chapter  2
Inverse filtering procedure to correct cone penetration data for thin-layer and transition effects
ByR.W. Boulanger, J.T. DeJong
Pages 20

This paper presents an inverse filtering procedure for developing estimates of “true” cone penetration tip resistance and sleeve friction values from measured cone penetration test data in interlayered soil profiles. Results of prior studies of cone penetration in layered soil profiles are utilized for developing and evaluating the inverse filtering procedure. The inverse filtering procedure has three primary components: (1) a model for how the cone penetrometer acts as a low-pass spatial filter in sampling the true distribution of soil resistance versus depth, (2) a solution procedure for iteratively determining an estimate of the true cone penetration resistance profile from the measured profile given the cone penetration filter model, and (3) a procedure for identifying sharp transition interfaces and correcting the data at those interfaces. The details of the inverse filtering procedure presented herein were developed with a focus on liquefaction problems, but the concepts and framework should be applicable to other problems. Example applications of the inverse filtering procedure are presented for four CPT soundings illustrative of a range of soil profile characteristics. The proposed procedure provides an objective, repeatable, and automatable means for correcting cone penetration test data for thin-layer and transition zone effects.