## Thursday, March 23, 2017

### Different types of Loads and Forces functioning on Retaining Wall

Retaining wall design will contain any or all of loads and forces which are briefly described in the following sections:
1. Lateral earth pressure
4. Wind on projecting stem
5. Impact forces
6. Seismic earth pressure
7. Seismic wall self-weight forces
1. Lateral Earth Pressure Functioning on Retaining Wall
The primary objective of developing a retaining wall is to hold the soil. For this reason, soil lateral earth pressure is a vital factor in the design. Among various theories, sliding soil wedge theory is mostly recognized for measuring the lateral earth pressure.
The wedge theory implies that a triangular wedge of soil will fall down if retaining wall is disconnected unexpectedly and the wall has to withstand this wedge soil. From the Figure 1, we can view free body lateral forces performing on retaining walls.
Coulomb and Rankine equations belong to most vital formulas which are used to compute lateral earth pressure:
The Coulomb method of Lateral Earth Pressure Calculation
This equation considers backfill slope, friction angle at wall face, rupture plan angle, and internal friction angle etc.
Where:
Ka : coefficient of active pressure
: Angle of internal friction
: Angle of backfill slope
: Angle of friction among soil and wall (2?3Angle of internal friction to 1?2Angle of internal friction is supposed)
: Slope angle of the wall that is calculated from horizontal (same as 90 degree for vertical wall)
Besides, concerning flat level backfill soil, observing zero friction at soil-wall interface, and soil-sidewall is vertical, the coulomb equation is contracted to the following: