Deformation parameters - Geotechnical Investigation and Design Tables - page 132

Table 11.17 Poisson's ratio for soils (Industrial floors and pavements guidelines, 1999).

Material Short term Long term

Sands, gravels and other cohesionless soils 0.30 0.30

LowPI(

<

12%) 0.35 0.25

Medium PI (12% PI 22%) 0.40 0.30

< <

High PI (22% PI 32%) 0.45 0.35

< <

Extremely high PI (PI

>

32%) 0.45 0.40

11.18 Typical rock deformation parameters
•

The higher density rocks have a larger intact modulus.

•

This needs to be factored for the rock defects to obtain the in-situ modulus.

Table 11.18 Rock deformation based on rock description (adapted from Bell, 1992).

Rock density (kg/m 3 ) Porosity (%) Deformability (10 3 MPa)

<

1800

>

30

<

5

1800-2200 30-15 5-15

2200-2550 15-5 15-30

2550-2750 5-1 30-60

2750 1 60

> < >

11.19 Rock deformation parameters
•

This table is for intact rock properties, and compares the Young's modulus (E) to
the unconfined strength (q u ).

Table 11.19 Rock modulus values (Deere and Miller, 1966).

E/q u Material Comments

1000 Steel, concrete Man made materials

500 Basalts & other flow rocks (Igneous rocks) High modulus ratio - UCS 100 MPa

>

Granite (Igneous)
Schist: low foliation (Metamorphic) Basalt in Brisbane was 300

Marble (Metamorphic) Phyllite (Foliated metamorphic) in

Brisbane was 500

200 Gneiss, Quartzite (Hard metamorphic rocks) High modulus ratio - UCS 60-100 MPa =

Limestone (Sedimentary)
Dolomite (Calcareous sedimentary: coral)

100 Shales, sandstones (Sedimentary rocks) Low modulus ratio - UCS

<

60 MPa

Schist: steep foliation Horizontal bedding: Lower the E values

tuff (Pyroclastic Igneous) in Brisbane was 150

•

Intact rock properties would vary from in-situ conditions depending on the defects.