Page [S] [L12] [L13] [L18] [L22] [L11] [L15] [4x4] [Lite]
Design table - Terraforce L18 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
 17.1 13.4 10.3 8.2 6.4 4.8 3.5 L18 block rows
3.4 2.7 2.1 1.6 1.3 1.0 0.7 meters
11.21 8.80 6.76 5.36 4.17 3.15 2.30 feet
10°
 13.5 10.9 8.6 6.6 5.0 4.0 3.2 L18 block rows
2.7 2.2 1.7 1.3 1.0 0.8 0.6 meters
8.87 7.13 5.63 4.35 3.27 2.63 2.07 feet
22°
 11.4 8.3 5.7 4.1 3.2 2.4 1.8 L18 block rows
2.3 1.7 1.1 0.8 0.6 0.5 0.4 meters
7.47 5.45 3.75 2.68 2.08 1.58 1.15 feet
 
Silty sand
&
sand
0°
 26.3 19.8 14.9 11.2 8.6 6.8 5.3 L18 block rows
5.3 4.0 3.0 2.2 1.7 1.4 1.1 meters
17.28 12.99 9.76 7.37 5.66 4.47 3.45 feet
10°
 23.5 17.2 12.6 9.2 7.3 5.6 4.2 L18 block rows
4.7 3.4 2.5 1.8 1.5 1.1 0.8 meters
15.41 11.32 8.26 6.03 4.76 3.68 2.76 feet
22°
 19.9 13.4 9.7 7.1 5.4 4.0 3.2 L18 block rows
4.0 2.7 1.9 1.4 1.1 0.8 0.6 meters
13.08 8.80 6.38 4.69 3.57 2.63 2.07 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