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Post Processing of Cone Penetration to Assess Seismic Ground Hazards, with Specific Application to the New Madrid Seismic ZonePDF


Title:Post Processing of Cone Penetration to Assess Seismic Ground Hazards, with Specific Application to the New Madrid Seismic Zone
Author(s):Liao, Tianfei; Mayne, Paul W.
Subject(s):MAE Center
Abstract:The seismic cone penetration test (SCPTu) is the most efficient means for geotechnical site characterization and the evaluation of seismic ground hazards, as it provides up to 5 independent readings in a single sounding: cone tip stress (qT), sleeve friction (fs), penetration porewater pressure (ub), time rate of dissipation (t50), and downhole shear wave velocity (Vs). During SCPTu tests, a very large number of digital measurements are recorded. The overwhelming data provide more detailed information for engineering analysis, but also pose challenges in post-processing of “information overload”. In this thesis, software systems including ShearPro, ClusterPro, and InSituData, are developed to automate post processing of these SCPTu data. ShearPro is developed to automate the post-processing of the shear wave signals. ClusterPro uses the proposed threedimensional cluster analysis approach for soil stratification. InSituData facilitates the post processing of penetration data for seismic ground hazards analysis. A new threedimensional soil classification chart is also proposed in this thesis to help discern soil layers that may be subject to seismic ground hazards, such as loose liquefied sands and silty sands. These methods are then applied to SCPTu data collected at previously-identifed paleoliquefaction sites located in the New Madrid Seismic Zone (NMSZ). For liquefaction evaluation, the cyclic stress ratio (CSR) is computed using site response analysis by DeepSoil and a measured profile of shear waves derived from the 30-m SCPTU soundings and deep suspension loggings in AR and TN. The natural resistance of the soil to liquefaction, termed the cyclic resistance ratios (CRRs), is evaluated based on both deterministic procedures and probabilistic procedures. Based on liquefaction evaluation results at selected paleoliquefaction sites, regional CRR criteria for liquefaction are developed for the NMSZ. As even the latest major earthquakes in NMSZ occurred nearly 200 years ago, aging effects might be an important factor to consider in utilizing the liquefaction criteria to assess the seismic parameters associated with the previous earthquakes. The aging effects in the NMSZ were investigated through large scale blast-induced liquefaction tests conducted by the USGS and supplemented by the author by series of CPTs. Then a procedure to estimate seismic parameters associated with previous earthquakes is proposed. It utilizes both the liquefaction criteria based on SCPTu tests and the empirical attenuation relations developed for the corresponding regions. The approach is validated through data evaluation related to the 1989 Loma Prieta earthquakes in California and then applied to previous historic earthquakes in the NMSZ.
Issue Date:2007-03
Publisher:Mid-America Earthquake Center
Series/Report:MAE Center Report 07-09
Genre:Dissertation / Thesis
Technical Report
Publication Status:published or submitted for publication
Sponsor:NSF EEC-9701785
Date Available in IDEALS:2008-07-03

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