CIVIL ENGINEERING FORMULAS

CONCRETE FORMULAS 151

falls outside the middle third, the pressure vanishes under a zone around the
heel, and pressure at the toe is much larger than for the other cases.
The variables in the five formulas in Fig. 5.4 are

P 1 andP 2 the pressure, lb/ft^2 (MPa), at the locations shown
Landadimensions, ft (m), at the locations shown
Rvthe total downward force on the soil behind the retaining wall, lb (N)
Rresultant, lb(N)

Earth

backfill

Stem

Front

Earth in front Footing or base

Toe

Back

Heel

Heel

K

DC

B

A

Stem

Stem

Toe Toe

T- shape wall

Reversed

L-shape wall

Stem

Stem Stem

L-shape wall

Counterfort wall

Counterfort

Heel

Toe Heel

Toe

Buttress

Buttress

Buttressed wall

(a)

FIGURE 5.4 (a) Six types of retaining walls. (b) Soil-pressure variation in retaining

walls. (Merritt-Building Construction Handbook, McGraw-Hill.)