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

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

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<strong>The</strong> <strong>Delft</strong> <strong>Sand</strong>, <strong>Clay</strong> & <strong>Rock</strong> <strong>Cutting</strong> <strong>Model</strong>.<br />

<strong>The</strong> unknowns in this equation are K3 and K4, since K2 has already been solved. Two other unknowns are the<br />

external friction angle δ, since also the external friction does not have to be fully mobilized, and the wedge angle<br />

θ. <strong>The</strong>se 2 additional unknowns require 2 additional conditions in order to solve the problem. One additional<br />

condition is the equilibrium of moments of the wedge, a second condition the principle of minimum required<br />

cutting energy. Depending on whether the soil pushes upwards or downwards against the blade, the mobilization<br />

factor is between -1 and +1.<br />

<strong>The</strong> force K3 on the bottom of the wedge is now:<br />

K<br />

3<br />

<br />

sin <br />

K2 sin G2 sin <br />

<br />

<strong>The</strong> force K4 on the blade is now:<br />

K<br />

4<br />

<br />

sin <br />

K2sin G2 sin <br />

<br />

(11-16)<br />

(11-17)<br />

This results in a horizontal force on the blade of:<br />

h 4<br />

<br />

<br />

F K sin<br />

(11-18)<br />

And in a vertical force on the blade of:<br />

v 4<br />

<br />

<br />

F K cos<br />

(11-19)<br />

Figure 11-4: <strong>The</strong> forces on the layer cut when a wedge is present.<br />

Page 336 of 454 TOC Copyright © Dr.ir. S.A. Miedema

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