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Design table - Terraforce L15 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 93 73 54 35 17 0 mm setback
4.5 3.7 2.9 2.1 1.4 0.7 0 " setback
Firm clay
&
compact silt
0
 16.3 13.0 10.1 7.8 5.9 4.5 3.6 L15 block rows
3.3 2.6 2.0 1.6 1.2 0.9 0.7 meters
10.7 8.5 6.7 5.1 3.9 2.9 2.4 feet
10°
 13.0 10.5 8.3 6.4 4.9 3.8 3.1 L15 block rows
2.6 2.1 1.7 1.3 1.0 0.8 0.6 meters
8.5 6.9 5.4 4.2 3.2 2.5 2.0 feet
22°
 10.8 8.0 5.7 4.0 2.8 2.1 1.9 L15 block rows
2.2 1.6 1.1 0.8 0.6 0.4 0.4 meters
7.1 5.2 3.7 2.6 1.8 1.4 1.2 feet
 
Silty sand
&
sand
0°
 25.1 19.4 14.6 10.9 8.1 6.2 5.3 L15 block rows
5.0 3.9 2.9 2.2 1.6 1.2 1.1 meters
16.5 12.7 9.6 7.2 5.3 4.1 3.5 feet
10°
 22.3 16.9 12.5 9.1 6.6 5.0 4.4 L15 block rows
4.5 3.4 2.5 1.8 1.3 1.0 0.9 meters
14.6 11.1 8.2 6.0 4.3 3.3 2.9 feet
22°
 17.2 13.1 9.6 6.9 4.9 3.7 3.2 L15 block rows
3.4 2.6 1.9 1.4 1.0 0.7 0.6 meters
11.3 8.6 6.3 4.5 3.2 2.4 2.1 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