5 Mine Surveying

Mining Surveys

Mine Surveying

Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry

GE 12 – General Surveying II

- Includes geo-physical surveys for mineral and energy resource exploration. - Utilizes the principles for control, land, geologic, and topographic surveying to control, locate and map underground and surface works related to mining operations. - Includes underground surveying as well as surface operations associated with underground work and open-pit mining. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


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Terminologies Minerals – refers to all naturally occurring inorganic substance in solid, gas, liquid, or any intermediate state including energy materials such as coal, petroleum, natural gas, radioactive materials, and geothermal energy. Outcrop – exposed part of the vein. Adit – a horizontal or nearly horizontal passage driven from the surface for working or dewatering a mine





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Terminologies

Terminologies

Shaft – a vertical or inclined excavation in a mine extending downward from the surface or from some interior point as a principal opening. Cross cut – a horizontal opening driven from the shaft to a vein across the course of a vein in order to reach the ore zone. Collar – the term applied to the timbering or concrete around the mouth or top of a shaft Stope – underground “room” or working area from which ore is removed. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


Back – the top of a drift, cross cut or stope. Also called a roof. Back fill – waste rock or other materials used to fill a mined out stope to prevent caving. Bedded deposit – an ore deposit of tabular form that lies horizontally or slightly inclined and is commonly parallel to the stratification of the enclosing rocks. Sump – an excavation made at the bottom of a shaft to collect water. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


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Terminologies Level – horizontal passage or drift which starts from shafts and are commonly spaced at regular intervals in depth. Either numbered from the surface in regular order or are designated by their actual elevation below the top of the shaft. Headframe – a construction at a top of a shaft which houses hoisting equipments. Raise – a vertical or inclined opening driven upwards in ore from a level. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry




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Terminologies Foot wall – the wall or rock under a vein or other steeply inclined mineral formation. Hanging wall – the wall or rock on the upper side of steeply inclined deposits. Winze – a vertical or inclined opening driven downwards (sunk) from a point inside the mine for the purpose of connecting with a lower level. Sill – synonymous with floor. Waste – mined rocks that do not contain minerals. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry




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Terminologies

Terminologies

Cage – an elevator for workers and materials in a mine shaft. Chute – a channel or trough underground, or inclined trough above ground, through which ore falls or is shot by gravity from a higher to a lower level; can also be spelled shoot. Cone – a funnel-shaped excavation located at the top of a raise, and it is used to collect rock from the area above. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


Drawpoint – a place where ore can be loaded and removed; it is located beneath the stoping area, and gravity flow is used to transfer the ore to the loading place. Entry – manway, haulage, way, or ventilation way below the ground, of a permanent nature. Face – end wall of a drift or cross cut or of bedded deposit. Gangway – a main haulage road underground. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


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Terminologies Finger Raise – used for transferring ore; the usual arrangement is as a system of several raises that branch together to the same delivery point. Gangue – undesired minerals associated with ore. Grizzly – an arrangement that prevents oversized rocks from entering an ore transfer system; consists of a steel grating for coarse screening or scalping. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry




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Terminologies Ore – a mineral deposit that can be worked at a profit under existing economic conditions. Ore pass – vertical or diagonal opening between levels to permit the movement of ore by gravity. Pillars – natural rock, or ore supports, left in slopes to avoid or decrease the roof subsidence as mining progresses. Prospect – a mineral deposit for which the economic value has not yet been proven. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry




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Terminologies

Terminologies

Rib – wall in an entry; can also be called as wall. Slot – a vertical or inclined ore section that is excavated to open up for further stoping. Tunnel – a horizontal or nearly horizontal underground passage that is open to the atmosphere at both ends. Ramp – an inclined underground opening that connects levels or production areas; usually driven downward. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


Vein – thin deposit of minerals between definite boundaries. Strike – the line of intersection between vein and the horizontal plane. Dip – angle of inclination of the vein from the horizontal plane. Drift – a horizontal opening in or near a mineral deposit and parallel to the course of the vein or long dimension of the deposit. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


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VEIN



10

VEIN

ike str

Drift

11

N

ike

Bearing of strike

str

Dip

e

ik str

Bearing of drift

Drift

Drift

grade of drift

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Dip and Grade of Drift

Solving for Dip

strike

B

A

D sinθ = BD/AD

θ

B

D

tan dip = CD/BD

C

tan dip = grade of drift sinθ D

A grade of drift

grade of drift = CD/AD Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry



C


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examples

exercise

A vein has a strike with bearing N 27o 30’ E. A drift in the vein having a 3% grade is due N 30o 20’ E. Solve for the dip of the vein. Answer: dip = 31o 15’ 14.11” A vein of ore has strike of N 45o00' E. The vein dips at angle of 15o. Determine the bearing of the drift of the vein having a grade of 6%, drilled NE relative to the strike. Answer: bearing of drift = N 57o 56’ 22.41” E

Please bring out a piece of paper.  A vein facing north-west has a drift driven N 67o W in the plane of the vein on a grade of 3%. If the vein dips at 5o 15’ 53.08”, what is the bearing of the strike of the vein? (Answer it in 5 minutes) Answer: bearing of the strike: N 48o W





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Solving for Strike and Dip using Boreholes

d su groun

rface

BOREHOLES – any narrow shaft bored in the ground, either vertically or horizontally , constructed for extraction of water or other liquid or gases, as part of a mineral exploration, geotechnical investigation and environmental site assessment.





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d su groun

rface

d su groun

rface

n

an Pl

e

of

i Ve

• a 3D coordinate system is being chosen such that its z-axis passes thru the highest point (C)

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d su groun

rface

d su groun

z

C

e an l P x

rface z

C

of

• the line connecting the highest two points should lie on the yz plane

in Ve

C'

B B'

• choose the lowest point (in this case A) to lie on the xy plane (horizontal plane), z = 0

n

an Pl

of

i Ve

e C'

B B'

x D

A

y

To solve for the strike, extend the line of the 2 highest points to the horizontal plane. It intersects the plane at a point, D.

A

strike

y

Here, points A and D lie on the horizontal plane and the plane of the vein

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θ = azimuthAB – azimuthAC φ = azimuthCB – azimuthAB α = 180 - θ - φ

sine law: C'B' = (AC')sinθ / sinφ AB' = (AC')sin α / sinφ similar triangle

sine law:

DB'

DB' DA

cosine law: (DA)2 = (DB')2 + (AB')2 – 2(DB')(AB')cosσ bearing of strike = azimuthAB + β

C ' B ' BB' CC ' – BB ' σ = 180 – φ

example Three boreholes were sunk to a vein of ore. The depth of the three holes at the points A, B, and C, and the surface measurements connecting them are: Elevation of surface @ A = 4750 ft ; depth of hole = 3500 ft Elevation of surface @ B = 4920 ft ; depth of hole = 2860 ft Elevation of surface @ C = 4790 ft ; depth of hole = 2080 ft AzimuthAC=60o22‘(from South); AzimuthAB=80o30‘(from South); AzimuthCB=140o20’ (from South) AC = 1320 ft (horizontal distance) Find the strike and dip of the vein. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


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Point A B

elevation @ surface

depth of hole

elevation @ vein

zcoordinate

4750

3500

1250

0

4920

2860

2060

810

θ = azimuthAB – azimuthAC = 20o 8’ φ = azimuthCB – azimuthAB = 59o 50’ α = 180 - θ – φ = 100o 2’

4790

2080

2710

C'B' = 1320 * sinθ / sinφ = 525.53 ft

AB' = 1320 * sin α / sinφ = 1503.43 ft

similar triangle

sine law: 654.89 1918

DB'

1460

525.53

σ = 180 – φ = 120o 10’

810

1460 1503.43 = 17o 10’ 11”

elevation @ vein = elevation @ surface - depth of hole

z – coordinate = (elevation @ vein)i - (elevation @ vein)min Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry

525.53 ' 810 ' 1460 – 810 = 654.89 ft

= sin-1(0.2952) = 17o 10’ 11”

C

sine law:

654.89

cosine law: (ΔAB’D) (DA)2 = (654.89)2 + (1503.43)2 – 2(654.89)(1503.43)cosσ = 1918 ft


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bearing of strike = azimuthAB + β = 80o 30’ + 17o 10’ 11” = 97o 40’ 11” = N 82o 19’ 49” W (from A)

sin β = EB’ / AB’ EB’ = AB’ sin β = 1503.43 sin β

Mine Survey Limitations

= 443.82 ft tan(dip) = BB’ / EB’ = 810 / 443.82 dip = tan-1 (1.83)

= 61o 16’ 50”

AzAB= 80o 30’

Special conditions in the underground surveys: 1. Limitations of space: small instruments of special designs with extension tripod legs or suspension rods are used.

dip 810

= 17o 10’ 11” E

2. Very short and very steep (or vertical) sights: special methods of observations are necessary with particular care to avoid the accumulation of excessive errors in measurements.

N



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Mine Survey Limitations Special conditions in the underground surveys:

Eccentric Telescopes

3. Instrument station markers are on the roof: modification of the traverse procedures.

These are small telescopes attached to the main telescope to correct the value of the measured angles.

4. Darkness: special arrangements for illumination of both the instrument and target.

Eccentricity (e) – distance between the eccentric telescope and the main telescope.

5. Slope distances: vertical angles are measured and three dimensional coordinates of instrument stations are determined. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry




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Top Telescope

example

β=α–θ where: θ

= tan-1(e / BD)

(AD)2 = (BD)2 + e2 V = (AD) sinβ

elevD = elevA – V

- a small telescope mounted on top a transit or theodolite.

Point D is sighted using a theodolite with a top telescope at an angle of –65o 23'. The distance from the top telescope to point D is 100m. The elevation of point C (station occupied) is 150m and the eccentricity of the instrument is 0.05m. Find the correct vertical angle and the elevation of point D if the height of the instrument is 1.5m. answer: corrected vertical angle = 65o 21’16.87” elevation of pt. D = 60.61 m Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry


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Side Telescope

example A side telescope was used to obtain angle and distances. The distance to point B is 10.5 m and it was turned clockwise 63o25' to sight point A which is 14.3 m from the side telescope. If the side telescope's offset is 0.20 m from the main telescope, what is the correct horizontal angle between A and B?

- a small telescope attached at the side of a transit or theodolite.

θ1= tan-1(e / OA') θ2= tan-1(e / OB') β = α – θ1 + θ2 (OA)2

(OA')2

e2

= + (OB)2 = (OB')2 + e2


(AB)2 = (OA)2 + (OB)2 – 2(OA)(OB)cos β


answer: corrected angle = 63o 7’ 36.75”



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Underground Traverse: through adits and tunnels

Exercise From the given data, find the corrected vertical angles and the elevation of station X

Sta. Occ.

Sta. Obs.

Vertical angle (using top telescope)

Rod reading

Slope distance(m) (from top telescope to point sighted)

-3.06 X

Z

+ 60o

(Note: negative rod reading means station is on the FLOOR)

Control network of traverses (frequently openend traverses) that must follow existing net of mining workings and excavations.

Executed with the utmost care and are usually independently checked by a second resurvey.

80

e = 0.06 m; HI = 1.3 m; elevZ = 200 m above msl Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry




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Control Network first-order control a) 1 : 10,000 in small and medium-size mines b) 1 : 20,000 in large mines extended over areas of several kilometers in diameter.

Monumentation and marking of points The stations of the horizontal control network are usually marked in the roof (back) or walls of the mining workings.

second-order control 1 : 5000 third-order control 1 : 1000



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Angle and Distance measurements

Traverse Computation

The old-type vernier transits, although still in use, are being replaced by much smaller and lighter theodolites with the optical micrometer readout.

Coordinates of underground stations should be calculated in the surface coordinate system so that positions of details on the surface can be analytically correlated with individual levels and sublevels of the mine.

Steel tapes are still the most popular tools in distance measurement. Light weight electronic distance measurements (EDM) instruments are also becoming popular as long as they are fire- and damp-proof.

First-order and second-order underground traverse loops should be simultaneously adjusted by the method of least squares.





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Traverse Computation

example

Remark: In long traverses with many stations, the positional accuracy of the last point may be smaller in a traverse with measured angles, compared with a traverse with azimuths measured, even when the angles are measured with a much higher accuracy than the azimuths. If NA = 10,000 and EA = 10,000, find NE and EE.





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Mine orientation surveys: basic principles and classification Very often, the only access to the mine is by way of vertical shafts, therefore, direct traversing from the surface is impossible. –

Shaft plumbing with two or more plumblines in one vertical shaft. • •

–

Shaft-plumbing procedure: Plumblines P1 and P2 serve as intermediate traverse stations between points

Problem: solve for orientation angles β1 and β2 which must be determined indirectly.

Weisbach method Quadrilateral (Hause) method

Shaft plumbing through two or more vertical shafts with one plumbline in each shaft.





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Weisbach Method (triangle method) The orientation angles, β1 and β2 are determined from measurements of: - the angle α1 and distance a, b1

Weisbach Method (triangle method) Angles β1 and β2 are calculated from the simple trigonometric function:

and c1 on the triangle on the surface - angle α2 and distance b2 and c2 in the underground triangle.

The distance a is also measured underground to approximately check the verticality of the wires. The angle α2 is made to the predetermined vertical positions of the wires on the scales (one scale for each wire) perpendicular to the line of sight. To complete the orientation measurements, the angles δ1 and δ2 are measured at stations B and C. Department of Geodetic Engineering Training Center for Applied Geodesy and Photogrammetry




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Hause Method (quadrilateral method)

Hause Method (quadrilateral method)

The following values are measured in the quadrilateral method: angles δ1 , δ2, γ1 and γ2 and distance P1P2 and CD in the figure.



The coordinates of P1 and P2 are calculated in the local system by simple intersection from the base CD.



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Vertical control surveys and leveling Special steel tapes of lengths up to 1000 m stored on large reels are available for transfer of heights from the surface to the underground workings.

Problem Surface Coordinate System STA. NORTHING A 1690002.675 B 1690012.198 STA OCC

OBS A P1 P2

B

Underground Coordinate System LINE DIST. (m) C-D 12.505 STA OCC C



OBS D P1 P2

EASTING 506999.507 507006.262 HOR. ANGLE (clockwise) 0-00-00.00 217-33-59.07 253-36-11.13

•

A mine orientation survey was performed using shaft plumbing with 2 plumblines in 1 vertical shaft and the following data were gathered in the field:

DIST (m) 11.676 8.398 5.728

Assumed AZIMUTH 270-00-00 HOR. ANGLE (counterclockwise) 0-00-00.00 51-57-27.00 76-55-53.00


STA OCC D

OBS C P2 P1

HOR. ANGLE (clockwise) 0-00-00.00 46-21-05.00 61-16-10.00


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For practice

References

• From the results of the previous problem, perform a check by using the formulas discussed (Hause method). Verify if the coordinates of A, B, P1 and P2 that you will get using the solved coordinates of C and D is correct. 



• Anderson, J. Mikhail, E. Surveying Theory and Practice (7th ed.). New York: McGraw-Hill Science, 1998. • Davis, R., Foote, F., et al. Surveying Theory and Practice. New York: McGraw-Hill Book Company, 1981.



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Thank you for listening!



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5 Mine Surveying

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