Basic Principles of retaining wall design Flashcards
What is required for large-scale mass movements?
Slope stability analysis
Why might retaining structures not be used in large-scale mass movements?
They may be too expensive.
What may be needed instead of retaining structures for large-scale mass movements?
Alternative stabilization methods or monitoring systems.
What characterizes a rockfall?
Hard or consolidated material, like clay with large boulders.
What is a topple in geology?
A block of rock creating a fracture that propagates downwards.
What happens in a rotational landslide?
Shear failure causing a slump to a more stable configuration.
What defines a translational landslide?
Movement along a weak plane, often where material changes occur.
What is a block slide?
Material flows as a block with both translation and rotation
What is unique about a lateral slide?
Material moves sideways on a firm clay base without gravity’s full effect.
How is mass movement different on a small scale?
Contained within a small area, with retaining structures usually sufficient for stabilization.
What are tailings in mining?
Pulverized rock mixed with chemicals, creating a toxic slurry.
Why are tailing dams considered unstable?
They’re built with small dikes that can be breached by water pressure.
What are two purposes of retaining structures?
To create space (temporary or permanent) and stabilize soil or slopes and excavations.
What is a Serviceability Limit State (SLS) in retaining structures
A state where deformation leads to ground loss or infrastructure damage.
What are the four primary concerns in retaining structure design?
Bearing capacity, sliding, overturning, and general instability
How does a gravity wall provide stability?
Through its self-weight
What’s notable about cantilever retaining walls?
They’re slender and economical, commonly used in urban areas but prone to deformation.
How does a tieback wall increase stability?
Through soil nails that add strength.
What is the purpose of bracing in excavations?
To prevent wall deformation.
How can the surface of retaining walls enhance stability?
With rough textures or patterns to increase friction.
What is the primary resistance mechanism of a cantilever wall?
Wall embedment into the foundation soil.
What distinguishes a tieback wall?
It borrows resistance from soil behind the wall using tiebacks.
What is the purpose of bracing in a braced excavation?
To prevent deformation by providing additional stiff elements.
How are soil nails used in slope stabilization?
Installed in natural soil, they extend beyond the potential slip plane for reinforcement.
What are geotextiles and how are they used in retaining walls?
Made of PVC, used for economical and sustainable wall reinforcement.
In terms of soil-structure interaction, what are the soil conditions to consider?
At-rest, active, and passive soil pressures.
What is K_0 in soil mechanics?
At-rest lateral earth pressure coefficient.
What state occurs when a wall moves away from the soil?
Active state.
What is the formula for active earth pressure coefficient (k_A )?
k _A =1−sin(ϕ)/(1+sin(ϕ)).
In which state is the soil being pushed by the wall?
Passive state.
What’s the relationship between
k_A and k_P (passive earth pressure coefficient)?
k _A=1/k _P
What is OCR in the context of
K_0?
Over-consolidation ratio.
How do earth pressure coefficients rank?
k _p >k _0 >k_a
What is the formula for effective horizontal stress (σ’_H) in soils?
σH′=Kσ_v′in hydrostatic conditions without shear resistance.
What are the assumptions of Rankine’s design method for retaining walls?
The wall is vertical, frictionless against soil, in a horizontal, dry soil surface, rigid, and the soil is loose and in an at-rest state.