Developing confidence in critical state soil confidence in critical state soil mechanics 5. Modified...

download Developing confidence in critical state soil confidence in critical state soil mechanics 5. Modified Cam Clay (MCC) Mike Jefferies, PEng Dr. Dawn Shuttle, PEng January, 2015 ... Implementing

of 11

  • date post

    14-Mar-2018
  • Category

    Documents

  • view

    219
  • download

    1

Embed Size (px)

Transcript of Developing confidence in critical state soil confidence in critical state soil mechanics 5. Modified...

  • Developing confidence in critical state soil mechanics

    5. Modified Cam Clay (MCC)

    Mike Jefferies, PEng

    Dr. Dawn Shuttle, PEng

    January, 2015

  • Why Modified Cam Clay (MCC) ?

    February 11, 2016 2

    vp

    q

    p

  • Modified vs Original Cam Clay

    OCC MCC

    Flowrule

    Yield Surface

    Hardening

    February 11, 2016 3

    M=

    2 pc

    p1

    M=1 ln

    p

    pc

    = MD p

    &pc

    pc=

    1+ e

    &v

    p

    Dp =

    M2 2

    2

    &pc

    pc=

    1+ e

    &v

    p

  • Stress dilatancy (= flowrule)

    February 11, 2016 4

    Mod Cam ClayOriginal Cam Clay

    Nova

    Rowe

    M

  • 5

    0

    0.2

    0.4

    0.6

    0.8

    1

    1.2

    1.4

    1.6

    1.8

    -1 -0.5 0 0.5 1 1.5

    Dp

    D662D667

    jjjjqjq

    jjjjvjvp

    jGqq

    KppD

    3/)()(

    /)()(

    111,1,

    111,1,

    ++

    ++

    =

    Stress dilatancy of Erksak sand

  • Implementing MCC

    Make copy of the OCC worksheet

    Rename it MCC

    Change

    Spacing ratio to 2

    Dp equation to MCC dilation

    equation to MCC yield surface

    MCC is pathological on dilation

    Must kludge the spreadsheet

    Switch to incrementing volumetric strain for first ~0.5% strain

    Thereafter revert to incrementing shear strain

    February 11, 2016 6

  • 7

    Implementing MCC by modifying MCC sheet

  • 8

    Implementing MCC by modifying MCC sheet

  • Over to you

    February 11, 2016 9

  • Computed soil response

    February 11, 2016 10

    Original Cam ClayModified Cam Clay

  • Mod Cam Clay

    Improved theory simply shows lack of understanding

    Work dissipation is unclear / unreasonable

    Mathematically pathological to implement

    Does not fit any known soil data

    February 11, 2016 11