06 nuevo método para obtener un criterio de diseño optimo de precorte ... ppt asiex 2012

8/10/2019 06 Nuevo Mtodo Para Obtener Un Criterio de Diseo Optimo de Precorte ... PPT ASIEX 2012

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Asiex 2012

NEW METHOD TO OBTAIN OPTIMUM PRE-

SPLITTING DESIGN CRITERIA CONSIDERING

THE ROCK MASS PROPERTIES

Alvaro Gonzalez, Car los Muoz1, lvaro Andrades

South Region Technical Services, Orica Mining [email protected]


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Wall Control is directly related to:

Sustainability

Mining Costs

Mining plans and opportunity costProductivity

Mine profitability

Why Wall Control?


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Typical Wall Control values

>15 MUSD/Year


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The influence of rock blasting in the slope stability

Pre-Split &

Buffer rows

Vibrations

& resonance in the far fiel

?!


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Typical blast damageover benches


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The Pre-Splitting practice-An introduction

Is the most used technique in the named controlled blasting. Basically it consist in to obtain a pre-split plane that permit to

control the rock blasting damage.

To control and reduce seismic vibrations from the rockblasting.

To reduce back break and reopening of preexisting geologicalstructures.

Safety of people and equipments working around benches.

Maintain integrity of benches, final highwalls and overall pit

slope angle. To reduce bench remediation costs.


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The Pre-Splitting practices-An introduction

Pre Split design is directly related to buffer row design


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Basically the pre-split practice consist of detonates twosimultaneous de-coupled explosives charge spaced to a S distance

The detonation of the explosive charges produces a stress that it is transmitted to the rock

massif in form of shock wave and gas pressure. The last one is considered as the responsible

for the creation of the pre-split planes.


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The objectives is to obtain a pre-split plane that permit to

reduce damage related to rock blasting


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The Pre-Splitting practices-An introduction

The most used formula for to obtain the S distance between two de-coupled charges at

which the pre-split plane can be obtained is based on Sanden (1974)

Current methods consider only the static

tensile strength and a constant decay of

borehole pressure with the square of

distance.


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The Pre-Splitting practices-An introductionCurrent methods can not be scaled to rock massif


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Dynamic method for pre-splitting design

The dynamic method to pre-split design follows the work developed for Liu and Katsabanis

(1993) and Onederra et al (2004)

The pressure decay proposed by Liu and Katsabanis;

Ror


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Relation between Vp and Pre-Split Spacing


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Anlisis para un macizo fracturado con Vp < 3,000 m/s, RQD


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2.3 ton/mt

2.6 ton/mt

2.8 ton/mt

4.7 ton/mt

Mtodo canadiense

Relation between density and Pre-Split Spacing


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Current pre-spli t spacing = 2.2 m

Dymanic method=1.8-1.9 m

Application of dynamic method, case study n1

Pre-split design in argilic andesites


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BANCO 480

BANCO 495


BANCO 465

Case study area

Current pre-split design

Filtro de precrote 65%


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Pre-split design in chlorite metandesites

Current pre-spli t spacing = 1.8 m

Dymanic method=1.2 m


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Current pre-split design

Case study area


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Pre-split design in Qz-Sericite Granodiorite

Current pre-spli t spacing = 0.9-0.7 m

Dymanic method=1.3 m


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Results with S=1.8 m

Results with S=1.3 m (Dynamic method)

Design achieved with S=1.3 m


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The new method proposed considers Vp and Ed as a relevant variables into the

borehole pressure decay factor. Therefore geotechnical properties are contemplate.

Geotechnical properties of rock massif can be evaluated by cross hole techniques

(Vp).

The spacing of pre-split holes can be obtained for different geotechnical domains

follow the dynamic method.

Dynamic methods demonstrates Improvements in bench quality and bench design

achieved.

Conclusion


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T H A N K Y O U

06 nuevo método para obtener un criterio de diseño optimo de precorte ... ppt asiex 2012

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