Investigation of Piezocone Dissipation Test Interpretation in Clay Accounting for Vertical and Horizontal Porewater Pressure Dissipation with a Large Deformation Axisymmetric Penetration Model

Authors

Diane Moug, Portland State University
Andrew Huffman, Portland State University
Jason T. DeJong, University of California, Davis

Published In

Frontiers in Built Environment

Document Type

Article

Publication Date

5-30-2024

Subjects

Soil remediation, Soil liquefaction, Soil stabilization

Abstract

The piezocone (CPTu) dissipation test is used to characterize how the applied load from the penetrating cone is distributed between the soil and pore fluid during both penetrometer advancement and when penetration is paused. The coefficient of consolidation is often estimated from CPTu dissipation tests by interpreting the rate of excess porewater pressure (∆u) decay to static conditions during a pause in cone penetration. Most CPTu dissipation test interpretation methods are based on Terzaghi consolidation theory for ∆u dissipation at the cone shoulder (u₂ position) or cone face (u₁ position) and assume that radial ∆u dissipation dominates the response. However, several recent studies show that vertical ∆u migration does contribute to the response. This study uses a large deformation direct axisymmetric cone penetration model to characterize the soil-water mechanical response during CPTu dissipation tests, and in particular, the role of vertical ∆u dissipation on the response at the u₁ and u₂ positions. Large deformations around the penetrating cone are accommodated with an Arbitrary Lagrangian Eulerian approach. Soil behavior is modeled with the MIT-S1 constitutive model calibrated for Boston blue clay (BBC) soil behavior. ∆u dissipation following undrained cone penetration is simulated with coupled consolidation for BBC with over-consolidation ratios (OCR) of 1, 2, and 4 and a range of hydraulic conductivity anisotropy. The simulated u₁ and u₂ dissipation responses are presented to study how they are affected by OCR and hydraulic conductivity anisotropy. A correction factor is recommended to account for hydraulic conductivity anisotropy when interpreting the horizontal coefficient of consolidation from CPTu dissipation tests.

Rights

© 2024 Moug, Huffman and DeJong. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

Locate the Document

https://doi.org/10.3389/fbuil.2024.1386803

DOI

10.3389/fbuil.2024.1386803

Persistent Identifier

https://archives.pdx.edu/ds/psu/41973

Citation Details

Moug, D., Huffman, A., & DeJong, J. T. (2024). Investigation of piezocone dissipation test interpretation in clay accounting for vertical and horizontal porewater pressure dissipation with a large deformation axisymmetric penetration model. Frontiers in Built Environment, 10.