First Advisor

Diane Moug

Term of Graduation

Winter 2024

Date of Publication

3-18-2024

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Civil & Environmental Engineering

Department

Civil and Environmental Engineering

Language

English

Subjects

Calcareous sand, Cone penetration test, CPT, Finite difference modeling, Numerical analysis, Numerical modeling

Physical Description

1 online resource (vi, 27 pages)

Abstract

The cone penetration test (CPT) is used to characterize the behavior and properties of soils, including the susceptibility to earthquake liquefaction triggering. The cone tip resistance relates to liquefaction susceptibility through relative density, where relative density is closely related to both cone tip resistance and liquefaction susceptibility. Currently, published methods of estimating liquefaction potential (i.e., cyclic resistance ratio) are based on silica sands and do not properly characterize calcareous sands. The measured cone tip resistance in calcareous sands is lower than in silica sands at the same relative density; this difference is generally attributed to the higher compressibility of calcareous sands due to particle crushing during cone penetration. Consequently, application of CPT-based liquefaction triggering evaluations in calcareous sands result in over-conservative analysis. To avoid over-conservative analysis, projects may develop site-specific correction factors to adjust the cone tip resistance in calcareous sand to the equivalent value in silica sand at the equivalent relative density, which is time and cost intensive. This study aims to investigate cone penetration in calcareous sands compared to silica sands by examining the roles of soil compressibility and other fundamental soil parameters. The study is performed with a direct axisymmetric penetration model and the MIT-S1 constitutive model calibrated against published mechanical behavior for a calcareous sand; the simulated cone penetration results are compared with simulated cone penetration in Ottawa F-65 sand. Compressibility of the calibrations is adjusted to explore the role of compressibility on cone tip resistance. The numerical results show that differences in compressibility only partially account for differences in cone tip resistance between calcareous and silica sands at the same initial state. However, the results support that critical state line position does strongly relate to differences in cone tip resistance between the two soil types. The study results provide a basis to investigate differences in critical state line position as a basis for site-specific cone tip resistance correction factors for calcareous soils.

Rights

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Persistent Identifier

https://archives.pdx.edu/ds/psu/41698

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