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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>Rock</strong> cutting under atmospheric conditions (normal dredging) is dominated by the internal shear strength and by<br />

the internal and external friction angles. <strong>The</strong> main cutting mechanism is the Chip Type, brittle cutting. <strong>Cutting</strong> a<br />

very thin layer or using large blade angles may result in the Crushed Type. This is covered in Chapter 8: <strong>Rock</strong><br />

<strong>Cutting</strong>: Atmospheric Conditions.<br />

Figure 4-6: <strong>The</strong> Crushed Type in atmospheric rock cutting.<br />

Figure 4-7: <strong>The</strong> Chip Type in atmospheric rock cutting.<br />

<strong>The</strong> forces K1 and K2 on the blade, chisel or pick point are now:<br />

K<br />

K<br />

1<br />

2<br />

W2<br />

sin( ) W1<br />

sin( ) G sin( )<br />

<br />

sin( )<br />

Icos( ) Ccos( )<br />

Acos( )<br />

<br />

sin( )<br />

W2<br />

sin( ) W1<br />

sin( ) G sin( )<br />

<br />

sin( )<br />

I cos( ) Ccos( )<br />

A cos( )<br />

<br />

sin( )<br />

(4-19)<br />

(4-20)<br />

<strong>The</strong> normal forces N1 on the shear plane and N2 on the blade are:<br />

<br />

<br />

N 1 K1<br />

cos and N 2 K2<br />

cos<br />

(4-21)<br />

Page 100 of 454 TOC Copyright © Dr.ir. S.A. Miedema

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