液化的地下性质揭示得很少。该项目使用探地雷达（GPR）测试对观测到的液化特征进行无损成像。探地雷达利用电磁波对地下进行成像，从而获得类似于地震反射截面的现场地层表示。目标是沿着几条线进行探地雷达测试，以成像横向扩散形成的表面，并沿着几条紧密间隔的线进行探地雷达测试，以生成砂沸腾的三维图像。预计这些液化特征的详细地下图像将有助于规划随后的现场调查。该项目采用全球定位系统（GPS）接收机对探地雷达测量区域的地形进行测量。这些GPS测量允许雷达数据对地形影响进行校正。＊＊＊