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

8.10.3. Step 3: Applying Tensile Strengths of -5 MPa, -10 MPa and -25 MPa.<br />

From Figure 8-49 and Figure 8-50 the horizontal and vertical peak forces can be determined. <strong>The</strong>y are given in the<br />

following table. Between brackets estimated average values, based on a 60% ratio between average and peak<br />

values.<br />

Table 8-3: Resulting forces and specific energy.<br />

Tensile<br />

Strength<br />

Fh (N) Fv (MN) Esp (MPa) Esp/UCS<br />

(%)<br />

-5 MPa 0.207 (0.124) 0.062 (0.037) 20.7 (12.4) 20.7 (12.4)<br />

-10 MPa 0.446 (0.268) 0.134 (0.080) 44.6 (26.8) 44.6 (26.8)<br />

-25 MPa 0.669 (0.401) 0.200 (0.120) 66.9 (40.1) 66.9 (40.1)<br />

<strong>The</strong> UCS/BTS ratio of 10 matches the findings of Roxborough (1987) giving a specific energy of about 25% of<br />

the UCS value.<br />

Esp<br />

0.25 U.C.S. 0.11<br />

(8-142)<br />

8.11. Nomenclature.<br />

a, a Adhesive shear strength kPa<br />

A Adhesive force on the blade kN<br />

BTS Brazilian Tensile Strength kPa<br />

c, c Cohesive shear strength kPa<br />

cm Mobilized cohesive shear strength kPa<br />

C Cohesive force on shear plane kN<br />

Esp Specific energy kPa<br />

F Force kN<br />

Fc <strong>Cutting</strong> force on chisel Evans model kN<br />

Fn Normal force on chisel Evans model kN<br />

Fch Horizontal force component Evans model kN<br />

Fcv Vertical force component Evans model kN<br />

Fh Horizontal cutting force kN<br />

Fv Vertical cutting force kN<br />

g Gravitational constant (9.81) m/s²<br />

G Gravitational force kN<br />

hi Initial thickness of layer cut m<br />

hb Height of the blade m<br />

K1 Grain force on the shear plane kN<br />

K2 Grain force on the blade kN<br />

I Inertial force on the shear plane kN<br />

n Power in Nishimatsu model -<br />

N1 Normal grain force on shear plane kN<br />

N2 Normal grain force on blade kN<br />

p Stress in shear plane Nishimatsu model kPa<br />

p0 Stress at tip of chisel Nishimatsu model kPa<br />

Pc <strong>Cutting</strong> power kW<br />

Q Production m 3<br />

r Radius in Evans model m<br />

r Adhesion/cohesion ratio -<br />

r1 Pore pressure on shear plane/cohesion ratio -<br />

r2 Pore pressure on blade/cohesion ratio -<br />

R Radius of Mohr circle kPa<br />

R Force on chisel Evans model kN<br />

Copyright © Dr.ir. S.A. Miedema TOC Page 295 of 454

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