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Design table - Terraforce L22 Block

Maximum wall heights (in block height, metres, feet) for a single skin, mass gravity, block retaining wall system - without additional interlocking keys, reinforcements or backfill stabilizing.

Retained Soil Backslope above crest
of retaining wall
Wall inclination from horizontal
  
60° 65° 70° 75° 80° 85° 90° inclination
115.5 93.3 72.8 53.6 35.3 17.5 0 mm setback
4.5 3.7 2.9 2.1 1.4 0.7 0 " setback
Firm clay
&
compact silt
0
 15.3 12.0 9.2 7.3 5.7 4.3 3.1 L22 block rows
3.1 2.4 1.8 1.5 1.1 0.9 0.6 meters
10.02 7.87 6.04 4.79 3.75 2.82 2.06 feet
10°
 12.1 9.7 7.7 5.9 4.5 3.6 2.8 L22 block rows
2.4 1.9 1.5 1.2 0.9 0.7 0.6 meters
7.93 6.37 5.03 3.89 2.93 2.35 1.85 feet
22°
 10.2 7.4 5.1. 3.7 2.8 2.1 1.6 L22 block rows
2.0 1.5 1.0 0.7 0.6 0.4 0.3 meters
6.68 4.87 3.36 2.40 1.86 1.41 1.03 feet
 
Silty sand
&
sand
0°
 23.5 17.7 13.3 10.0 7.7 6.1 4.7 L22 block rows
4.7 3.5 2.7 2.0 1.5 1.2 0.9 meters
15.45 11.62 8.72 6.59 5.06 3.99 3.09 feet
10°
 21.0 15.4 11.3 8.2 6.5 5.0 3.8 L22 block rows
4.2 3.1 2.3 1.6 1.3 1.0 0.8 meters
13.78 10.12 7.38 5.39 4.26 3.29 2.47 feet
22°
 17.8 12.0 8.7 6.4 4.9 3.6 2.8 L22 block rows
3.6 2.4 1.7 1.3 1.0 0.7 0.6 meters
11.69 7.87 5.70 4.19 3.19 2.35 1.85 feet

  1. Wall height measured from top of foundation / levelling pad.
  2. Top of foundation / levelling pad a minimum of 150mm / 0.5 ft below ground level
  3. No allowance made for surcharge above wall
  4. Angle of internal friction used in calculations: P(firm clay)>26°,P(silty sand)>32°.
  5. Compaction effort at optimum moisture content to ensure maximum density achievable.
  6. Provided that groundwater conditions are controlled, a wide variety of soil types can be used for infill soil.
  7. Subsoil drainage is essential to intercept groundwater. Build-up of hydrostatic pressure and seepage forces minimised.
  8. Surface water run-off should be directed away from the wall