Height of earth retained
Symbol: h
Unit: m
Expected value: design is economical for less than 10 m height of earth.
It is the difference between the level of earth on either side of the wall.
Surcharge pressure
Symbol: ws
Unit: kN/m2
Expected value: can be 0
Gravity loads acting on backfill due to the construction of buildings or the movement of vehicles near the top of the retaining wall
These loads are considered as uniformly distributed loads, and are mostly present on a level backfill.
Angle of internal friction of soil
Symbol: φ
Unit: degree (°)
Expected value: 20 - 40°
Cohessionless granular soil has been considered in this design.
Slope of backfill
Symbol: β
Unit: degree (°)
Expected value: 0-35°
It is the angle made by backfill soil with the horizontal.
Unit weight of soil
Symbol: γSoil, γe
Unit: kN/m3
Expected value: 14-22 kN/m3
Unit weight of soil varies from 14 kN/m3 for clay to 22 kN/m3 for gravels.
Soil-wall interface frictiion
Symbol: δ
Unit: degree (°)
Expected value: 10-30°
The wall friction has been neglected in the analysis, but it is required for calculation of sliding factor of safety for the wall.
The typical value of wall friction is 2/3 to 3/4φ between granular soil and concrete wall.
Unit weight of concrete
Symbol: γconcrete, γc
Unit: kN/m3
Expected value: 23-25 kN/m3
Unit weight of concrete is usually taken as 24 kN/m3.
