Page 180 - Buried Pipe Design

154 Chapter Three

m
B P a
K b

m
B K P s 3
b a
P a

s 3
P a
Figure 3.41 Variation of bulk modulus with confining pressure.
(After Duncan et al. 6 )

s m
B
1 Figure 3.42 Illustration of mean
stress versus volumetric strain
during a hydrostatic compres-
sion test.
ΔV
= e u
e vol V 0
slope of this curve is equivalent to the bulk modulus. Selig suggested
that the shape of this curve is best fit by:
B ε
σ = i vol (3.38)
m ε
1 − vol
ε
u
where B initial tangent bulk modulus
i
vol volumetric strain
ultimate volumetric strain
u