Oasys User Group Forum

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Oasys User Group Forum

• Numerical Modelling of
• Soil-structure Interaction Problems
• Hoe Yeow

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Software
In-house Oasys SAFE for 2D problems
Propped excavation
Berm excavation
Tunnel tunnelling
Façade model
Embankment and slope
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SoftwareBP00.1
In-house Oasys LS-Dyna for 3D problems (PC
based)
Car crash
Air bag
Gravity foundation
Tunnelling
Piled raft
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BRICK soil modelState of the art non-linear,
small strain fine grain soil model(Simpson
92)London ClaySingapore Marine ClayFlorence
claysBangkok clays Hong Kong CDG (back
analyses only)
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Why Numerical Modelling? HP000.1

• Design requirements
• Economic design
• Justifying critical design
• Complex problems, evaluating risks
• Investigate failures
• Ground movement damage assessments
• Clients requirements

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Design Requirements
(Potts and Zdravkovic, 1999)
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Economic DesignBP00.1
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Value for money - Batheaston Bypass BP00.1
combined numerical modelling and observation
method
(1998)
page 145 ..

• minimum saving of 860,000

• reduction of excavation programme from 15 months
  to 6 months

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Value for money Canary Wharf Piled Raft BP00.1

• Base grouted bored pile (capacity ? ?m?)
• Raft action to increase mean effective stress
• Savings of 30 in piling cost
• Complex soil-structure interaction

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Justifying critical design and approval BP00.1
Metsovitikos Bridge (original design)
Gravity anchor foundation

• complex ground conditions
• highly 3D
• - slope stability
• - ubiquitous joint model

Tunnelling operation

• complex SCL sequence
• (previously known as NATM)
• large excavation next to existing tunnels

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Ashford Box Design (1.8km cut and cover, 15m
deep)BP00.1

• Non-symmetrical
• Interaction btw. walls
• Permanent under slab drainage system
• Permeability, kh gt kv
• Observation method

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Complex problem, evaluate construction risks and
approval
Deformed shape
RC bored pile, 1.8m diameter
200x magnified
Horizontal displacement
Steel tunnel 3.68m diameter, 0.508m segment
width, 124mm flange thickness
Each element is 0.508m wide, to represent a
segment
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Investigate failureBP00.1
Heathrow Express Tunnel Collapse
Hull tunnel
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Ground Movement Damage AssessmentsBP00.1
Effects on existing tunnels
Britannic House
Excavation
Computed tunnels distortion
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Clients requirements (Florence TAV Station,
Italy)

• Non linear, small strain soil model
• Coupled consolidation
• Compare with pseudo-FE computation

Pseudo-FE FREW
SAFE
Railway loading
Wall
Prop 1
28m
Prop 2
Non-linear soil model
Tension piles