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

Saturated Sand Cutting.
S1=L1*(1-I/N)
‘Determine the resistance of the top of the blade to point I
R1=S1/Kmax
‘Determine the effective resistance in point I
Rt=1/(1/R1+1/R2)
‘Determine the flow at the tip of the blade
IF I>TipEffect THEN
Q=Q-Q2
ELSE
Q=Q+Q2
END IF
‘Determine the 2 flows
Q1=Q*Rt/R1
Q2=Q*Rt/R2
‘Determine the pore vacuum pressure in point I
DP=Rhow*G*Q*Rt
‘Integrate the pore vacuum pressure
P = P + DP
‘Store the pore vacuum pressure in point I
P2(I)=DP
Next I
‘Determine the average pore vacuum pressure with correction for integration
P2m = (P - Ptip / 2) / N
Figure 6-21: A small program to determine the pore pressures.
0.500
Pore Pressures on the Blade (α=30º) & the Shear Plane (β=30º) - kmax/ki=4 & hb/hi=3
Dimensionless Pore Pressure p 1 & p 2 (-)
0.475
0.450
0.425
0.400
0.375
0.350
0.325
0.300
0.275
0.250
0.225
0.200
0.175
0.150
0.125
0.100
0.075
0.050
0.025
p1
p2
0.000
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Percentage of Blade & Shear Plane (%)
B-C
A
© S.A.M.
Figure 6-22: The dimensionless pressures on the blade and the shear plane,
α=30°, β=30°, ki/kmax=0.25, hi/hb=1/3.
Figure 6-21 shows a program listing to determine the pore pressures with the analytical/numerical method. Figure
6-22, Figure 6-23 and Figure 6-24 show the resulting pore vacuum pressure curves on the shear plane and on the
blade for 30, 45 and 60 degree blades with a hi/hb ratio of 1/3 and a ki/kmax ratio of 1/4. The curves match both the
FEM calculations and the experiments very well.
Copyright © Dr.ir. S.A. Miedema TOC Page 143 of 454