A
PRESENTATION
TITLED ON
SLOPE STABILITY IN OPENCAST MINES
PREPARED BY:
MAMTA JASWAL (090610122047)
Government Engineering College Palanpur
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Slope Failure is usual phenomenon in
opencast mines as observed and noticed.
The objective is to find out reasons of slope
failure in mines and to control the slope
failures by taking remedial measures.
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The presentation is addressing the issues
which are responsible for slope failure and
find out the factors for slope failures leading
to severe losses in mines.
The study incorporates design of slope taking
into consideration a geotechnical property of
strata and suggest remedial measures to
mitigate slope failures in lignite mines which
can be useful to various mines in Gujarat.
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Factors affecting slope failures are:
Excessive build up pressure of pore water
pressures within the fill.
Placing the toe of a fill on unstable ground
beyond the edge of the bench.
Placement of soil at slopes too steep to
remain stable and possibly,
Reduction in soil shear strength due to rapid
soil weathering caused by excessive seepage.
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Dynamic loading caused by blasting, earthquake,
etc. shear stresses are momentarily increased as
a result of vibration in the rock mass.
The most serious problem in rock slope failure
often is concerned with the location, orientation
and properties of structural discontinuities in the
rock mass.
If the blasting is not done properly, there shall be
chances of formation of ledges in the high wall
and chances of slope failure becomes high.
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Planar failure
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Circular failure
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Wedge failure
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Toppling failure
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Failure due to sheared and decomposed rock.
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The geo mechanical information which are
most relevant to the slope stability are shear
stability are shear strength or cohesive
strength, the angle of friction and the density
of rock mass.
The angle of slope of bench should be either
equal or less than the angle of repose of the
bench rocks.
In competent rocks angle of slope of high
wall benches varies between 65°-80°.
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The slope of angle depends upon the plane of
weakness, orientation of bedding planes, etc.
however the slope wall should not be retained
by the artificial means at an angle in excess
of it’s natural angle of repose.
Bench slope may be stabilized by practicing
controlled blasting (pre-splitting, smooth
wall blasting, etc).
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Supporting of the high wall slopes may
control the failure of slopes. The following
are the main supporting systems for high wall
slopes:
Toe ditches
Fences
Nets
Bolting
Anchoring
Shotcreting
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Terrestrial laser scanner ground based LIDAR
i.e. light detection and ranging instrument to
obtain a 3 dimensional point cloud for a
barren slope area.
The data of point cloud were scanned twice
on two different dates to analyze the
deformation of slope.
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Thus, overlapping of the two scanned data
sets on same local co-ordinate system shall
attain relative slope displacement.
The differences between two data sets can be
predicted using following procedures:
(1) Using triangulated irregular network
(2) Importing two triangulated irregular
network on the same co ordinate system.
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(1) data acquisition
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(2) data processing
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(3)data analysis.
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It is fully portable sensor.
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Range up to 1000m.
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It doesn’t require any prism commonly used in
surveys.
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Thousands of point are monitored rapidly.
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No need of fixed installation.
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It can access over steeply dipping slopes, critical
zones prone to hazards.
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It cant access any sort of vegetative slope.
Laser cant be worked on high absorption
surface like coal due to less or zero
reflectivity.
It does have limit like field of view, range.
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Thank You...