Browsing by Author "Cooper, Jon"

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    Robust identification and characterization of thin soil layers in cone penetration data by piecewise layer optimization
    Cooper, Jon; Martin, Eileen R.; Yost, Kaleigh; Yerro Colom, Alba; Green, Russell (Elsevier, 2021-08-11)
    Cone penetration testing (CPT) is a preferred method for characterizing soil profiles for evaluating seismic liquefaction triggering potential. However, CPT has limitations in characterizing highly stratified profiles because the measured tip resistance ($q_c$) of the cone penetrometer is influenced by the properties of the soils above and below the tip. This results in measured $q_c$ values that appear ``blurred" at sediment layer boundaries, inhibiting our ability to characterize thinly layered strata that are potentially liquefiable. Removing this ``blur" has been previously posed as a continuous optimization problem, but in some cases this methodology has been less efficacious than desired. Thus, we propose a new approach to determine the corrected $q_c$ values (i.e. values that would be measured in a stratum absent of thin-layer effects) from measured values. This new numerical optimization algorithm searches for soil profiles with a finite number of layers which can automatically be added or removed as needed. This algorithm is provided as open-source MATLAB software. It yields corrected $q_c$ values when applied to computer-simulated and calibration chamber CPT data. We compare two versions of the new algorithm that numerically optimize different functions, one of which uses a logarithm to refine fine-scale details, but which requires longer calculation times to yield improved corrected $q_c$ profiles.