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

The Delft Sand, Clay & Rock Cutting Model.
cut also includes the mass of the pore water. The wet density of saturated sand or gravel is usually close to ρs=2
ton/m 3 , while the submerged weight is close to (ρs-ρw)·g=10 kN/m 3 (a porosity of 40% and a quarts density of
ρq=2.65 ton/m 3 are assumed). This will double the contribution of the inertial forces as determined by the
following dimensionless parameter:
2 s
w
2
c
2
vc
v
i
gh gh
i s i
(5-31)
Using this dimensionless inertial effect parameter λi, the cutting forces can be determined by:
2
h s w i i HD i i HI
F gh w 1 f f (5-32)
2
F gh w 1 f f
v s w i i VD i i VI
(5-33)
The specific energy is now:
sp s w i i HD i i HI
E g h 1 f f (5-34)
Under water at high cutting velocities there may also be a drag force which has not been taken into account here.
The horizontal cutting force coefficients λHD and λHI can be found in Figure 5-11 and Figure 5-16. The vertical
cutting force coefficients λVD and λVI can be found in Figure 5-12 and Figure 5-17.
The cutting forces calculated are for a plane strain 2D cutting process, so 3D side effects are not included.
Figure 5-18: A dredging wheel used in the German braunkohl mines (www.wikiwand.com).
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