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Design table - Terraforce L12 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
121 98 76 56 37 18 0 mm setback
4.8 3.9 3 2.2 1.5 0.7 0 " setback
Firm clay
&
compact silt
0
 15.9 12.7 9.9 7.6 5.8 4.4 3.5 L12 block rows
3.3 2.7 2.1 1.6 1.2 0.9 0.7 meters
11.0 8.8 6.8 5.3 4.0 3.0 2.4 feet
10°
 12.7 10.3 8.1 6.2 4.8 3.7 3.0 L12 block rows
2.7 2.2 1.7 1.3 1.0 0.8 0.6 meters
8.8 7.1 5.6 4.3 3.3 2.5 2.1 feet
22°
 10.5 7.8 5.6 4.0 2.7 2.0 1.8 L12 block rows
2.2 1.6 1.2 0.8 0.6 0.4 0.4 meters
7.2 5.4 3.9 2.8 1.9 1.4 1.2 feet
 
Silty sand
&
sand
0°
 24.6 19.0 14.3 10.6 7.9 6.1 5.2 L12 block rows
5.2 4.0 3.0 2.2 1.7 1.3 1.1 meters
16.9 13.1 9.9 7.3 5.4 4.2 3.6 feet
10°
 21.8 16.5 12.2 8.9 6.4 4.9 4.3 L12 block rows
4.6 3.5 2.6 1.9 1.3 1.0 0.9 meters
15.0 11.4 8.4 6.1 4.4 3.4 3.0 feet
22°
 16.9 12.8 9.4 6.8 4.8 3.6 3.2 L12 block rows
3.5 2.7 2.0 1.4 1.0 0.8 0.7 meters
11.6 8.8 6.5 4.7 3.3 2.5 2.2 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