1 Introduction
2 Underground Quarrying with Water Jet
2.1 Combination of Diamond wire and Water Jet
2.2 Slotting with Oscillating Water Jet
2.3 State of Stress in Underground Quarrying
3 The Experimental Research
3.1 Rock Samples and Experimental Set-up
Property | Value |
---|---|
Bulk specific gravity [kg/m3] | 2.588 |
Absorption coefficient [%] | 4.85 |
Porosity [%] | 0.63 |
Compressive strength [MPa] | 192 |
Flexural strength (MPa) | 156 |
Impact test (Height of fall) [cm] | 68 |
P-wave velocity [m/s] | 5626 |
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a Hammelmann High-Pressure plunger pump (power at the engine flywheel: about 300 kW; maximum flowrate: 54 l/min at 250 MPa;
-
an oscillating lance (top frequency: f = 20 Hz; maximum traverse velocity vt: 15 m/min);
-
a block carrier platform;
-
a programmable lance control unit;
-
a specially designed uniaxial compression cell provided with a hydraulic jack capable of imparting a load up to 100 t.
Parameter | Value |
---|---|
Water jet generation pressure [MPa] | 100, 160, 200 |
Nozzle diameter Φ [mm] | 0.96 |
Stand – off distance SOD [mm] | 20 |
Jet impact angle β | 50° |
Oscillation frequency f [Hz] | 20 Hz |
Sweeping angle α | 22° on each side |
Advancement per cycle [y-direction] a [mm] | 2 |
Transverse velocity [z-direction] vt [m/min] | variable |
3.2 Test on Unloaded Samples
Test | Sample N° | Load (kN) | Jet pressure p (MPa) | Advancement a (mm) |
---|---|---|---|---|
Z1 | Z1a, Z1b, Z1c | 0 | 100 | 2 |
Z2 | Z2a, Z2b, Z2c | 0 | 160 | 2 |
Z3 | Z3a, Z3b, Z3c | 0 | 200 | 2 |
3.3 Test on Compressed Samples
Water jet generation pressure p (MPa) | Cutting rate steps CR* (m2/h) |
---|---|
100 | 0.45–0.36–0.30 |
160 | 1.30–1.10–0.90–0.85 |
200 | 1.79–1.78–1.75–1.65 |
Test | Sample N° | Load (kN) | Jet pressure p (MPa) | Traverse velocity vt (m/min) | Advancement a (mm) | Cutting rate CR* (m2/h) |
---|---|---|---|---|---|---|
C1 | C1a, C1b, C1c | 250 | 100 | 3.75–3.0–2.5 | 2 | 0.45–0.36–0.30 |
C2 | C2a, C2b, C2c | 500 | 100 | 3.75–3.0–2.5 | 2 | 0.45–0.36–0.30 |
C1’ | C1’a, C1’b, C1’c | 250 | 160 | 10.83–9.17 | 2 | 1.30–1.10 |
C2’ | C2’a, C2’b, C2’c | 500 | 160 | 7.50–7.08 | 2 | 0.90–0.85 |
C1’’ | C1’’a, C1’’b, C1’’c | 250 | 200 | 14.9–14.8 | 2 | 1.79–1.78 |
C2’’ | C2’’a, C2’’b, C2’’c | 500 | 200 | 14.6–13.7 | 2 | 1.75–1.65 |
3.4 Test on Tense Samples
Sample N° | Flexural load (kN) | Jet pressure p (MPa) | Traverse velocity vt (m/min) | Advancement a (mm) | Cutting rate CR* (m2/h) | |
---|---|---|---|---|---|---|
T1 | T1a T1b T1c | 50 | 100 | 5.75–6.08 | 2 | 0.69–0.73 |
T2 | T2a T2b T2c | 100 | 100 | 7.00–8.33 | 2 | 0.84–1.00 |
3.5 Test Results
Test | Samples | Jet pressure (MPa) | Traverse velocity vt (m/min) | Advancement a (mm) | Cutting rate CR* (m2/h) |
---|---|---|---|---|---|
Z1 | Z1a Z1b Z1c | 100 | 5.25 = (5.5 + 4.9 + 5.2)/3 | 2 | 0.63 |
Z2 | Z2a Z2b Z2c | 160 | 11.7 = (11.0 + 12.5 + 11.5)/3 | 2 | 1.40 |
Z3a Z3b Z3c | 200 | 15.1 = (14.8 + 15.0 + 15.3)/3 | 2 | 1.84 |
Test | Jet pressure p (MPa) | Lateral load (kN) | Cutting rate CR* (m2/h) | Limit slot depth (mm) |
---|---|---|---|---|
C1 (a, b, c) | 100 | 250 | 0.45 | 25 = (24.5 + 26 + 25)/3 |
0.36 | 35 = (36 + 33.5 + 35)/3 | |||
0.30 | 60 = (58 + 61 + 60.5)/3 | |||
C2 (a, b, c) | 100 | 500 | 0.45 | 8 = (7.5 + 9 + 8)/3 |
0.36 | 15 = (13.5 + 15 + 16)/3 | |||
0.30 | 25 = (27 + 25 + 24)/3 | |||
C1 (a’, b’, c’) | 160 | 250 | 1.30 | 23 = (22.5 + 24 + 22)/3 |
250 | 1.10 | 61 = (60 + 63 + 60.5)/3 | ||
C2 (a’, b’, c’) | 160 | 500 | 0.90 | 44 = (45 + 44 + 42)/3 |
500 | 0.85 | 64 = (63.5 + 65 + 64)/3 | ||
C1(a’’, b’’, c’’) | 200 | 250 | 1.79 | 40 = (41 + 40 + 39)/3 |
250 | 1.78 | 65 = (63.5 + 66 + 64)/3 | ||
C2 (a’’, b’’, c’’) | 200 | 500 | 1.75 | 65 = (66 + 63 + 65)/3 |
500 | 1.65 | 82 = (81 + 83 + 82.5)/3 |
Test | Flexural load (kN) | Cutting rate CR* (m2/h) | Limit slot depth (mm) |
---|---|---|---|
T1 (a, b, c) | 50 | 0.69 | 5 (4.5 + 6 + 5)/3 |
0.73 | 30 (30.5 + 29.6 + 29.8)/3 | ||
T2 (a, b, c) | 100 | 0.84 | 30 (30.1 + 29.2 + 30.7)/3 |
1.00 | 50 (51 + 48.5 + 49)/3 |
3.6 State of Stress Simulation
4 Discussion
4.1 Research Objective and Assumptions
4.2 Correlations and Comprehensive Results Link
Test sample | Cutting rate (CR*) (m2/h) | Measured limit depth (mm) | Model | Lateral load (kN) | Simulated limit condition (depth of groove (mm)) | SubModel | Sσxx (-) Eσxx ( +) (MPa) |
---|---|---|---|---|---|---|---|
C1,a,b,c | 0.45 | 25 | CM1 | 250 | 25 | CM1α | − 11.6 |
0.36 | 35 | 35 | CM1β | − 15.0 | |||
0.30 | 60 | 60 | CM1χ | − 26.8 | |||
C2a,b,c | 0.45 | 8 | CM2 | 500 | 8 | CM2α | − 12.6 |
0.36 | 15 | 15 | CM2 β | − 15.4 | |||
0.45 | 25 | 25 | CM2χ | − 22.4 | |||
C1 a’, b’, c’ | 1.30 | 23 | CM1’ | 250 | 23 | CM1α’ | − 11.0 |
1.1 | 61 | 61 | CM1 β’ | − 28.0 | |||
C2 a’, b’, c’ | 0.90 | 44 | CM2’ | 500 | 44 | CM2α’ | − 44.5 |
0.83 | 64 | 64 | CM2β’ | − 63.0 | |||
C1a’’, b’’, c’’ | 1.79 | 40 | CM1’ | 250 | 40 | CM1α’’ | − 18.0 |
1.78 | 65 | 65 | CM1β’’ | − 32.0 | |||
C2a’’, b’’, c’’ | 1.75 | 65 | CM2’ | 500 | 65 | CM2α’’ | − 65.0 |
1.65 | 82 | 82 | CM2β’’ | − 80.0 | |||
T1a,b,c | 0.69 | 5 | TM1 | 50 | 5 | TM1α | + 2.5 |
0.73 | 30 | 30 | TM1β | + 3.2 | |||
T2a,b,c | 0.84 | 30 | TM2 | 100 | 30 | TM2α | + 6.4 |
1.00 | 50 | 50 | TM2β | + 8.0 |
Generation pressure (MPa) | ∆CR/ ∆σxx (m2/h)/MPa |
---|---|
200 | − 1.10E3 |
160 | − 8.4E3 |
100 | − 1.4E2 |