STRESS MAPPING FOR RE- ORIENTATION OF GALLERIES IN

PVK-5 Incl.

Dr.D.N.SHARMADy.General Manager(Geo)

Exploration Division / RG1

• In PVK mine, King Seam workings reached 400m depth.

• Thickness of the King Seam in the study area is about 6.50m with a gradient of 1 in 8.

• King seam was developed in the Top Section upto 116 Level, withSandstone as immediate roof.

• Since there is a problem with sever seepage of water along sandstone roof , an attempt was made to leave about 3.50m seam portion in the roof.

• In the changed working section, another problem of severe roof failures in Level galleries cropped out.

1. PROBLEMS IN KING SEAM

2. STRESS MAPPING IN QUEEN SEAM

With a similar problem in overlying Queen Seam workings that is beyond 110 Level at a depth of 350m, Stress mapping was carried out, during June 2004. The inferences of those studies were-

The Major Principal Stress axis inferred from most prominent Joint set (J1) is perpendicular to Level galleries are contributing for instability of level galleries.

Minor Principal Stress axis inferred from least prominent Joint set (J3) is parallel to level galleries.

Conversely, Dip galleries are stable as they are almost (with about 5 degrees) parallel to the Major Principal Stress axis.

Further, these findings were closely matching with that of Stress Orientation established earlier in the Queen Seam of adjacent VK-7 Shaft through similar Stress Mapping technique.

CONTOUR DIAGRAM OF JOINTS PLOTTED ON EQUAL AREA PROJECTION,LOWER HEMISPHERE,

QUEEN SEAM (100 JOINT POLES)

DIRECTION OF STRAIN ELLIPSOID DEVELOPED IN QUEEN SEAM

3. STRESS MAPPING IN KING SEAM

1. Stress mapping is carried out in the present study area in King Seam.2. The workings crossed 400 m. depth line and approaching the F16 Fault

(throw 20m) in the dip side property. 3. The details of structural features mapped are as follows -

SL.NO STRUCTURAL FEATURE NO.OF READINGS. MEAN TREND

1 FACE CLEAT140

N550E

2 BUTT CLEAT N350W

3 MOST PROMINENT SLIPS40

N450 E

4 LEAST PROMINENT SLIPS N650E

5 MOST PROMINENT JOINTS27

N550E

6 LEAST PROMINENT JOINTS N650E

3. STRESS MAPPING IN KING SEAMContd…

4. The causative factors of unstable roof conditions are due to :

• The most prominent Slips S1 aligned to the greatest principal stress direction (N450E) is responsible for the roof instability confined to level galleries.

• Roof strata consists of thin layers and leading to failure in level galleries with an indication of "Gutter roof". Trend of the "Gutter roof" ,largely helped to confirm the orientation of principal stress in the study area.

• As workings are enveloped by Faults, sympathetic slips developedand contributed for unstable roof conditions.

• These findings are closely matching with that of Stress Orientation established in the overlying Queen Seam.

FACE AND BUTT CLEAT

SLIP IN THE PILLAR SHOWING DISPLACEMENT OF BANDS

J1 JOINT EXPOSED IN THE FLOOR

4. ROCK MASS RATING (RMR)RMR classified the roof of working section of King Seam (Bottom Section) as "FAIR“ with a rating of 41, where 40 is border of “Poor”and “Fair” rock.

“ROOF GUTTERING” IN THE CENTER OF LEVEL GALLERY BEFORE RE-ORIENTATION

5. NUMERICAL MODELLING BY CIMFRNumerical modelling was taken up by CIMFR and the following conclusions and recommendations are made:

1. The magnitude of major and minor in situ horizontal stresses in King seam in the study area are found to be 7.15 Mpa and 3.68 Mparespectively.

2. The direction of the major in situ horizontal stress is found to be along N 450 E , which is almost perpendicular to the level galleries.

3. Keeping the above directions and magnitude of in situ horizontal stresses in view, level gallery can be driven along N 850 E toE 50 S (with a stress point of view).

6. ORIENTATION OF GALLERIES REFERENCE TO PRINCIPAL STRESS

N

N 7

° E

N 1

0°

E

N 2

4° E

N 55° E

N 69° E

N 62° W

N 47° W

F5R

E-O

RIE

NTE

D-1

DG

F18

F10 & J1

& FC

F9

F16

RE-ORIENTED-1.LG

S1N 4

5° E

N 65° E

S2 & J2

N 35° WBC

N 73° E

ORIGINAL DG

N 24° W

OR

IGIN

AL LG

INDEX

N 45° W

1

N5

°WR

E-O

RIE

NT

ED-2

DG

N85°ERE-ORIENTED-2. LG

S1 MOST PROMINENT SLIP

J1 MOST PROMINENT JOINTS2- NEXT PROMINENT SLIP

J2 NEXT PROMINENT JOINT

FC- FACE CLEATBC-BUTT CLEAT

1- MAJOR PRINCIPAL STRESS 3- MINOR PRINCIPAL STRESS RE-ORIENTED-1 DIP GALLERY

RE-ORIENTED-1.LEVEL GALLERYORIGINAL DIP GALLERYORIGINAL LEVEL GALLERY

RE-ORIENTED-2 DIP GALLERYRE-ORIENTED-2. LAVEL GALLERY

EW

3

N/55

N/49

N/46

N/48

N/51

N/46A

N/50

N/29

1 IN

5.1

9

TS T

O K

S

108L96L

15D

11D

7D

4D

1D

85L

90L

533.50

558.2

0

527.50

543.45

552.06

549.55

569.30

569.

60

N/30

N/47

85L

82L

MIDM

WD

88L

TO KS/TS1 IN 10

LEVE

L D

RIFT

LEVE

L DR

IFT

LEV

EL D

RIFT

1 IN

6

1 IN

10

1 IN

10

1 IN

10 1 IN 10

1 IN 10

1 IN 6.7

1 IN

10

2.4M

0.5M

3.2M 0.7M 0.

3M0.2

M

1.2M502.8

7

0.8M

1.3M

23D

4M

3.8M

1.2M

25D

27D

30D

92L

578.

47

F.K.S...... 447.69(5.20)

557.

40

485.36

535.

98

565.

50

20D

20D

22D

97L

95L

L.T. LINE

HAULER ROOMSURFACE150 HP

816.13

816.03B.M...816.54 M

OFFICE

No 5B INCLINE

11D

7D

TO KS/TS1 IN 10

TO KS/TS

1 IN 10

TO KS/TS

1 IN 10

1 IN

4 1

IN 5

M

ID

MW

D

5B AIR SHAFT

110L

25D

23D

21D

20D

1

IN

5.1

9

TS T

O KS

512.

490

DIA: 6.5M

1.2M

3.2M

3

2A

2

33 K.V. TRANSM

ISSION LINE

60m B

ARRIER

60m BAR RIER

60m BARRIER

60m

BAR

RIE

R

1 .20M3.20M

501.

595

0.60M

482.

49

487.

44

483.

20

508.

08

495.

53

494.

44

DEPTH :292M

PVK SHAFT

F10

F10

D/H

16D

12D

112L BELT LEVEL

487.

04

10D9D

S/22

472.2

9

0.40.250.350.1

0.22.0

0.1M0.25M

471.7

4473.0

8

8D

472.6

4

800.34

803.06

805.16

810.05

T E L L A

V A G U

807.68 HFL

803.72

805.00 HFL

HFL

WIT

H I

N TH

E N

ALLA

H

T E L L A V A G U

796.60

797.27

798.

05

DIVERTED

6D

4D

2D

0R

115L

482.5

2

488.0

7

479.6

9 488.2

8

492.6

4

464.0

85

462.9

4

462.4

0

458.7

7

500.6

86

UG B.H. TO K.S.

N82°W

N8°E

S5°E

S85°

W

N0 200

43D

45D

116CXCUT

412.533

419.193

404.653

400.388

398.573

415.898

533

.339

536.

670

539

.870 543

.450 546.

280

543.

53

537

.45 540

.57

530.

879

534

.18 53

7.37 54

0.5

253

4.00

530.

83

528

.26

5D

3D

552.

03 555

.10

551.

65

550

.44

548

.34

546

.035

49.1

2

542

.67 544

.78 546.

92

554

.30

540

.62

538.

53

535.

85

532

.0

548.

42

544.

86

422.05426.84

420.55

413.39415.19

409.25

404.69

426.55

JH

GH

GH

47D

49D

430.835

424.335

418.505

408.265

420.035

428.27

558

.55 56

0.35

556

.85 55

8.8

4

554.

17

549.

535

552.

38

544.

145

542

.42

536

.285

538.

825

38D

521

.984

12D

9D

517

.53

4

519.

614

510

.67

451

6.5

79

513.

749

405.596

1.8m

526

.869

524

.914

518.

859

424.11

403.156

410.266

533

.339

523.

924

524.

984

7D

40D

38D

116BXCUT

GH

B.H. No..A/326F.K.S...... 541.60(5.35)

DEPTH....310.00

28D

GH

GH

GH

506

.53

504.

38

488.

75

473.

67

512.8

38

509.5

88513

.043

524.3

18

519.0

8852

2.63

511.6

56

504.9

36

502

.09

505

.89

9

497

.899

494

.804

483.

759

BELT ROAD

434.

00

419.

61

396.

96

401.

42

396.

54

405.

72

394.0

394.36

391.43

489.2

3

481.0

4

490 .59

466.7

5

457.2

6

454.6

1

475.9

2

22D

3.5m

410.

41

418.

33

393.

34

395.

87

3.5m

4.5m

4.5m

494.8

8495.5

3

24D

26D

23D24D

26D

28D

30D

32D

34D

36D

GH

452.

72459

.66

457

.95

458.

291.6

2

0.70.8 1.20.6

0.4

0.8

0.7

0.6

22

UG B.H. TO K.S.

501.3

2

494.9

9

471.

03

469

.04

467.

46

452.

21

107L

488.41

0.8

0.80.7

0 .7

441.

9743

5.94

431.

69

424.

80

420.

23

JHw

96L

0.6

0.4

B.H. No..A/324S.L.... .....802.21

DEPTH....365.00DIA.. ......10CM

F.K.S...... 444.71(7.70)

484

.50

478

.48

487

.26

461.

73

460.

41

458.

0544

9.47

506.53

494.6

6

6.5m

PANEL No.S-21

1.4m

1.4m

0.5m

0.5m

0.2M

0.3M

0.3M

0.45M

12D

16DN 18D

20D

119L

15D

16DS

BELT LEVEL

BELT DIP

BELT

DIP

407.

29

436.

28

403.95408.18

415.50

412.01

1m

120L 120L

120L

22D

GH

GH

GH

GHGH

GH

HAULAGE DIP

HAU

LAGE

DIP

394.59

399.34

404.46

397.7 397.69

403.

48

404.

51

413.

67

425.

0943

1.97

437.

97

447.

48

400.

5

403.

5340

0.92

122L

GH

GH

122L

16BD 1.6m

2m

1.6m

16DN16AD

18D19D

94L

91L

5D

3D

1D

MID

122L123L

397.36

395.55

392.38

400.

47

403.

79

410.

51

1m

1m

1.6m

D/H

E/HD/H

13D

EH

END LESS HAULAGE

END LESS HAULAGEJ/H

123L

392.62

2.5m

394.

18

400.

47

395.

68

408.

51 410.

23

417.

7142

3.33

428.

35

474.6

847

8.52

463.1

0463.35

449.2

3

439.20

527.47

474.

76

465.

37

3

2A

2

3

2A

2

B.H. No..A/342

FKS-382.10

B O

U N

D A

R Y

3

2A

2

FKS-....429.39

B.H. No..A/306

P BORE HOLEDEPTH....240DIA........10CM

B.H. No. .A/320

DEPTH....310.00

F.K.S......516.23(5.35)

B.H. No..A/323

DEPTH.. ..367.00

F .K.S......449.25(6.80)

B.H. No..A/286

DEPTH..365.93

F.K.S.... 448.68(6.86)

B.H. No.. A/285

DEPTH....407.55

F.K.S...... 403.80(5.45)

B.H. No..KSB-7

DEPTH....431.92

F.K.S......409.61(6. 05)

B.H. No.. A/311A

DEPTH....375.00

B.H. No.. A/316

DEPTH....435.00

F.K.S......383.44(5.60)

B.H. No..A/115DEPTH....396.24

F.K.S......520.65(5.37)

B.H. No. .KSB-5DEPTH....339.38

B.H. No.. A/119DEPTH....262.1

B.H. No..KSB-14S.L.... .....804.07DEPTH....153MDIA.. ......10CM

B.H. No..A/319DEPTH....236

B.H. No..A/338DEPTH....216.50

B.H. No..A/337DEPTH....216.50

B.H. No..A/336DEPTH.... 213.00

B.H. No.. A\174

B.H. No.. A\178

B.H. No.. A\175

DEPTH....159.50

B.H. No.. A\157

DEPTH....161.85

DIA...... .....15CM

DEPTH....115.06

NO 1 ... 727.44 (19.58)S.L........ ....798.84

DIA...........15CM

DEPTH....65.68

NO 1SEAM ...780.210 (13.72)S.L.. ..........803.070

B.H. No. . A\183 DEPTH....56.80

B.H. No.. A\118 DEPTH.... 169.840

B.H. No.. A\185 DEPTH....53.03

B.H. No.. A/313

DEPTH.... 420.00

F.K.S......391.85(5.90)

B.H. No..A/350 (MPBX)DEPTH....285.00

B.H. No..A/340

462.3

9

447.36

439.

57

442.98

454.26

525.55

430.

944

441.

12

429.12434.183

447.9

7

453.6

4

3M

2M

0.8M

115L

117L

115L

117L

419.07

417.23

422.

71

426.

23

454.

9244

3.60

434.

68

416.

36

119L

417.

23

412.

25

1.4m

1.2m0.4M

0.4 1m

1.4m

1.4m

0.5m

0.65m

0.6m

0.8m

562

.13 56

3.38

559.

72

539.

48 541

.26

563.

658

561

.313

565.

412

567.

242

567

.102

562.

972

558

.625

554

.563

549

.663

547

.2285

50.2

9855

5.50

3

570

.53

7

566

.498

545.

818

113L

423.031

431.351

427.746

421.036424.486

416.911419.021

PANEL STD. ON 20-05-11

STABLE ROOF IN THE LEVEL GALLERY AFTER RE ORIENTATION

7. SUMMARY AND CONCLUSIONS

1. PHYSICAL MAPPING LARGELY HELPED TO DERIVE STRESS ORIENTATION IN THE STUDY AREA TO BE N450E.

2. THE DATA IS VALIDATED WITH THAT OF OVERLYING QUEEN SEAM AS WELL AS ADJACENT BLOCK i.e. VK-7 SHAFT.

3. FURTHER IT IS VALIDATED WITH NUMERICAL MODELLING DATA. 4. FINDINGS OF ALL THE ABOVE STUDIES ARE IN GOOD

AGREEMENT WITH EACH OTHER.5. BASED ON THE RECOMMANDATIONS (to drive Level Galleries in

N850E) OF ABOVE STUDIES, STABLE ROOF CONDITIONS COULD BE ESTABLISHED.

******