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Understanding Micro- and Macro-Mechanics of Soil Liquefaction: A Necessary Step for Field-Scale Assessment

Citation

Mital, Utkarsh (2016) Understanding Micro- and Macro-Mechanics of Soil Liquefaction: A Necessary Step for Field-Scale Assessment. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/Z9PV6HB0. http://resolver.caltech.edu/CaltechTHESIS:05092016-151847908

Abstract

Liquefaction is a devastating instability associated with saturated, loose, and cohesionless soils. It poses a significant risk to distributed infrastructure systems that are vital for the security, economy, safety, health, and welfare of societies. In order to make our cities resilient to the effects of liquefaction, it is important to be able to identify areas that are most susceptible. Some of the prevalent methodologies employed to identify susceptible areas include conventional slope stability analysis and the use of so-called liquefaction charts. However, these methodologies have some limitations, which motivate our research objectives. In this dissertation, we investigate the mechanics of origin of liquefaction in a laboratory test using grain-scale simulations, which helps (i) understand why certain soils liquefy under certain conditions, and (ii) identify a necessary precursor for onset of flow liquefaction. Furthermore, we investigate the mechanics of liquefaction charts using a continuum plasticity model; this can help in modeling the surface hazards of liquefaction following an earthquake. Finally, we also investigate the microscopic definition of soil shear wave velocity, a soil property that is used as an index to quantify liquefaction resistance of soil. We show that anisotropy in fabric, or grain arrangement can be correlated with anisotropy in shear wave velocity. This has the potential to quantify the effects of sample disturbance when a soil specimen is extracted from the field. In conclusion, by developing a more fundamental understanding of soil liquefaction, this dissertation takes necessary steps for a more physical assessment of liquefaction susceptibility at the field-scale.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Soil Liquefaction, Triaxial compression test, Liquefaction charts, Shear Velocity
Degree Grantor:California Institute of Technology
Division:Engineering and Applied Science
Major Option:Applied Mechanics
Awards:Caltech Three Minute Thesis 3MT® competition, 2016, 2nd Place Winner & People’s Choice
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Andrade, Jose E.
Thesis Committee:
  • Lapusta, Nadia (chair)
  • Andrade, Jose E.
  • Asimaki, Domniki
  • Ampuero, Jean-Paul
Defense Date:29 April 2016
Non-Caltech Author Email:utmital (AT) gmail.com
Funders:
Funding AgencyGrant Number
CaltechUNSPECIFIED
THORUNSPECIFIED
Record Number:CaltechTHESIS:05092016-151847908
Persistent URL:http://resolver.caltech.edu/CaltechTHESIS:05092016-151847908
DOI:10.7907/Z9PV6HB0
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1007/s11440-015-0430-8DOIArticle adapted for ch. 2
ORCID:
AuthorORCID
Mital, Utkarsh0000-0001-9794-382X
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:9712
Collection:CaltechTHESIS
Deposited By: Utkarsh Mital
Deposited On:16 May 2016 16:52
Last Modified:16 May 2016 18:08

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