Improvement of fine-grained and cohesive soils 117
Another important parameter of the infinite grid pattern is the area replacement ratio a c calculated as ratio of column area A c and total unit cell area A:
a
A
A C
d
d
c
c
e
=
=
⋅






1
2
2
(4.2)
As the unit cell is symmetric by geometry, a uniform load evenly distributed over the infinitely extended area and applied by a rigid raft will not
20
200
2
500
100
50
10
5
1
Undrained shear strength c
u (kPa)
Consistency index (−)
A c c o r d i n g t o W
r o t h
a n d
W
o o d
Hard
Very
stiff
Firm Soft
Very soft
Stiff
Very hard Stiff Firm Soft Very soft
Hard Stiff Firm Soft
Very soft
According to ASTM
According to BS
According to PIANC
Solid
Voids
Solid material
Plastic
Semisolid
Liquid
Volume
Shrinkage limit
Plasticity limit
Liquid limit
W(%)
Consistency index
Phase
0.50
0.75
Plasticity index
Water
Air
0
1
Stiff
Very stiff
According to DIN EN ISO14688 T.2
Firm
Very
soft
0.25
Soft
Range of
vibro
replacement
Figure 4.7 Water content, consistency, and shear strength of fine-grained cohesive soils.
(Based on CUR, Building on Soft Soils. Centre for Civil Engineering Research
and Codes. A.A. Balkema, Rotterdam, the Netherlands, 1996.)