The Delft Sand, Clay & Rock Cutting Model, 2019a

The General Cutting Process.
2 2 2
sin sin sin
Fh
r cos sin 2 sin sin sin
2 2 2
sin sin sin
sin sin 2 sin sin cos
(3-31)
2 2 2
sin sin
sin
sin sin 2 r sin sin cos
In the special case where there is no adhesion, r 0, the shear angle is:
0
2 2
sin sin
Fh
sin 2 sin cos
0
(3-32)
So:
sin 2
0 for 2 giving = (3-33)
2 2
The cohesion c can be determined from the UCS value and the angle of internal friction φ according to (as is shown
in Figure 3-12):
UCS 1
sin
c
2
cos
(3-34)
According to the Mohr-Coulomb failure criterion, the following is valid for the shear stress on the shear plane, as
is shown in Figure 3-13.
S1
N1
c tan (3-35)
Figure 3-12: The Mohr circle for UCS and cohesion.
Copyright © Dr.ir. S.A. Miedema TOC Page 83 of 454