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Design table - Terraforce L11 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
129.9 104.9 81.9 60.3 39.7 19.7 0 mm setback
5.1 4.1 3.2 2.4 1.6 0.8 0 " setback
Firm clay
&
compact silt
0
 16.8 13.2 10.1 8.0 6.3 4.7 3.5 L11 block rows
3.8 3.0 2.3 1.8 1.4 1.1 0.8 meters
12.42 9.75 7.49 5.94 4.62 3.5 2.55 feet
10°
 13.3 10.7 8.5 6.5 4.9 3.9 3.1 L11 block rows
3.0 2.4 1.9 1.5 1.1 0.9 0.7 meters
9.84 7.90 6.24 4.83 3.63 2.91 2.30 feet
22°
 10.2 8.2 5.6 4.0 3.1 2.4 1.7 L11 block rows
2.5 1.8 1.3 0.9 0.7 0.5 0.4 meters
8.28 6.04 4.16 2.97 2.31 1.75 1.28 feet
 
Silty sand
&
sand
0°
 25.9 19.5 14.6 11.1 8.5 6.7 5.2 L11 block rows
5.8 4.4 3.3 2.5 1.9 1.5 1.2 meters
19.15 14.40 10.81 8.17 6.27 4.95 3.83 feet
10°
 23.1 17.0 12.4 9.1 7.1 5.5 4.1 L11 block rows
5.2 3.8 2.8 2.0 1.6 1.2 0.9 meters
17.08 12.45 9.15 6.68 5.28 4.08 3.06 feet
22°
 19.6 13.2 9.6 7.0 5.4 3.9 3.1 L11 block rows
4.4 3.0 2.2 1.6 1.2 0.9 0.7 meters
14.49 9.75 7.07 5.20 3.96 2.91 2.30 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