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earth quake modelling using Geoslope 2012

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  • Dynamic Modeling

    With QUAKE/W

    An Engineering Methodology

    June 2013 Edition

    GEO-SLOPE International Ltd.

  • Copyright 2004-2013 by GEO-SLOPE International, Ltd.

    All rights reserved. No part of this work may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or by any information storage or retrieval system, without the prior written permission of GEO-SLOPE International, Ltd.

    Trademarks: GEO-SLOPE, GeoStudio, SLOPE/W, SEEP/W, SIGMA/W, QUAKE/W, CTRAN/W, TEMP/W, AIR/W and VADOSE/W are trademarks or registered trademarks of GEO-SLOPE International Ltd. in Canada and other countries. Other trademarks are the property of their respective owners.

    GEO-SLOPE International Ltd

    1400, 633 6th Ave SW

    Calgary, Alberta, Canada T2P 2Y5

    E-mail: info@geo-slope.com

    Web: http://www.geo-slope.com

  • QUAKE/W Table of Contents

    Page i

    Table of Contents

    1 Introduction ......................................................................................... 1 1.1 Key issues ........................................................................................................................... 1

    1.2 Inertial forces ....................................................................................................................... 2

    1.3 Behavior of fine sand .......................................................................................................... 3

    Loose contractive sand ................................................................................................. 3

    Dense dilative soils ....................................................................................................... 5

    1.4 Permanent deformation ...................................................................................................... 7

    1.5 Concluding remarks ............................................................................................................ 8

    2 Numerical Modeling: What, Why and How ......................................... 9 2.1 Introduction ......................................................................................................................... 9

    2.2 What is a numerical model? ................................................................................................ 9

    2.3 Modeling in geotechnical engineering ............................................................................... 11

    2.4 Why model? ...................................................................................................................... 13

    Quantitative predictions .............................................................................................. 13

    Compare alternatives ................................................................................................. 15

    Identify governing parameters .................................................................................... 16

    Understand physical process - train our thinking ....................................................... 17

    2.5 How to model .................................................................................................................... 20

    Make a guess ............................................................................................................. 20

    Simplify geometry ....................................................................................................... 21

    Start simple ................................................................................................................. 22

    Do numerical experiments .......................................................................................... 23

    Model only essential components .............................................................................. 24

    Start with estimated material properties ..................................................................... 25

    Interrogate the results ................................................................................................. 26

    Evaluate results in the context of expected results .................................................... 26

    Remember the real world ........................................................................................... 26

    2.6 How not to model .............................................................................................................. 27

    2.7 Closing remarks ................................................................................................................ 28

    3 Geometry and Meshing .................................................................... 29 3.1 Introduction ....................................................................................................................... 29

    3.2 Geometry Objects in GeoStudio ....................................................................................... 30

    Soil Regions, Points and Lines ................................................................................... 31

    Free Points ................................................................................................................. 33

  • Table of Contents QUAKE/W

    Page ii

    Free Lines ................................................................................................................... 33

    Interface Elements on Lines ....................................................................................... 34

    Circular Openings ....................................................................................................... 36

    3.3 Mesh Generation ............................................................................................................... 37

    Structured mesh ......................................................................................................... 38

    Unstructured quad and triangle mesh ........................................................................ 38

    Unstructured triangular mesh ..................................................................................... 38

    Triangular grid regions ................................................................................................ 39

    Rectangular grid of quads .......................................................................................... 40

    3.4 Surface layers ................................................................................................................... 40

    3.5 Joining regions .................................................................................................................. 43

    3.6 Meshing for transient analyses ......................................................................................... 44

    3.7 Finite Elements ................................................................................................................. 45

    3.8 Element fundamentals ...................................................................................................... 46

    Element nodes ............................................................................................................ 46

    Field variable distribution ............................................................................................ 46

    Element and mesh compatibility ................................................................................. 47

    Numerical integration .................................................................................................. 49

    Secondary variables ................................................................................................... 50

    3.9 General guidelines for meshing ........................................................................................ 50

    Number of elements ................................................................................................... 51

    Effect of drawing scale ............................................................................................... 51

    Mesh purpose ............................................................................................................. 52

    Simplified geometry .................................................................................................... 53

    4 Material Properties ............................................................................ 55 4.1 Introduction ....................................................................................................................... 55

    4.2 Soil behavior models ......................................................................................................... 55

    Linear-elastic model ................................................................................................... 56

    Equivalent linear model .............................................................................................. 56

    Non-Linear model ....................................................................................................... 57

    4.3 Shear modulus .................................................................................................................. 59

    Granular soils ............................................................................................................. 60

    Cohesive soils ............................................................................................................ 61

    4.4 G-reduction function .................................................