Lateral Earth Pressure€¦ · Lateral earth pressure Surcharge loads Axial loads Wind on...
Transcript of Lateral Earth Pressure€¦ · Lateral earth pressure Surcharge loads Axial loads Wind on...
Lateral Earth Pressure
Loads and Forces Acting on Retaining Wall There are various types of loads and forces acting on retaining wall, which are: Lateral earth pressure Surcharge loads Axial loads Wind on projecting stem Impact forces Seismic earth pressure Seismic wall self-weight forces
Surcharge loads acting on retaining wall are additional vertical loads that are used to the backfill soil above the top of the wall. It can be either dead loads for example sloping backfill above the wall height or live load which could result from highway or parking lot, paving or adjacent footing.
Effective stress (σ‘) Total Normal Stress (σ) Pore Water Pressure (u)
σ
σ
σ‘
Defined as soil stress which not influenced by water pressure in soil body.
sat
sat sub
• σ
Vertical pressure
Lateral pressure
σh/ σv
• 1) At-rest : Soils in nature have an in-situ state of stress. This "in-situ" state of stress is commonly referred to as "At-rest" conditions.
• If a natural surface is level and all stratigraphy is also level, then the "At-rest" state of stress can be described by two main stresses:
a) The vertical stress [σv](effective stress (σ’) and total stress (σ))
b) The horizontal stress[σH]
σv
σH
1)At – rest condition
K0 = σH/ σV
• All effective horizontal stresses are
• K0 = coefficient of lateral pressure.
• σ V = effective vertical stress
• For "At-rest" conditions, coefficient of lateral pressure is :
V …Lateral earth pressure is function of vertical stress
At – rest condition
• If a stiff gravity wall fully bears on bedrock, in such a condition a retaining wall will essentially feel the full "At-rest" driving soil pressures.
Soil element
σv = Ꝩz
2) Active earth pressure • Soil pressure that is trying to move the structure
Soil expands by an amount ΔH
3) Passive earth pressure
Soil compresses by an amount ΔH
p
+
-
+
p p
Refer notes and problems solved in class