This article shows validation and design examples for sleeper retaining walls in cohesive soils to Australian Standards.

Example 1 - 1.4m retained height & 2m spacing of posts

Reference: Tuff Ozzy Concrete Sleepers Technical Design Guide Rev A - Mar 2020 **Section 4.0 (**link: TUFF-OZY-TECHNICAL-DESIGN-GUIDE2.pdf) Tuff Ozzy Design guide covers a range of typical sleeper retaining walls. A deemed-to-comply size and spacing of posts is given, without specific details on moment or shear demand/capacity. Deflection Limits are assumed not to be checked in Tuff Ozzy, which ClearCalcs provides additionally. The advice is based on typical retaining wall applications in QLD.

1. Inputs

1.1 Pile/Steel Post Inputs

Pile ParametersValue [Reference]
Concrete Strength25 MPa concrete [Sec 2.3]
Minimum Cover to Steel Member in Pile100 mm [Sec 2.3]
Diameter of Pile400 mm [Sec 2.2]
Steel Post100 UC 15 [Sec 4.0] - Assumed Gr.350 conservative

1.2 Wind Inputs

Wind ParametersValue [Reference]
Wind RegionB [Sec 2.4]
Terrain Category2 [Sec 2.4]
Wind Classification [AS4055] **
N3 [Sec 2.4]
** Wind Classification is not given in Tuff Ozzy Design Guide, however is derived per below for No Shielding = NS, and flat terrain (Topographic Class = T1)

1.3 Soil Inputs

Tuff Ozzy Design Manual assumes same soil parameters for retained and foundation soil.
Soil ParametersValue [Reference]
Density Ξ³1 (Retained Soil)1900kg/m3 ~= 18.6 kN/m3 [Sec 2.5]
Characteristic Angle of Internal Friction ϕ’1 (Retained Soil)25 deg [Sec 2.5]
Cohesion c_275 kPa [Sec 2.5]
Soil Condition (Foundation & Retained)Controlled Fill - Class 1 [Sec 2.5]

1.4 Loading

Loading ParametersValue [Reference]
Structure Classification’A’ per AS4678‐2002 [Sec 2.6]
Surcharge Load2.5 kPa [Sec 2.6]
Load FactorsNot stated (conservative to compare with 1.0x factor) [no ref.]
Ground Water LevelNone [Sec 2.7]

1.5 Fence

Fence DimensionsValue [Reference]
Fence Height hf1.8m [Sec 4.0]
Length of Retaining Wall FenceGeneral Zone = >7.2m [Sec 4.0] - assumed 20m
Solidity
1.0 [no ref. => 1 is conservative]

1.6 Limitations

  • SEC 2.2 Sleeper retaining walls within this brochure are not permitted to be installed within 1km of the coastline, or a large body of salt water.
  • SEC 2.4 ‐ General Zone: A maximum 1800 high fence that is further than 3.6m away from a free end may be installed on top of the wall. Fence posts located within this β€˜general zone’ are subjected to only half the wind pressure of those within the β€˜end zone’
  • SEC 2.4 - Please note that this design guide does not cover fences within cyclonic areas.
  • SEC 2.8.3 - The design graphs in section 5.0 of this brochure have made no allowance for a battered backfill (refer Figure 4 in section 5.0).

2. Outputs

Tuff Ozzy Design Manual provides a deemed-to-comply chart output. ClearCalcs results are therefore plotted on the same chart. The results are slightly more conservative in ClearCalcs (within 10%). If more typical surcharge load / soil load factors are assumed, ClearCalcs would be additionally conservative compared to Tuff Ozzy Design Manual.
ValueExampleClearCalcs
Moment Capacity of Steel PostApprox 95%101 %
Minimum Depth of Embedment of Piles Below Bottom of Wall hp,min1430 mm1520 mm