geotechnical report

The sample hand collected and classified on site from BH 1 at a depth of 1100 mm
below the existing surface level returned a linear shrinkage result of 10.6%.

The expected surface movement (Ys) of the natural soil profile, due to seasonal
moisture changes in the soil encountered, is as follows

 

Ys Value = 25mm

 

 

 

 

 

 

 

 

 

 

 

 

 

Predicted Surface Movement Class
Ys=< 20mm S
Ys=>20-—< 40mm M
Ys => 40-< 60 mm Hl
Ys =>60-—< 75mm H2
Ys=>75 mm E
Problem sites P

 

Note: The proximity of trees and their effect on foundations should be considered when
determining specific engineering assessments, and for foundation/footing design.
Appendix B of AS 2870-2011 indicates that to reduce, but not eliminate, the possibility of
damage to the footings, trees should be restricted to the following distance from the
building (where rows or groups of trees are present the distance nominated below must
be increased, and similarly the Ys Value listed above may need to be increased) : 75% of
the mature tree height, for class “M” sites, 100% of the mature tree height, for class
“H 1” sites, and 150% of the mature tree height, for class “E” sites.

Note: Problem (P) sites are normally classified because of limited bearing strengths
at normal footing depths. In this instance be aware of the depth of the fill on the near
level cut fill pad and the effects of differential surface movements.

Note: This classification above has been derived from test work performed on the soil
profile encountered on the day of our fieldwork. Any further filling of the site or
excavation into the soil profile, may result in a different classification.

Temporary Excavations.

Where temporary excavations are performed for footing or services up to 600mm
deep, natural soils may have minor or no stability problems, however deeper
excavations have a possibility of collapse more readily and shoring of vertical
excavation may be required. Where an existing excavation has been filled with
uncontrolled fill, all locations above a line 30 degrees for sands and 45 degrees for
clays above the horizontal may be unstable and may not support any structure — see
attached critical depth line diagram.

 

Unearthed Geotechnical P/L. 4 Site Investigation Report 022-003