Deformation parameters - Geotechnical Investigation and Design Tables - page 128

- These modulus values should not be used in a different application, ie non

foundations.

- For example, the modulus values of similar soils in a trench as backfill

surrounding a pipe would be significantly less than the above values.

11.8 Typical values for coefficient of volume compressibility
•

The coefficient of volume compressibility (m v ) is used to compute settlements for
clay soils.

•

The m v value is obtained from the consolidation (odeometer) test. This test is one
dimensional with rigid boundaries, ie the Poisson Ratio υ = 0 and E = 1/m v .

•

The elastic modulus is referred to as the constrained modulus and is based on the
assumption that negligible lateral strain occurs (in odeometer), so that Poisson's
ratio is effectively zero.

•

One-dimensional settlements = ρ

od .

Table 11.8 Typical values for coefficient of volume compressibility (after Carter, 1983).

Type of clay Descriptive term Coefficient of volume Constrained

compressibility, modulus,

Strength Compressibility m v (10 − 3 kPa − 1 ) 1/m v , (MPa)

Heavily overconsolidated Hard Very low 0.05 20 < >

boulder clays, weathered
mudstone.
Boulder clays, tropical red Very stiff Low 0.05 to 0.1 10-20

clays, moderately
overconsolidated.
Glacial outwash clays, lake Firm Medium 0.1-0.3 3.3-10

deposits, weathered marl,
lightly to normally
consolidated clays.
Normally consolidated

Soft High 0.3-1.0 (non sensitive) 0.7-3.3

alluvial clays such as 0.5-2.0 (organic, sensitive)

estuarine and delta
deposits, and sensitive
clays.
Highly organic alluvial Very soft Very high 1.5 0.7 > <

clays and peat.

11.9 Coefficient of volume compressibility derived from SPT
•

The m v value is inversely proportional to the strength value. The correlation
with the SPT N-value is provided in the table for clays with varying plasticity
index.

•

The table was based on data for stiff clays.