Soft ground tunnel design

Cover
Half title
Title page
Copyright Page
Contents
Preface
Books on tunnel construction methods
Acknowledgements
Author
1. Real tunnel behaviour
	1.1. In situ stress states
	1.2. Overview of tunnel behaviour
		1.2.1. Undrained soil behaviour
		1.2.2. Drained soil behaviour
	1.3. Movements of the ground surface
		1.3.1. Transverse vertical settlements
		1.3.2. Transient settlements
		1.3.3. Horizontal surface movements
		1.3.4. Long-term settlements
	1.4. Subsurface ground movements
	1.5. Stability
		1.5.1. The consequences of instability
		1.5.2. The causes of instability
	1.6. Tunnel lining movements
		1.6.1. Case studies of tunnel lining movements
	1.7. Tunnel lining stresses
		1.7.1. How do tunnel lining stresses develop over time?
		1.7.2. Design based on precedent practice
		1.7.3. Heathrow Express Terminal 4 Station concourse tunnel case study
	1.8. Summary
	References
2. Undrained stability
	2.1. Overview of stability theory
	2.2. Undrained stability
		2.2.1. Heading stability in homogeneous clay
		2.2.2. Heading stability in clay with undrained shear strength increasing with depth
		2.2.3. Heading stability in clay with overlying coarse-grained soils
		2.2.4. Numerical modelling of heading stability in clay
		2.2.5. Summary of undrained stability
	2.3. Blow-out failure in clay
		2.3.1. Softening and erosion
		2.3.2. Hydraulic fracturing in clay
		2.3.3. Passive failure in clay
		2.3.4. Uplift failure of a tunnel heading invert in clay
		2.3.5. Summary of undrained blow-out failure
	2.4. Problems
	References
3. Drained stability
	3.1. Drained stability without seepage
		3.1.1. Dry cohesionless soils
		3.1.2. Dry drained soils with cohesion
		3.1.3. Comparison of analytical methods with centrifuge tests and finite element models
		3.1.4. Summary of drained stability theory
	3.2. Application of drained stability to closed-face TBMs
		3.2.1. Application to slurry TBMs
		3.2.2. Slurry infiltration during TBM standstills
		3.2.3. Slurry infiltration during excavation
		3.2.4. Application to earth pressure balance TBMs
	3.3. Blow-out failure in drained soils
		3.3.1. Passive failure in drained soils
		3.3.2. Blow-outs caused by hydraulic fracturing
		3.3.3. Summary of blow-outs in drained soils
	3.4. Piping
	3.5. Problems
	References
4. Stability of shafts
	4.1. Hydraulic failure in a shaft during excavation
	4.2. Base heave failure of a shaft in clay
	4.3. Uplift failure in a shaft during excavation
		4.3.1. Verification of the uplift ultimate limit state using Eurocode 7
		4.3.2. Geometry of uplift failure during excavation
	4.4. Uplift failure of a shaft after base slab construction
	4.5. Long-term heave under a shaft base slab
	4.6. Summary of shaft stability
	4.7. Problems
	References
5. Stability and Eurocode 7
	5.1. Size of the zone of ground governing the occurrence of the limit state
	5.2. Correcting for confidence in the site investigation
	5.3. Modelling spatial variability of soil parameters explicitly
	5.4. Applying partial factors
	References
6. Global design using analytical solutions
	6.1. Simple wished-in-place equilibrium
	6.2. Empirical methods
	6.3. Soil-structure interaction using the Curtis-Muir Wood solution
		6.3.1. Notation used in the Curtis-Muir Wood solution
		6.3.2. Boundary conditions and ground
stresses
		6.3.3. Elliptical deformation of a circular
opening
		6.3.4. Elliptical deformation of a thin
inextensible lining
		6.3.5. ‘Full slip’ – no shear between
lining and ground
		6.3.6. ‘No slip’ – full shear interaction
between lining and ground
		6.3.7. Direct compression of the lining
due to uniform load
	6.4. Global design of shafts
	6.5. Bedded beam models
	6.6. Summary
	6.7. Problems
	References
7. Global design using numerical modelling
	7.1. Boundary conditions at the tunnel perimeter
		7.1.1. Wished-in-place tunnel lining
		7.1.2. The convergence-confinement method
			7.1.2.1. The β-factor method
			7.1.2.2. The target volume loss method
		7.1.3. Gap method
		7.1.4. The grout pressure method
		7.1.5. Surface contraction
		7.1.6. Core softening
		7.1.7. Summary
	7.2. Boundary conditions at the edges of the model
	7.3. Boundary distances
	7.4. Element types for the lining and the ground
	7.5. Mesh density and refinement
	7.6. Modelling groundwater
		7.6.1. Undrained behaviour
		7.6.2. Long-term effects
	7.7. Validation and error checking
		7.7.1. Comparison with an analytical solution
		7.7.2. Validation by comparison with a laboratory test or experiment
		7.7.3. Validation by comparison with a case history
	7.8. Constitutive models
	7.9. Interpretation and presentation of results
	7.10. 3D numerical analysis
		7.10.1. Modelling an advancing tunnel in 3D
		7.10.2. Modelling the tunnel lining
		7.10.3. Modelling junctions
			7.10.3.1. Kirsch solution
			7.10.3.2. Wished-in-place 3D numerical
model
			7.10.3.3. 3D numerical model with
sequential construction
	7.11. Summary
	7.12. Problems
	References
8. Lining materials
	8.1. Reinforced concrete
	8.2. Steel fibre-reinforced concrete
		8.2.1. Codes of practice and sources of design guidance
		8.2.2. Material behaviour
		8.2.3. Design assisted by testing
		8.2.4. Determination of characteristic strength values
		8.2.5. Determination of the characteristic
mean strength values
		8.2.6. Durability
		8.2.7. Watertightness
		8.2.8. Fire resistance
	8.3. Concrete reinforced with other fibres
	8.4. Plain concrete
	8.5. Cast iron
	8.6. Summary
	References
9. Segmental lining design
	9.1. Taking account of the effect of joints
in 2D plane strain analyses
	9.2. Rotational rigidity – flat joints
		9.2.1. Linear elastic packers
		9.2.2. Nonlinear packers
		9.2.3. Comparison of different packer types
	9.3. Estimating local forces due to joint rotation
		9.3.1. Calculating joint rotation from
a specified ovalisation
		9.3.2. Using eccentricity of hoop force
to check joint capacity in crushing
and shear
	9.4. Bursting stresses
	9.5. Curved joints
	9.6. Modelling joints in bedded beam analyses
	9.7. Modelling joints in 2D or 3D numerical analysis
	9.8. In service loads – ultimate limit state design
		9.8.1. Application of partial factors to the lining
forces
		9.8.2. Constructing a moment-axial
force interaction diagram
		9.8.3. Design for shear
	9.9. In service loads - serviceability limit state design
		9.9.1. Estimating crack widths
		9.9.2. Constructing a moment-axial force
interaction diagram for the SLS
	9.10. Summary
	9.11. Problems
	References
10. Segment design for transient loads
	10.1. Demoulding
	10.2. Storage
		10.2.1. Actions
		10.2.2. SFRC segment ultimate limit state
design for bending moment
		10.2.3. SFRC segment ULS design for shear force
		10.2.4. SFRC segment SLS design
	10.3. Transportation and handling
	10.4. Erection
	10.5. Installation loads
		10.5.1. Temporary TBM jacking loads
		10.5.2. Longitudinal effects of TBM jacking loads
		10.5.3. Grout pressures and tailseal brushes
		10.5.4. Design for permanent effects of installation
loads
	10.6. Gasket compression and bolt loads
	10.7. Summary
	10.8. Problems
	References
11. Sprayed concrete lining design
	11.1. Primary and secondary linings
		11.1.1. Single-pass lining
		11.1.2. Single-shell lining
		11.1.3. Traditional approach
		11.1.4. Double-shell lining system
		11.1.5. Composite shell lining system
		11.1.6. Initial layer
		11.1.7. Regulating layer
		11.1.8. Finishing layer
	11.2. Designing the profile
		11.2.1. Three arc profile
		11.2.2. Two arc profiles
		11.2.3. Other profile shapes
		11.2.4. Optimising the profile
	11.3. Dividing the face
		11.3.1. Full-face excavation
		11.3.2. Top heading–invert (TH-I) excavation
		11.3.3. Top heading–bench–invert (TH-B-I)
excavation
		11.3.4. Single sidewall drift and enlargement
		11.3.5. Twin sidewall drift and enlargement
		11.3.6. Pilot tunnels
		11.3.7. Binocular caverns
		11.3.8. Trinocular caverns
	11.4. Toolbox measures
		11.4.1. Pocket excavation
		11.4.2. Reduction of advance length
or ring closure distance
		11.4.3. Ground improvement
		11.4.4. Support ahead of the face
		11.4.5. Face dowels
		11.4.6. Dewatering/depressurisation
	11.5. Construction details and tolerances
		11.5.1. Circumferential construction joints
		11.5.2. Radial construction joints
		11.5.3. Tolerances
	11.6. 3D numerical modelling
		11.6.1. Linear elastic sprayed concrete constitutive
model
		11.6.2. Ageing sprayed concrete properties
		11.6.3. Linear elastic – perfectly plastic sprayed
concrete constitutive model
		11.6.4. More complex constitutive models
	11.7. 2D numerical modelling
	11.8. Summary
	11.9. Problems
	References
12. Estimating ground movements
	12.1. Transverse surface settlements
	12.2. Estimating volume loss
		12.2.1. Estimating short-term volume loss
in stiff clays
		12.2.2. Estimating volume loss in other
soil types
	12.3. Longitudinal and transient surface settlements
	12.4. Long-term ground movements
		12.4.1. Long-term ground movements
due to excess pore pressures
		12.4.2. Long-term ground movements due to
the tunnel lining acting as a drain
	12.5. Subsurface ground movements
		12.5.1. Subsurface ground movements
in undrained soils
		12.5.2. Subsurface ground movements
in drained soils
	13.6. Horizontal ground movements
	12.7. Strains in the ground
	12.8. Ground movements due to shaft construction
	12.9. Summary
	12.10. Problems
	References
13. Estimating building damage
	13.1. Stage 1 assessment
	13.2. Stage 2 assessment
		13.2.1. Generic Stage 2 assessment
	13.3. Stage 2b assessment
		13.3.1. Buildings with discrete pad foundations
		13.3.2. Steel or reinforced concrete frame
buildings
	13.4. Stage 3 assessment
		13.4.1. Tunnel excavation
		13.4.2. Soil-structure interaction
		13.4.3. Modelling the building
	13.5. Summary
	13.6. Problems
	References
Appendix A: Derivation of wedge-prism method
	Finding the vertical pressure on surface CDEF
	Finding the sliding friction on surfaces ADE and BCF
	Finding the sliding friction on ABEF
	Calculating values for the F0 nomogram
	Calculating values for the F1 nomogram
	References
Appendix B: Details from derivation of Curtis–Muir
Wood equations
	Integration by parts
Appendix C: Derivation of the deflection of a rectangular
simply-supported beam under a point load
	Bending deflection
	Shear stress
	Unit load method to calculate shear deflection - part 1
	Form factor for shear for a rectangular section
	Unit load method to calculate shear deflection - part 2
	Comparison with Burland & Wroth (1974) equation
	The effect of varying E/G ratio
	References
Index