Hydro-Mechanical Properties of an Unsaturated Frictional Material

216 APPENDIX A. DETAILS ZOU’S MODEL (2003, 2004)
and ζ > 1 is a meniscus parameter which describes the physical properties of soil particle
surfaces.
According to the so-called capillary law (Fredlund & Rahardjo 1993b), the dimensionless
suction σu(y) in pore water during wetting and draining the frustum-shaped pores, depending
on r and β and so that on y, can be expressed as:
σu(y) = (ua − uw) · rs
Ts
= 2 cos β
=
r/rs
�
B 2 cos · A−y/rs
�
b
a−y/rs
+ c
�0.5 + C
� 0.5
(A.14)
Now using equations Eq. A.10 and Eq. A.3 the relationship between degree of saturation
Sr(α) and suction σu(α) during wetting and draining the contact regions for 0 < α ≤ αmax
can be calculated, and using equations Eq. A.10 and Eq. A.14 the relationship between Sr(y)
and σu(y) during wetting and draining the frustum-shaped pores for 0 < y ≤ rs can be also
estimated.