strike dip rise longwall panels

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Critical Review of Working Strike Longwalls Versus Dip-Rise

Longwalls

U Siva SankarSr. Under Manager,

Email;[email protected]@gmail.com

Working layout of GDK -10A Incline

Group 2 Group 1 Group 3

2

Orientation of Panels

With True NorthPanel

N 670 E

N 110 to 26 0 W

Dip Rise Panels(Strike Face)

Strike Panels(Dip-Rise Face)

� Principal Stress Direction of ADRIYALA & GDK-10A is NNE 240

� At Adriyala, M/S MESY India conducted 17 successful hydrofrac tests for the determination of a stress-depth profile for the depth range between 77 m and 522 m.

� For all of the 17 hydrofrac tests the orientation of the induced fractures was determined by impression packer tests.

� The mean azimuth of the vertical fractures was determined as N (24 ± 14) degrees (NNE)

� Mean stress-depth relations for the minor and major horizontal stresses and verical stress

�Major Horizontal stress vertical Stress varies from 1 to 1.2 times vertical stress at 300m to 500m depth

3

Orientation of Panels

Gradient of Gate Roads and Face

Gate RoadsLongwall FacePanel

1 in 50 to 1 in 60

1 in 6 to 1 in 6.2

1 in 6 to 1 in 7Dip Rise Panels(Strike Face)

1 in 20 to 1 in 25Strike Panels(Dip-Rise Face)

4

Support System

• MECO- 4x800 tonnes IFS powered Roof Supports are being used.

• Face sprags are being used in dip – rise panels

Creep Control

Monitoring

Staggering

Even with negligible monitoring, no major movement of face machinery was observed.

Regular Monitoring is Required

MG is Kept ± 2m ( < 10

swing )of TGMG is Kept 10 to 15 m (40 to 6 0 swing ) in advance of TG

Dip –rise Panels(Strike Faces)

Strike Panels(Dip –Rise faces)

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Weighting Details

Intensity

Periodic Weighting

Main Weighting

Reduced (C30 to C75 is Supports Yielding Zone)

More (readings)(C30 to C80 is Supports Yielding Zone)

Regular at an interval of 5 to 28 m, with an average interval of 17 m.

Regular at an interval of 7 to 25 m, with an average interval of 16 m.

55.10 m (Panel # 3B) & 53.00 m (Panel # 3C)

72.00 m (Panel # 3A)



Face, Roof and Gate Roads Stability

• Slabbing in face is more in Strike face compared to dip-rise face and it was 2m ahead of tip of canopy during periodic weightings. (Direction of cleavage planes plays role)

• Cavities were also frequent at the time of weightings in strike faces compared to dip – rise faces

• Cavities & Slabbing in Face was reduced & Safety was also improved with the introduction of Face sprags in strike faces.

• In strike Panels guttering was observed in gate roads.

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Horizontal stress - Longwalls

• Horizontal stress can not pass through gob area or broken or collapsed roof; therefore zones of stress relief and stress concentration are created

• Their location depends on panel orientation, direction of retreat and sequence of extraction

Gate Road Stability with respect to horizontal stre ss (After Mark)

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�Group 1 Panels as the panels are falling stress concentration zone

� while Group 2 strike panels are falling in stress relief zone and

�Group 3 Dip rise panels are falling under stress concentration zone

From the study with AHSM (Analysis of Horizontal Stress Measurement) NIOSH software

Drainage

Drainage

Make of Water

Goaf to dip most Sump through dip side level gallery

Goaf to MG out by

Initially observed but after main fall no seepage.

450 GPM – Normal period & 650 GPM –after Periodic Weighting



� Face is Dry and Coal Quality not affected in Strike faces compared to Dip – Rise faces

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Modifications - Strike faces

• AFC Motor capacity was increased from 2x150 kW to 2x250 kW as gravity does not support material transport

• In Main gate Three 2x150 kW Gate belt gear heads were installed for coal transport due to higher lift (≈160 m)

Other Observations • Stoppage of longwall face at the time of

Gate belt Gear head dismantling and Gate belt jointing works( one day)

• Switch train shifting & cables handling is tedious and requires special care. (Cables of 100m additional length required for one time shifting for same length)

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✔Less✕✕✕✕MoreFace Spalling

✕✕✕✕Less Comfortable due to humid condition

✔Comfortable due to dry condition

Ventilation

✔✕✕✕✕

Does not require pumpingNot Good

✕✕✕✕✔

Requires pumpingGood

Water Drainage•During Development•During extraction

✔Easy & shifting can be done daily

✕✕✕✕Tedious & cables handling is difficultRequires one time shifting for every 100m or more

Switch train Shifting

✔Single✕✕✕✕Two or More depends upon liftNumber of Belts required in Main gate

✔Easy✕✕✕✕DifficultLaying & Dismantling of gate belts

✔Less Risky✕✕✕✕RiskyMaterial and men Transport in Gate roads

✕✕✕✕Slushy✔DryGate road condition

✔More✕✕✕✕LessGate road progress

✔Easy✕✕✕✕Moderate DifficultDrivage of Single or multiple Gate roads

Strike PanelsDip Rise PanelsParameters

COMPARISON OF DIP-RISE LONGWALL PANELS WITH STRIKE LONGWALL PANELS

✔Gravity supports✕✕✕✕Gravity does not supportCoal Transport in AFC23

✔Moderate✕✕✕✕LessProduction 22

✔More ✕✕✕✕LessSump to each Cut21

✔Uni or Bi-directional✕✕✕✕Limited to Uni-directional onlySequence of Cutting20

✕✕✕✕More & Difficult✔LessFace Equipment Creep problem & Control

19

✔Less✕✕✕✕MoreWear & tear of face equipment (AFC & Shearer Parts)

18

✕✕✕✕More✔LessLoad on Shearer haulage17

✔Moderate✕✕✕✕LessSafety to workmen16

✔Less✕✕✕✕MoreEmulsion requirement for supports

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✕✕✕✕Moderate✔LessStrata Control Problems14

✕✕✕✕More✔LessPeriodic weighting intensity13

✔Similar✔SimilarPeriodic weighting interval 12

✕✕✕✕More✔LessMain Weighting Span11

Strike PanelsDip Rise PanelsParametersS.No


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1919191911111111

FavourUn-favour

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FavourUn-favour

✔Gate roads need to aligned oblique to stress direction

✔Trunks need to be aligned oblique to stress direction

Alternative to lower effect of Principal stress

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✕✕✕✕More because aligned perpendicular

✔Less because aligned parallelEffect of Principal stress on gate roads

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✔Less because aligned parallel✕✕✕✕More because aligned perpendicular

Effect of Principal stress on Trunks

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✔More or less Uniform✕✕✕✕Non-uniformSubsidence over goaf27

✔Moderate Difficult & safe✕✕✕✕Difficult & UnsafeDealing of Heating or fire Problem

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✕✕✕✕Moderate Difficult✔EasySalvaging & installation25

✔Moderate✕✕✕✕HighAFC Motor Starting Torque Requirement

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Strike PanelsDip Rise PanelsParametersS.No


Production Summary

1795 tonnes per day1011509003C12*

1814810,72510115010303B11*

2090921,33510816010143A10

1701619,38477/90115/13599089

1852361,1266693.5720128

1091532,6208011895577

880358,79178110900116

1285434,41611115855510A5

2113551,57794140850104

2426761,927101150102433

2433756,66310115099022

2330764,14810115098011

Prod/day (T)Total Production (T)No. of chocksFace length

(m)Panel length

(m)Panel No.Sl. No.

* Dip – Rise Panels (Strike faces)

strike dip rise longwall panels

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