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Investigation of Lateral Stress Relief on theStability of PHI = 0 DEG Slopes Using Laboratory, Fracture Mechanics, and Finite Element Method Approaches

Kutschke, Walter (2011) Investigation of Lateral Stress Relief on theStability of PHI = 0 DEG Slopes Using Laboratory, Fracture Mechanics, and Finite Element Method Approaches. Doctoral Dissertation, University of Pittsburgh.

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    Abstract

    Total stress analyses of purely cohesive cut slopes utilize the undrained shear strength for slope stability analyses. These slopes can have an in-situ lateral earth pressure that is greater than the vertical pressure. Excavations into these materials results in expansion of the slope face due to release of confining pressure. When strains exceed that which can be internally absorbed through elastic deformation, failure planes or cracks may develop at the toe of the slope. However, conventional limit equilibrium methods of slope stability analysis do not account for the in-situ stress conditions or the development of shear zones or cracks that occur from lateral stress relief. Progressive failure of the slope may occur if internal lateral stresses are large enough to cause stress concentrations in front of the advancing toe cracks. Finite element methods using substitution methods reveal two distinct shear cracks at the toe of slope consisting of a horizontal and an inclined failure plane while a tension zone develops in the backslope region. The formation and extension of the shear cracks are strongly dependent on ko and they can extend to approximately 1/4 of the slope height due to initial lateral stress relief. Classical limit equilibrium solutions regarding the critical slope height have been revised to account for lateral stress relief. Analyses indicate good agreement with published case histories and they reveal how the shear zones propagate to create progressive slope failure in stiff clay slopes under total stress analyses.


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    Item Type: University of Pittsburgh ETD
    ETD Committee:
    ETD Committee TypeCommittee MemberEmailORCID
    Committee ChairVallejo, Luis Evallejo@pitt.edu
    Committee MemberIannacchione, Anthonyati2@pitt.edu
    Committee MemberLin, Jeen-Shangjslin@pitt.edu
    Committee MemberVandenbossche, Juliejmv7@pitt.edu
    Committee MemberSmolinski, Patrickpatsmol@pitt.edu
    Title: Investigation of Lateral Stress Relief on theStability of PHI = 0 DEG Slopes Using Laboratory, Fracture Mechanics, and Finite Element Method Approaches
    Status: Unpublished
    Abstract: Total stress analyses of purely cohesive cut slopes utilize the undrained shear strength for slope stability analyses. These slopes can have an in-situ lateral earth pressure that is greater than the vertical pressure. Excavations into these materials results in expansion of the slope face due to release of confining pressure. When strains exceed that which can be internally absorbed through elastic deformation, failure planes or cracks may develop at the toe of the slope. However, conventional limit equilibrium methods of slope stability analysis do not account for the in-situ stress conditions or the development of shear zones or cracks that occur from lateral stress relief. Progressive failure of the slope may occur if internal lateral stresses are large enough to cause stress concentrations in front of the advancing toe cracks. Finite element methods using substitution methods reveal two distinct shear cracks at the toe of slope consisting of a horizontal and an inclined failure plane while a tension zone develops in the backslope region. The formation and extension of the shear cracks are strongly dependent on ko and they can extend to approximately 1/4 of the slope height due to initial lateral stress relief. Classical limit equilibrium solutions regarding the critical slope height have been revised to account for lateral stress relief. Analyses indicate good agreement with published case histories and they reveal how the shear zones propagate to create progressive slope failure in stiff clay slopes under total stress analyses.
    Date: 27 June 2011
    Date Type: Completion
    Defense Date: 31 March 2011
    Approval Date: 27 June 2011
    Submission Date: 02 April 2011
    Access Restriction: No restriction; The work is available for access worldwide immediately.
    Patent pending: No
    Institution: University of Pittsburgh
    Thesis Type: Doctoral Dissertation
    Refereed: Yes
    Degree: PhD - Doctor of Philosophy
    URN: etd-04022011-114710
    Uncontrolled Keywords: finite element methods; fracture mechanics; lateral stress relief; stiff clay
    Schools and Programs: Swanson School of Engineering > Civil and Environmental Engineering
    Date Deposited: 10 Nov 2011 14:33
    Last Modified: 06 Apr 2012 15:17
    Other ID: http://etd.library.pitt.edu/ETD/available/etd-04022011-114710/, etd-04022011-114710

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