Tunnel Face Stability & New CPT Applications - Geo-Engineering

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16 2. Stability Analysis of the Tunnel FaceYearSoil conditions aPubl. Author ϕ c p 3D ml. Description Main Equation1961 Horn + + − + − Linear wedge –(( ))1966 Murayama + + + − − Log spiral s min = 12R l pG l G + q w w 1 (l w + w 12 ) − c rd 2 − r2 a2 tan ϕwedge1967 Broms & Bennermark − + − + − Empirical s min = γ (C + R) + q s − N c u , N ≈ 61977 Atkinson & Potts + − − + − Cavity s min = 2K pKp 2−1γ R, K p = 1+sin ϕ1−sin ϕ1980 Davis et al. − + − + − Long wall,upper bound1987 Krause + + − − − Half sphere s min = 1tan ϕHalf circle s min = 11Quarter circle s min = 1tan ϕH = ∫∫ As min = γ (C + R) − 4c u ln ( CR + 1) + q s( )19 D γ ′ − 1 2 π c( )12 +tan ϕ 6 D γ ′ − 1 2( π )c13 D γ ′ − 1 2 π c1988 Mohkam + + + + − Variationalh [w(x, y), θ(x, y), σ(x, y)] dx dy = 0analysis1990 Leca & Dormieux + + − + − Conical bodies s min = N s + ( N s + N γ − 1 ) c ′tan ϕ ′1991 Mori − + + − − Empirical s work = σ 3 − s cutter1994 Jancsecz & Steiner + + − + − Wedge s min = K a3D σ v ′ + p1994 Anagnostou & Kovári + + + + − Wedge, staticinfiltration1999 Belter et al. + + + − + Wedge, layeredsoil columna Model can/cannot (+/−) deal with: ϕ = frictional material model; c = cohesive material model; p = pore pressures; ml. = multiple soil layers;3D = model includes three-dimensional effects.Table 2.1: Overview of stability models
2.1. Introduction 17N Deformation< 1 Negligible1 − 2 Elastic2 − 4 Elasto-plastic4 − 6 Plastic> 6 CollapseTable 2.2: Relation between stability ratio and deformationηη2211001 2C/D015 10k h /k v‘dry’ casewater-saturated soilFigure 2.15: Face stability safety factor for an 8m diameter tunnel as function of relative overburdenand as function of the ratio of horizontal over vertical permeability [52]a certain project and are hardly adaptable for general cases. An exception is the model reportedby Buhan et al. [52]. They describe the framework for a three-dimensional finite element modelof the face of an EPB machine, where the drag forces of seepage flow towards the face havebeen included. This model is applied to an 8m diameter tunnel, and the influence of varyingoverburdens on stability has been studied (see figure 2.15). They also find that the stability safetyfactor depends solely on the ratio of horizontal to vertical permeability k h /k v and not on theirindividual magnitudes.2.1.3 Loss of Support MediumWhen a (sudden) loss of the support medium in the working chamber takes place, and the supportmedium is not or not adequately replenished, the pressure at the face will drop. If the supportpressure decreases, this in turn may lead to active global collapse of the face. The instigation ofthis kind of failure is a high support pressure. Such failures are often categorised as blow-outs,but encompass the classical blow-out as well as several other mechanisms. These will be listedin the following section.First we will deal with the classical blow-out, the lifting of a soil body by a high supportpressure and the subsequent sudden loss of the support medium. The model which yields thelowest maximal allowable support pressure assumes the lifting of the soil over a fairly largeregion. This may occur when the support medium infiltrates the soil, for example in a slurryshield when no filter cake is present at the face. In that case friction of the lifted soil body with
Page 1: Tunnel Face Stability&New CPT Appli
Page 4 and 5: Dit proefschrift is goedgekeurd doo
Page 6 and 7: viAcknowledgementsKolla här, min
Page 8 and 9: viiiAbstractThe tunnel wound on and
Page 10 and 11: xContents3.2.4 Finite Element Model
Page 12 and 13: xiiList of Symbols× ij i = j norma
Page 14: xivList of Symbolsλfirst Lamé con
Page 17 and 18: 1.2. Outline of this Thesis 3suppor
Page 19 and 20: Chapter 2Stability Analysis of the
Page 21 and 22: 2.1. Introduction 7fluidsoilzs Fα
Page 23 and 24: 2.1. Introduction 9Figure 2.3: Unsu
Page 25 and 26: 2.1. Introduction 11q sq sq sααα
Page 27 and 28: φ = 40 ◦φ = 35 ◦2.1. Introduc
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Page 33 and 34: 2.1. Introduction 19GC45 ◦ + φ/2
Page 35 and 36: 2.1. Introduction 21Figure 2.19: Ce
Page 37 and 38: 2.1. Introduction 23Figure 2.21: In
Page 39 and 40: 2.1. Introduction 25D (m) Soil type
Page 41 and 42: 2.2. Wedge Stability Model 27the su
Page 43 and 44: 2.2. Wedge Stability Model 29xyhz =
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Page 51 and 52: 2.2. Wedge Stability Model 37with a
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Page 55 and 56: 2.2. Wedge Stability Model 41∆p f
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Page 59 and 60: 2.2. Wedge Stability Model 45from t
Page 61 and 62: 2.2. Wedge Stability Model 47γF(t/
Page 63 and 64: 2.2. Wedge Stability Model 49s min
Page 65 and 66: 2.2. Wedge Stability Model 5140∆s
Page 67 and 68: 2.3. Model Sensitivity Analysis 53P
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2.4. Comparison with Field Cases 67
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Figure 2.57: Overview of soil strat
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2.5. Further Groundwater Influences
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2.6. Conclusions 97the effective st
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2.6. Conclusions 99has been made th
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Chapter 3Horizontal Cone Penetratio
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3.2. Interpretation of Cone Penetra
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3.3. Calibration Chamber Tests on S
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3.4. Scale Model Tests 129Figure 3.
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3.4. Scale Model Tests 1315210Figur
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3.5. Field Tests 133Figure 3.35: Pl
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3.6. Modelling Horizontal Cone Pene
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3.7. Conclusions 141W H/V 043Ticino
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Chapter 4High-Speed Piezocone Tests
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4.2. Determination of Liquefaction
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4.2. Determination of Liquefaction
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4.4. Calibration Chamber Tests 149
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4.4. Calibration Chamber Tests 1518
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4.4. Calibration Chamber Tests 153v
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4.4. Calibration Chamber Tests 155-
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4.5. Conclusions and Recommendation
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4.5. Conclusions and Recommendation
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Chapter 5Conclusions and Recommenda
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5. Conclusions and Recommendations
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Bibliography[1] M.Y. Abu-Farsakh, G
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Bibliography 167[30] B. Belter, W.
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Bibliography 169[65] J.K. van Deen.
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Bibliography 171[99] E. Kreyszig. A
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Bibliography 173[133] Committee on
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Bibliography 175[171] F.W.J. van Vl
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Curriculum VitaeWout Broere was bor
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SamenvattingGraaffrontstabiliteit &
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Samenvatting 181spanningen ook in d
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NawoordIn de afgelopen jaren heb ik
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Appendix ABasic Equations of Ground
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A.1. Semi-confined System of Aquife
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A.2. Transient Flow 189withS s the
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....Appendix BBasic Equations of El
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B. Basic Equations of Elasticity 19
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