Design Parameters:

  • Soil Properties:


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.
  • Illustration

    illustration Earth Pressure Distribution Soil Pressures Net force distribution Reinforcement design