subsidencia 03

8/12/2019 Subsidencia 03

1/19

Diploma Planificacin Minera

Mtodos de prediccin de

Subsidencia en Block Caving


2/19


Implicancias al diseo

Ubicacin infraestructura en superficie

Ubicacin de infraestructura subterrnea

Secuencia de extraccin de sectoresproductivos

Clculo de reservas (angulos de flujo)


3/19


Contenidos

1. Mtodos prediccin subsidencia1. Empricos (Laubscher)

2. Equilibrio limite

Ecuaciones de equilibrio limite

Grficos construidos a partir de analisis de

equilibrio lmite

Modelos numricos


4/19


Laubschers chart to determine cave angle

(angle of break) (Laubscher 2000)


5/19


Ejercicio

Estime el ngulo de quiebre global

utilizando la metodologa de

Laubscher para la secuencia de

dominios representada

Dominio MRMR Profundidad

Altura mineral

quebrado

1 50-60 500 410

2 50-60 400 310

3 50-60 300 210

4 30-40 200 110

5 20-30 100 10


6/19


Evolucin de modelos de equilibrio lmite(Flores y Karzulovic 2004b)


7/19


Scoping and Pre-feasibility

Use design charts:


8/19


Grficos de diseo- angulo de

quiebre

45 50 55 60 65 70 75 80 85 90

Ang le of Break, b(degrees)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

UCL

Dep

th,

HT

(me

ters

)

Rock Mass Geotechnical Qual i ty

Poor to Fair

Fair to Good

Good to Very Good

b

HT

45 50 55 60 65 70 75 80 85 90

Ang le of Break, b(degrees)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

UCL

Dep

th,

HT

(me

ters

)

Rock Mass Geotechnical Qual i ty

Poor to Fair

Fair to Good

Good to Very Good

b

HT

b

HT

Figure 10.1: Design chart for estimating theangle of breakin a transition from open pit to

underground mining by block/panel caving,

for rock masses of different geotechnical

quality and UCL depths in the range from 600

to 1700 m. The value of b

can be obtained if

the UCL depth,H

T

= HP

+ HC, and the rockmass quality are known.


9/19


Grficos de diseo- distancia de influencia

0 50 100 150 200 250 300 350 400 450

Inf luence Zone Width, iz(m )

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

Cra

ter

Dep

th,

HT

=H

P+

HC

(m)

Rock Mass Geotechnic al Qual i ty:

POOR to FAIR H

P= 1200 m

HP= 800 m

HP= 400 m

b

iz

HT

0 50 100 150 200 250 300 350 400 450

Inf luence Zone Width, iz(m )

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

Cra

ter

Dep

th,

HT

=H

P+

HC

(m)

Rock Mass Geotechnical Qual i ty:

POOR to FAIR H

P= 1200 m

HP= 800 m

HP= 400 m

b

iz

HT

b

iz

HT


10/19


0 50 100 150 200 250

Influence Zone Width,IZ

(m)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

CraterDepth,

HT

=

HP

+

HC

(m)

Rock Mass Geotechnical QualityFair to Good

HP

= 1200 m

HP

= 800 m

HP

= 400 m

b

izH

T

0 50 100 150 200 250


(m)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

CraterDepth,

HT

=

HP

+

HC

(m)

Rock Mass Geotechnical QualityFair to Good

HP

= 1200 m

HP

= 800 m

HP

= 400 m

b

izH

T

b

izH

T



11/19


0 20 40 60 80 100 120 140


(m)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

CraterDepth,

HT

=HP

+

HC

(m)

Rock Mass Geotechnical QualityGood to Very Good

HP = 1200 m

HP = 800 m

HP = 400 m

b

izH

T

0 20 40 60 80 100 120 140


(m)

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

CraterDepth,

HT

=HP

+

HC

(m)

Rock Mass Geotechnical QualityGood to Very Good

HP = 1200 m

HP = 800 m

HP = 400 m

b

izH

T

b

izH

T



12/19


Subsidence resulting from BPC operations, El Teniente

Mine, Chile (Flores & Karzulovic 2002)

Braden

Pipe

QuebradaTeniente

Teniente 4

Fortuna

Teniente 4Regimiento

Teniente 5Pilares

Teniente3 Isla

TenienteSub 6

Teniente

4 Sur

N Craterperimeter

Cavedrock


13/19


Plan view of production sectors and subsidence

crater perimeter, El Teniente Mine, Chile (Flores2004a)

Teniente 4

South


14/19


Section A-A showing subsidence data for El

Teniente Mine, Chile (Flores 2004a)

South


15/19


Example of the use of a

design chart to make a

preliminary estimate of angles

of break,

El Teniente Mine, Chile(Flores 2004a)


16/19


Ejercicio

Caso de estudio determinacin ngulos de

quiebre y zona de influencia proyecto

transicin subterrneo:

Profundidad subterrnea: 1600 m

Profundidad pit final: 1200 m

Altura de columna = 500 m

GSI = 60-75 (pared Este)

GSI= 40-55 (pared Oeste)


17/19


Efecto y ajustes de la superficie debido a

confinamiento (after Hoek 1970)

r= horizontal radius of curvature of slope, h= slope height

Concavo

Convexo


18/19


Suggested adjustments for curvature of a

concave subsidence crater wall (after Flores 2004a)

If r/hs< 1, the slope will be much more stable than a straightslope. Use the chart or calculated value as a lower bound tothe angle of break; add 10oto estimate an upper bound

If 1 < r/hs< 2, use the chart or calculated value as a lower

bound to the angle of break; add 5o

to estimate an upperbound

If 2 < r/hs< 5, the slope will be slightly more stable than a

straight slope. Use the chart or calculated value as aconservative estimate of the angle of break

If r/hs> 5, use the unadjusted chart or calculated value


19/19


Suggested adjustments for curvature of a

convex subsidence crater wall (after Flores 2004a)

If r/hs< 1, the slope will be much less stable than a straight slope.

Use the chart or calculated value as an upper bound to the angleof break; subtract 10oto estimate a lower bound

If 1 < r/hs< 2, use the chart or calculated value as an upper

bound to the angle of break; subtract 5oto estimate a lowerbound

If 2 < r/hs< 5, the slope will be slightly less stable than a straight

slope. Use the chart or calculated value as an upper bound to

the angle of break; subtract 2

o

to estimate a lower bound

If r/hs> 5, use the unadjusted chart or calculated value

subsidencia 03

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