Page 362 - Masonry and Concrete

Retaining Walls
361
RETAINING WALLS

A Maximum exposed wall height (feet).

Soil Angle of Internal Friction Soil Angle of Internal
(Table B) 28° Friction (Table B) 34°

Unit Wall Wall Wall Wall Wall Wall
Height, battered battered battered battered battered battered
Inches 5° 10° 15° 5° 0° 15°
6 2'-0" 2'-6" 3'-0" 2'-6" 3'-6" 3'-6"
8 2'-3" 2'-3" 2'-10" 2'-10" 3'-6" 3'-6"
Notes: Backfill slope at top of wall is zero, surcharge load is zero, required wall embedment at
toe is 6 inches, soil and block unit weight is 120 pcf, unit depth is 12 inches. Wall batter is for
unit setback per course.

B Angle of internal friction for various soil types.
Angle of Internal
Soil Type Friction, Degrees
GW Well-graded gravels, gravel sand mixtures, little or no fines 37-42
GP Poorly graded gravels or gravel sand mixtures, little or no fines
SW Well-graded sands, gravelly sands, little or no fines 33–40
SP Poorly graded sands or gravelly sands, little or no fines
GM Silty gravels, gravel-sand-silt mixtures
SM Silty sand, sand-silt mixtures 28–35
GC Clayey gravels, gravel-sand-clay mixtures
SC Clayey sands, sand-clay mixture
ML Inorganic silts and very fine sands, rock flour, silty or clayey
fine sands or clayey silts with slight plasticity 25–32
CL Inorganic clays of low to medium plasticity, gravelly clays,
sandy clays, silty clays, lean clays

FIGURE 10-17
Maximum exposed height for conventional SRWs based on soil type and angle of wall batter. (from National
Concrete Masonry Association, Design Manual for Segmental Retaining Walls, NCMA, Herndon, VA).

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