NEW TOOL FOR GEOTECHNICAL STABILITY AND DEFORMATION ANALYSIS

Transcription

1 Seminar Indian Geotechnical Society CRRI New Delhi Feb 2014 NEW TOOL FOR GEOTECHNICAL STABILITY AND DEFORMATION ANALYSIS Kristian Krabbenhoft 1,2,3) 1) Optum Computational Engineering 2) University of Newcastle, NSW, Australia 3) University of Southern Denmark, Odense, Denmark 1

2 OUTLINE Company and products Theoretical background to Optum G2 Applications Conclusions 2

3 COMPANY Optum Computational Engineering (Optum CE) Founded 2013 by: Kristian Krabbenhoft, CEO Andrei Lyamin, CTO Jorgen Krabbenhoft, CFO Mission: Develop and market advanced user-friendly finite element software for civil engineering applications 3

4 COMPANY What does user-friendly mean? Two kinds of products on the market: 1. General purpose finite element software (ABAQUS, FLAC, PLAXIS, etc). Typically used only by experts 2. Specialized programs for particular problems foundations, slopes, retaining walls, etc. 4

5 COMPANY What does user-friendly mean? Two kinds of products on the market: 1. General purpose finite element software (ABAQUS, FLAC, PLAXIS, etc). Typically used only by experts 2. Specialized programs for particular problems foundations, slopes, retaining walls, etc. Easy-of-use Generality 5

6 COMPANY What does user-friendly mean? Two kinds of products on the market: 1. General purpose finite element software (ABAQUS, FLAC, PLAXIS, etc). Typically used only by experts 2. Specialized programs for particular problems foundations, slopes, retaining walls, etc. Easy-of-use Specialized Generality 6

7 COMPANY What does user-friendly mean? Two kinds of products on the market: 1. General purpose finite element software (ABAQUS, FLAC, PLAXIS, etc). Typically used only by experts 2. Specialized programs for particular problems foundations, slopes, retaining walls, etc. Easy-of-use Specialized General purpose Generality 7

8 COMPANY What does user-friendly mean? Two kinds of products on the market: 1. General purpose finite element software (ABAQUS, FLAC, PLAXIS, etc). Typically used only by experts 2. Specialized programs for particular problems foundations, slopes, retaining walls, etc. Easy-of-use Optum G2 Specialized General purpose Generality 8

9 COMPANY What does user-friendly mean? Typical issues preventing true user-friendliness: - Primitive CAD interface for problem definition - Non-intuitive sequencing of operations - Use of menus, sub-menus, sub-sub-menus - Numerical problems (inadequate algorithms) - Unnecessarily tedious work flow due to limitations of the calculation core, e.g. excavations In conclusion: two kinds of issues: 1. Those related exclusively to bad design 2. Those related to a combination of bad design and calculation core limitations 9

10 COMPANY The ADVANCED SIMPLICITY paradigm: 10

11 COMPANY The ADVANCED SIMPLICITY paradigm: Use ADVANCED algorithms and computational technology in combination with state-of-the-art principles of human-computer interaction to achieve a maximum of SIMPLICITY from the point of view of the user 11

12 COMPANY The ADVANCED SIMPLICITY paradigm: Use ADVANCED algorithms and computational technology in combination with state-of-the-art principles of human-computer interaction to achieve a maximum of SIMPLICITY from the point of view of the user Ultimate goal: make advanced calculation tools readily available to all engineers rather than a select few experts 12

13 COMPANY The ADVANCED SIMPLICITY paradigm: Use ADVANCED algorithms and computational technology in combination with state-of-the-art principles of human-computer interaction to achieve a maximum of SIMPLICITY from the point of view of the user Ultimate goal: make advanced calculation tools readily available to all engineers rather than a select few experts NOTE: it is unrealistic and also unnecessary to expect that the user should be an expert in every facet of the calculation core. Rather, the user should focus on defining reasonable input and interpret the output. 13

14 OPTUM G2 CAD interface for problem definition Stage Manager for defining linked construction stages Materials database Structural elements (walls, anchors, etc) Analysis types include: Limit Analysis Strength Reduction Elastoplastic Seepage Initial Stress Analysis 14

15 OPTUM G2 CAD interface for problem definition Stage Manager for defining linked construction stages Materials database Structural elements (walls, anchors, etc) Analysis types include: Limit Analysis Strength Reduction Elastoplastic Seepage Initial Stress Analysis 15

16 LIMIT ANALYSIS Lower bound theorem: A body of elastic-plastic materials will not collapse under a stress field that satisfies: Equilibrium Static boundary conditions Yield condition Hence the corresponding load is a lower bound

17 LIMIT ANALYSIS Lower bound theorem: A body of elastic-plastic materials will not collapse under a stress field that satisfies: Equilibrium Static boundary conditions Yield condition Hence the corresponding load is a lower bound Optimization problem: maximize load subject to equilibrium conditions static BC yield condtion

18 LIMIT THEOREMS t Lower bound requirements: T T b 0 inv Equilibrium N t on S Static BCs F( ) 0 Yield condition where: (,, ) x y xy T T / x 0 / y nx 0 n T y, 0 / y / x N 0 ny n x Lower bound optimization problem: maximize subject to N T T b 0 inv t F( ) 0 ons

19 LIMIT ANALYSIS Upper bound theorem: For a displacement field that satisfies: The strain-displacement relations The associated flow rule Kinematic boundary conditions the ratio of the internal to external work is higher than or equal to that actually found at collapse. Hence an upper bound on the collapse load is obtained

20 LIMIT THEOREMS t Upper bound requirements: u F( ) Strain-displacement + assoc flow rule where: u T F ( ux, uy), F( ), / x 0 0 / y / y / x Upper bound optimization problem: minimize V subject to u F( ) S udv tuds T T 0 1 V T b uds

21 LIMIT THEOREMS t Upper bound requirements: u F( ) Strain-displacement + assoc flow rule where: u T F ( ux, uy), F( ), / x 0 0 / y / y / x Finally, discretize by finite elements: Upper bound optimization problem: minimize V subject to u F( ) S udv tuds T T 0 1 V T b uds replace continuous stress/displacement fields by discrete counterparts discrete optimization problem to be solved

22 OPTIMIZATION AND MECHANICS Euler ( ): Since the fabric of the Universe is most perfect and is the work of a most wise Creator, nothing whatsoever takes place in the Universe in which some relation of maximum or minimum does not appear. 22

23 OPTIMIZATION AND MECHANICS Example linear spring: Governing equation: F kx 23

24 OPTIMIZATION AND MECHANICS Example linear spring: Governing equation: F kx Optimization problem: minimize kx Fx

25 OPTIMIZATION AND MECHANICS Example linear spring: Governing equation: F kx Optimization problem: minimize kx Fx Solution: d 1 2 ( kx Fx) 0 kx F 0 dx 2 25

26 VARIATIONAL MECHANICS Identify governing equations Construct optimization problem (variational principle) Discretize in space and time (finite elements/differences) Solve (send problem to black box) 26

27 VARIATIONAL MECHANICS Identify governing equations Construct optimization problem (variational principle) Discretize in space and time (finite elements/differences) Solve (send problem to black box) Examples include: Limit Analysis, Elasticity, Elastoplasticity, Poromechanics, etc 27

28 APPLICATION 1: DESIGN OF SHALLOW FOUNDATION 28

29 APPLICATION 1: DESIGN OF SHALLOW FOUNDATION Procedure: 1a. Determine limit load (UB & LB Exact ) 1b. Factor limit load to get serviceability load 2. Determine deformations under serviceability load and adjust design if necessary 3. Determine full load-displacement curve from zero to collapse (optional) 29

30 APPLICATION 1: DESIGN OF SHALLOW FOUNDATION 30

31 APPLICATION 1: DESIGN OF SHALLOW FOUNDATION 31

32 APPLICATION 1: DESIGN OF SHALLOW FOUNDATION q = 600 kn/m 2 32

33 APPLICATION 1: DESIGN OF SHALLOW FOUNDATION 33

34 APPLICATION 1: DESIGN OF SHALLOW FOUNDATION 34

35 APPLICATION 2: SLOPE SUBJECTED TO UNCONFINED SEEPAGE 35

36 APPLICATION 2: SLOPE SUBJECTED TO UNCONFINED SEEPAGE Tasks: 1a. Determine seepage pressures 1b. Perform strength reduction: 36

37 APPLICATION 2: SLOPE SUBJECTED TO UNCONFINED SEEPAGE 37

38 APPLICATION 2: SLOPE SUBJECTED TO UNCONFINED SEEPAGE 38

39 APPLICATION 2: SLOPE SUBJECTED TO UNCONFINED SEEPAGE 39

40 APPLICATION 3: SLOPE WITH PRE-EXISTING FAULT 40

41 APPLICATION 3: SLOPE WITH PRE-EXISTING FAULT 41

42 APPLICATION 4: ANCHORED SHEET PILE WALL 42

43 APPLICATION 4: ANCHORED SHEET PILE WALL 43

44 APPLICATION 5: EXCAVATION MODEL TEST 44

45 APPLICATION 5: EXCAVATION MODEL TEST 45

46 APPLICATION 5: EXCAVATION MODEL TEST 46

47 APPLICATION 5: EXCAVATION MODEL TEST 47

48 APPLICATION 5: EXCAVATION MODEL TEST 48

49 APPLICATION 5: EXCAVATION MODEL TEST 49

50 APPLICATION 5: EXCAVATION MODEL TEST 50

51 APPLICATION 5: EXCAVATION MODEL TEST 51

52 APPLICATION 5: EXCAVATION MODEL TEST 52

53 APPLICATION 5: EXCAVATION MODEL TEST 53

54 APPLICATION 5: EXCAVATION MODEL TEST 54

55 APPLICATION 5: EXCAVATION MODEL TEST 55

56 APPLICATION 5: EXCAVATION MODEL TEST 56

57 APPLICATION 5: EXCAVATION MODEL TEST 57

58 APPLICATION 5: EXCAVATION MODEL TEST Two analysis with: i) E = E 50 = 20 MPa and ii) E = E ur = 100 MPa 58

59 APPLICATION 5: EXCAVATION MODEL TEST 59

60 APPLICATION 5: EXCAVATION MODEL TEST 60

61 APPLICATION 6: SHEET PILE WALL SUBJECTED TO SEEPAGE PRESSURE 61

62 APPLICATION 6: SHEET PILE WALL SUBJECTED TO SEEPAGE PRESSURE 62

63 APPLICATION 6: SHEET PILE WALL SUBJECTED TO SEEPAGE PRESSURE 63

64 APPLICATION 6: SHEET PILE WALL SUBJECTED TO SEEPAGE PRESSURE 64

65 CONCLUSIONS - New geotechnical finite element software Optum G2 - Complete package for stability and deformation analysis - State-of-the-art calculation core + state-of-the-art human-computer interaction principles = true user-friendliness - Advanced numerical analysis for everyone not just the experts! - Try it out: free download and trial/academic license at: 65

66 CONCLUSIONS - New geotechnical finite element software Optum G2 - Complete package for stability and deformation analysis - State-of-the-art calculation core + state-of-the-art human-computer interaction principles = true user-friendliness - Advanced numerical analysis for everyone not just the experts! - Try it out: free download and trial/academic license at: THANKS FOR YOUR ATTENTION! 66