Appendix D Geotechnical report · MCU18/0013

Project No. 304-2014

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

November, 2004 Page 16
TABLE 6 RETAINING WALL DESIGN PARAMETERS
Material Density Earth Pressure Coefficient Long Term
(kNim’) Flat Top Slope Top Slope 1V:4H__ | Drained
(degrees)
Ka Ko Ka Ko
Compacted Fill * 19 0.41 0.58 0.46 0.76 25
Fill? 17 0.27 0.43 0.31 0.56 35
Loose Sand 17 0.33 0.50 0.37 0.66 30
Medium Dense Sand 18 0.29 0.46 0.33 0.60 33
Dense Sand 20 0.27 0.43 0.31 0.56 35
Very Dense Sand 22 0.21 0.36 0.27 0.47 40
Notes:
1. If fill is compacted against a retaining wall the actual earth pressure could exceed the vertical
pressure (ie. Ka > 1.0).
2. Infers granular free draining material placed behind the retaining wall as a drainage layer.

 

 

6.5.3 Water Regime

Not withstanding the absence of groundwater in all the boreholes and due to possible
long term problems with blocking of gravel filters and drains and short term storm
conditions that could flood the fill behind retaining walls, it is recommended that all
retaining walls be designed for some water pressure distribution. A suggested water
pressure distribution for retaining walls on this site would be one third height water

pressure.
6.5.4 Construction Considerations

A suitable temporary support system must also be determined to ensure the stability of

the retaining wall during excavation for the proposed basement.

It is expected that temporary ground anchors would be required to provide lateral
restraint for the wall. In the long term, this lateral restraint would be provided by the

basement slab floors propping the wall.

It is expected that the temporary anchors would be installed in several rows, at staged
intervals during the excavation of the basement. The design of number of rows, spacing
of anchors and required anchor capacity, would be determined by the retaining wall

designer.

 

#F SOW SURVEYS ENGINEERING