Mining Seismic Systems

8/12/2019 Mining Seismic Systems

1/20

Mine Seismicity

A brief Over


2/20

Basic Concepts

What is rockbursting and mine seismicity? What causes it?

What are it's effects?

How is it monitored?

What can be done about it?


3/20

Definitions

A seismic eventis a dynamic stress wavecaused by the fracture or deformation of arockmass.

A rockburstis generally considered to be aseismic event that results in visiblerockmass damage.


4/20

Seismic Source Mechanisms

Shifting on Geological FeaturesThe movement of two or more bodies of rock of

different composition.

Dykes Inclusions Faults


5/20


Seismic activity caused by the stresses of underground

mining. Local rock mass failure or deformation Crushing or shearing in pillars

Stress Related Failure


6/20



7/20

Locating the Seismic Source

Is found using thearrival times of the S

and P-Waves

Can be very difficult ifthe seismic sensors arepoorly located orimproperly set up


8/20


STOPE

S


9/20



10/20



11/20



12/20


Locations with a higher density

of events generally are under

higher amounts of stress This information can be

interpreted to help develop plans

to prevent production loss and

damage to the mine


13/20

Seismic Detection Equipment

Geophones/ Accelerometers

Geophones record groundmovement mechanically

whereas; Accelerometers are electronic Both have

advantages/disadvantages

The MP-250 Very first commercially

available seismic monitoring

system Analog recording system Included a loudspeaker Didn't show waveforms


14/20


Modern Seismic

Systems Digitized waveforms

Is able to provide the location ofseismic events

Parameters such as magnitude

and energy are automatically

calculated Connected to a computer display

Above-Ground systems Can be used when

underground monitoring isn't

practical/possible Is normally much harder to

maintain Prone to lightning strikes

S i i D i E i


15/20


G d S t


16/20

Ground Support

G d S t


17/20

Ground SupportRockburst Damage Mechanisms

Roles of Different Types of Gr

Support

G d S t


18/20

Ground Support

Cone

BoltsSplit Sets

Very High Yield Designed Specifically for

rockbursting conditions High tensile strength allowing

for very effective reinforcement

Relies on friction for support Relatively inexpensive

compared to other bolt types

such as cone bolts and swelle

G d S t


19/20

Ground Support


20/20

Content Covered

What is rockbursting and mine seismicity?

What causes it?

What are it's effects?

How is it monitored?

What can be done about it?

All pictures are property of Prof. Marty Hudyma

Documents

Mining Seismic Systems