Modelling of Tunnels in 2D & 3D

Transcription

1 MIDAS Geotechnical Know-how Sharing Series November 28 th, 2017 (Tue) 10:00 ~ 11:00 AM (CET) Session 3. Modelling of Tunnels in 2D & 3D JaeSeok Yang Principal Geotechnical Engineer, MIDAS IT Integrated Solver Optimized for the next generation 64-bit platform Finite Element Solutions for Geotechnical Engineering

2 01 Tunnel Construction 02 Simulation of the Sequential Excavation 03 Case Study 04 Conclusion Integrated Solver Optimized for the next generation 64-bit platform Finite Element Solutions for Geotechnical Engineering

3 Tunnel Construction Most common tunnel excavation techniques Open faced shield tunnelling Tunnel Boring Machines (TBM), including slurry shield and Earth Pressure Balance (EPB) tunnelling The sprayed concrete lining (SCL) method 3

4 Tunnel Construction Open faced shield tunnelling Schematic view of shielding during tunnel excavation 4

5 Tunnel Construction Tunnel Boring Machines (TBM) Schematic view of TBM 5

6 Tunnel Construction Sprayed concrete lining (SCL) method Schematic view of SCL method 6

7 Tunnel Construction Ground response to tunnel construction Sources of volume loss (example of TBM) 7

8 01 Tunnel Construction 02 Simulation of the Sequential Excavation 03 Case Study 04 Conclusion Integrated Solver Optimized for the next generation 64-bit platform Finite Element Solutions for Geotechnical Engineering

9 Simulation of the Sequential Excavation Introduction Axi-symmetric geometry Plane strain geometry 9

10 Simulation of the Sequential Excavation Modelling of tunnels in 3D 3D stress transfer at tunnel face 10

11 Simulation of the Sequential Excavation Setting up the initial conditions If it is known: Modelling the complete geological history of the site If it is not known: Input the conditions appropriate to a greenfield site (by means of the material unit weight, the pore water pressure profile and the coefficient of earth pressure at rest, K 0 ) Simulating any previous construction activities that have occurred at the site 11

12 Simulation of the Sequential Excavation Important boundary conditions The boundary displacement conditions, required to represent the far field conditions or any symmetry of the problem Any surface traction The excavation of solid soil elements The construction of structural shell elements The hydraulic conditions at the far field boundaries, the soil strata interfaces (if an interface is between consolidating and non-consolidating elements) and the tunnel lining itself 12

13 Simulation of the Sequential Excavation Gap method Gap method for modelling tunnel excavation 13

14 Simulation of the Sequential Excavation Contraction Engineering example: Contraction of shield TBM 14

15 Simulation of the Sequential Excavation Convergence-confinement method Convergence-confinement method 15

16 Simulation of the Sequential Excavation Modelling tunnel excavation Transient Seepage Analysis Control Drag & Drop Tree Structure Initial & Construction Excavation Load Distribution Factors 16

17 Simulation of the Sequential Excavation Progressive softening method Progressive softening method 17

18 Simulation of the Sequential Excavation Volume loss control method Volume loss method 18

19 Simulation of the Sequential Excavation Modelling tunnel lining The use of solid elements Allows the analyst a very wide range of constitutive models Maintain an acceptable element shape (defined by the aspect ratio of length to width) The use of shell elements Removes the problem of aspect ratio control Allows more flexibility in the mesh definition A structural nature (i.e. shear force, hoop force, and bending moment) 19

20 Simulation of the Sequential Excavation Gauging element Gauging Element Generation Gauging Element Results 20

21 Simulation of the Sequential Excavation Modelling the connections between lining segments Modelling segment connection as a moment-free joint Unrolled and rolled tunnel lining 21

22 Simulation of the Sequential Excavation Shell interface element Input properties of the shell interface element Input dialog for user-defined shell interface behaviour 22

23 Simulation of the Sequential Excavation Shell interface element Example of shell interface element creation 23

24 01 Tunnel Construction 02 Simulation of the Sequential Excavation 03 Case Study 04 Conclusion Integrated Solver Optimized for the next generation 64-bit platform Finite Element Solutions for Geotechnical Engineering

25 Introduction - Two single tracks (TBM diameter Ø 5.8m), total length of 15.5km - Totally automatic, driverless, lightweight rail system 17 Underground Stations Total travel time: 23 min Maximum depth ~ 35m Completed in

26 Introduction - Two single tracks (TBM diameter Ø 5.8m), total length of 15.5km - Totally automatic, driverless, lightweight rail system 26

27 Introduction 27

28 Description of sites and its specifics Copenhagen Central Station 28

29 Description of sites and its specifics Kongens Nytorv Station Magasin Du Nord 29

30 Description of sites and its specifics Magasin Du Nord 30

31 Description of sites and its specifics Magasin Du Nord 31

32 Description of sites and its specifics Sand till Limestone Magasin Du Nord 32

33 Description of sites and its specifics 1930 s basement and ground floor 1960 s first floor and above 1960 s colonned r.c. costr r.c. constr Concrete encased steel costr Mansory construction 1962 R.C.. car park Main 1893 Magasin building Medieval Part Early 20th century 1990 s r.c. construction 33

34 Description of sites and its specifics Tunnel 1 alignment Tunnel 2 alignment 34

35 Geotechnical Characterization Tunnel 1 35

36 Geotechnical Characterization Tunnel 2 36

37 Geotechnical Characterization Nomenclature Layer No. FY Age Deposition environment Soil type Recent Re Fi/Ts Fill PG2 Postglacial Pg Ma Gravel Solifluction/meltwater clay, silt and SL/SI/SS Lateglacial Lg Ss/Mw sand Quaternary ML1/MS1 Gl Upper clay and sand till DS2/DG2 Mw Middle meltwater sand and gravel Glacial Gc ML2/MS2 Gl Lower clay and sand till DS3/DG3 Mw Lower meltwater sand and gravel UCL Upper Copenhagen Limestone MCL Palaeogene Danian Da Ma Middle Copenhagen Limestone LCL Lower Copenhagen Limestone Nomenclature Layer No. Model γ sat [kn/m 3 ] ф c [kpa] K 0 E [MPa] FY EL DS / DG / MS MC /100 * 0.25 UCL (HP) MC UCL / MCL MC Input parameters in modelling v 37

38 Definition of objectives Input Evaluation of the class of damage that the structure may bring back Identification of the characteristics of the materials of the structural elements Calibration of the rigidity of the structural elements Definition of permanent and accidental loads on the existing structure Discretization of the coupled ground-structure model for interaction analysis (fully coupled soil-structure interaction analysis) Tunnel steps and sequences Output Evaluation of structural stress under ordinary conditions Evaluation of absolute and differential settlements during tunnel excavation sequences Evaluation of structural stresses during the tunnel excavation sequence and comparison with stresses under ordinary conditions Evaluation of the class of damage and comparison with the allowable damage class Determination of threshold levels Finding any mitigation actions Check in with the monitoring data 38

39 Modelling Geometry of the structure model - First floor 39

40 Modelling Geometry of the structure model - Type plane 40

41 Modelling Numerical model of 3D structure 41

42 Modelling Material Modulus of Elasticity Weight density Masonry 1500 MPa 18 kn/m 3 Cast Iron MPa 73 kn/m 3 Wrought Iron MPa 75 kn/m 3 Concrete C25/30 Concrete C25/30 floor MPa 25 kn/m MPa 25 kn/m 3 Steel S MPa 78.5 kn/m 3 Concrete encased steel columns Composite section: Steel S275 +concrete C25/30 Composite section: Steel S275 +concrete C25/30 Numerical model of 3D structure 42

43 Modelling Numerical model of 3D structure - Solicitations in cond. ordinary 43

44 Modelling Numerical model of 3D structure - Solicitations in cond. ordinary 44

45 Modelling Numerical model of 3D fully coupled soil-structure interaction 45

46 Modelling Numerical model of 3D fully coupled soil-structure interaction 46

47 Modelling Numerical model of 3D fully coupled soil-structure interaction 47

48 Modelling Numerical model of 3D fully coupled soil-structure interaction 48

49 Modelling Numerical model of 3D fully coupled soil-structure interaction 49

50 Modelling Numerical model of 3D fully coupled soil-structure interaction 50

51 Modelling Applied load conditions 51

52 Modelling TBM construction phases 52

53 Modelling TBM construction phases 53

54 Modelling TBM EPB face pressure Face pressure TBM construction phases 54

55 Modelling TBM construction phases 55

56 Modelling Lining TBM construction phases 56

57 Modelling Shield Face pressure Lining Jack pressure Lining Solid grouting Lining + Solid grouting Steel Shield Face pressure TBM construction phases 57

58 Modelling TBM construction phases 58

59 Analysis implemented scenarios and details For each scenario, you have been determined: cuts (absolute and differential) stress on structures level of potential damage c (%) DR [cm] V loss (%) SC 3 E SC 4 - E SC 3 E SC 4 E

60 Case Study Results and final considerations Evolution of the settlement 60

61 Results and final considerations Deformation of the structure 61

62 Settlement of scenario 4-E2, V loss 1% 62

63 Results and final considerations Settlement of scenario 3-E2, V loss 0.5% Settlement of scenario 4-E2, V loss 1% 63

64 01 Tunnel Construction 02 Simulation of the Sequential Excavation 03 Case Study 04 Conclusion Integrated Solver Optimized for the next generation 64-bit platform Finite Element Solutions for Geotechnical Engineering

65 Conclusion Summary A three dimensional engineering process Methods of simulating tunnel construction in plane strain: the volume loss to be expected; the percentage of load removal prior to lining construction; or the actual displacement of the tunnel boundary Segmental linings to open or rotate at their joints, or sprayed concrete linings to crack View any prediction of intermediate and long term behaviour Select constitutive models capable of reproducing field behaviour FEM can be used to quickly assess the impact of different influences on tunnelling-induced ground movements Numerical analysis can incorporate adjacent influences 65

66 Q & A 66