The document discusses shaft sinking, including its purpose, methods, and key considerations in the process. It covers various topics such as shaft shape and size, support systems, drilling and blasting techniques, as well as special methods like piling and caisson. Additionally, it addresses factors influencing the selection of shaft location and the construction of walling platforms and lighting requirements.

1. GOVERNMENT POLYTECHNIC NAGPUR
Topic: Shaft Sinking
Submitted by:-
 Shreyash Sakharkar
 Anand Vaidya
 Yogesh Kalmegh
 Yash Fating
 Sanyog Meshram
 Ankit Fender
 Yogesh Dahiwale
 Shubham surnkar
 Suraj mane
Submitted to :-
J. T. Rawan Sir
Department Of Mining And Mine Surveying
(An autonomous institute of Government of Maharashtra)

2. content
 Introduction of shaft, shaft sinking ,its purpose
 Factors for selection of shaft sinking
 Shape & size of shaft
 Shaft centering
 Temporory support
 Permanent support – various methods
 Walling platform
 Lighting in shaft
 Drilling ,blasting & mucking process
 Sinking rider
 Special methods of shaft sinking
 Deepening and widening of shaft
 references

3. Shaft Sinking
 Shaft: A vertical or inclined opening from surface for the conveyance of men, materials,
hoisting ore, pumping water and providing ventilation.
 Sinking: The work in excavating a shaft
 Shaft sinking It may be described as an excavation of vertical or inclined opening from
surface for conveyance of men, materials, ventilation, pumping water, in addition to hoisting
ore and waste rock
 It is also called Shaft Construction or Shaft Mining.
 It is a part of mine development, after the complete development it is used for production of
ore purpose and dewatering of mine sumps

4. PURPOSE OF SHAFT SINKING
 To transport men and materials to and from underground Workings.
 For hoisting ore and waste from underground.
 To serve as intake and return airways for the mine (ventilation shaft).
 To access body
 These shafts are used in applications such as hydro electric projects, water supply, waste
water shafts and tunnel projects.
 Drilled shaft machine is used in such process, where it consists of special type of units
that are used in both stable and unstable

5. FACTORS GOVERNING SELECTION OF
SHAFT POSITION
 Surface consideration:-
1. Configuration of the Surface and land available
2. Convenience of Railway
3. Convenience of Roadways
4. Water Supply
5. Surface Drainage
6. Landslides
7. Running Sands

6.  Underground Considerations
1. Presence of Faults
2. Direction and Amount of Dip
3. Direction of Underground Transport
4. Ventilation
5. General Considerations:
Nowdays, however, if the seams are fairly flat and assuming other condition permit,
the tendency is to fix the shaft near the centre of mine property.

7. a) Shape of Shafts :
 The most common shapes of shafts are : (1) Circular, (4) Elliptical. (2) Square, (3)
Rectangular, and In colliery practice, circular shafts are almost invariably used.
 A circular shaft has the following advantages :
 (1) It is the strongest form to resist heavy rock and water pressure.
 (ii) For a given cross-sectional area it presents the least resistance to the passage
of air.
 (ii) It is best suited to sinking under difficult conditions and to the insertion of a
water tight lining.
 (iv) It is suitable for greater depth.
 vi) It can be sunk quicker than a rectangular shaft

8. b) Size of a Shaft :
 The size of the shafts depend on the following factors-
 (i) The purpose of the shaft, whether for raising coal or man, or pumping
water, or ventilation, or stowing. etc. or combination of these.
 ii) The desired output from the mine and the type of winning. By the
deputation of skips it larger output than would be possible with cage
winding for a given shaft section.
 The degree of mechanisation of the mine required.
 The most economical size of a shaft is determined by careful consideration
of all the costs involved, including capital COst of sinking and equipment,
depreciation and interest charges, and running costs for power and
maintenance.

9. Shaft centering
 The precise position of the shaft centre may be fixed by lining out two
cross-lines in line with the winding engine and at right angles thereto,
being their point of intersection being the shaft
 station marks are formed by concrete pillars, 0.6 m square and 1m
deep having iron bolts inserted into each pillar with centres marked as
shown in the figure. The exact centre of the shaft may be found at any
time by cross-stringing from these pillars.
 shaft’s centre and inclination (i.e. verticality in case of a vertical shaft)
are checked from time to time, by the use of a centering device
 The centering apparatus consists of (a) a centre pulley frame running
in a guide rail, (b) a centre pulley, (C) a plumb- wire ieel, and When the
apparatus is in use the accurate positioning of the (d) a rack and
pinion device for sliding the frame into the shaft, centre pulley is
ensured with the stop blocks provided for the purpose.

10. TEMPORARY SUPPORTS IN A SHAFT
 a heavy wooden frame or a frame of steel Frame for
suspending Temporary Supports girder is built across the
shaft top from which the temporary support is suspended.
 Temporary supports to the shaft sides may be done by a
system of steel curbs or skeleton rings which have behind
them a close lining of wooden backing deals or steel
plates. The system of wooden backing deals is shownlin
the figure :
 It consists of mild steel curbs or skeleton rings 100m x
25mm made in segments 3 m long and joined together by
bolted lap joints forming the shape to the circumference
of the shaft.
 The ring may also be of channel section for greater
strength and joined by fish-plates.

11. Permanent Supports :
 A permanent support is necessary for at least one of the following reasons :
 (a) To seal off the country rock from the weathering effects of air and water
and thus preventing the slabb- ing and flaking of the sides.
 (b) To support jointed and broken rocks.
 (c) To resist the static pressure of running ground such sands, alluvium,
gravels, etc.
 (d) To seal off water and to resist its static pressure:
 (e) To prevent any damage or collapse of the shaft section due to bursting of
rocks at great depths.

12. A)Brick walling.
 Brick walling is a common practice for ordinary compact and
moderately wet strata where the stresses are not high. First
class, well burnt bricks (225mm x 115mm x 75mm) are
commonly used. Usual thickness of brick lining may vary
from 0.4m to 0.6m.
 A 150 mm thick la- yer of concrete is then laid down to form
a perfect level bed. A walling curb or crib made of cast iron
or of concrete is then set on the top of the hardened
concrete.

13. The brick walling is built up
from this curb beginning with a
thicker wall at the ledge and
gradually decreasing to the
normal thickeness. To ensure
verticality of the brickwork, side
plumb lines (auxiliary to the
main central plumb line) are
suspended in the shaft.

14. B)Monolithic concrete lining.
 For monolithic concrete lining, concrete in the proportion of 1:2:4 (fresh
cement: sand: coarse aggregate) is suitable for dry shafts. For wet shafts,
richer mixture is preferable.
 To construct monolithic concrete lining, the hard rock from where lining is to
commerce, is dressed and levelled in the same manner as for brick lining to
provide a base. When erecting the lining it is necessary to retain the wet or
plastic concrete in position by a shutterng.
 The first ring of shuttering is carefully centered and levelled
 precautions have to be taken to prevent the water from washing the cement
out of the concrete before it has time to set and this may be done by use of
C.G.I. sheets as back heering.

15. C)Reinforced concrete lining
 Reinforced concrete lining is costly and is used where
high pressures have to be resisted. Concrete lining is
stronger than brick work, offers less frictional resistance
to air current, and can be erected rapidly.
 It is, however, difficult to repair and due to its rigidity
may crack and collapse with slight earth movements.

16. D)Cast Iron Tubbing
 A cast iron lining
known as tubbing is
used as a permanent
watertight lining of
shaft sides in case of
water bearing strata
containing water at
high pressure.

17.  The water bearing strata may have several feeders of water at various
depths and these have to be sealed independent lengths of tubbing, each
made watertight at the top and bottom.
 It is also used as a permanent lining where running sand is encountered
during sinking.
 tubbing is built up of C.I. rings and each such ring consists of a number of
flanged segements, shaped to suit the curvature of the shaft.

18. WALLING PLATFORM,
 Construction of brickwall in a shaft is carried out from a platform
known as walling platform or scaffold of stage or cradle which is
raised about 1.3 metres at a time as the walling rises.
 The central portion of the platform or scaffold consists of two
main runners of sal wood 0.3m square
 Secured in these runners are strong cross-piece leaving a central
opening of 2 m.sq. For kibble to pass through
 The diameter of the platform is made slightly less than that of the
finished shaft.

19.  The platform is suspended by two ropes (preferably locked
Itype) which also serve as guide-ropes for the kibble,
 Four sliding bolts, of 75 mm x 50 mm section and sliding
through strap-iron are used to keep the platform steady
when men are working on it or when it is desired to re-cap
the suspension ropes
 About 1.3 m of walling is built up at a time and the
platform is then raised to its new position
 Raising and lowering of the platform are effected by a
double drum winch or by two winches specially installed at
the surface.

20. Lighting in a Sinking Shaft
 : In addition to electric cap lamps used by individual workers, a
cluster of 4 to 6 bulbs, each 100 watt, 110 volt, electric lamp bulbs,
enclosed in water-tight fitting with reinforced glass, is fixed at the
end of an armoured cable for shaft bottom illumination.

21. Drilling in shaft sinking
 In a conventional method of shaft sinking the drilling operation done by hand held
jack hammer It is operated at the pressure of 6kg force/cm2 by compressed air which
is supply from main compressor install on surface
 Generally , cone or pyramid cut form is used.
 Holes are arranged in a ring form as a thumb rule it may be stated that the number
of hole in a ring is three times of ring diameter Usually 2 or 3 drills work at a time in
shaft
 The hole are 38 mm dia and 1.2 to 1.5 m deep A hole after drilled should be plugged
with wooden plug to prevent blockage of holes by mud

22.  Formula for calculating drilling holes:
 Number of holes=2.54 A+22
where A=Area of shaft in sq metres.
The drilling ratio is a term expressed as
tonnes or cubic metres of rock broken per
metre of drilling. This depends on the
nature of the ground and may range from
about 1 cu. m in soft rocks to 0.8 cu. m or
less in hard rocks.

23. Blasting in shaft sinking
 Explosive is placed in the holes after complete the process of drilling
 Gelatinous high explosive like Ajax G are used in sandstone and shale
 Special Gelatine may be used in very hard rock
 A hole 1.2 to 1.5 m deep, may require 0.6 to 0.9 kg of explosive charge
 Low tension detonators are employed for blasting
 The holes need no stemming as the water in each hole acts as a good stemming material
 Sometimes drill cuttings arc utilized for more cffective stemming
 Blasting of inner ring is to be carricd out first and all the shots in the are connected in series
 Before blasting equipment light ventilation ducts and all equipment are withdraw from shaft to
prevent from damage
 Shots are connected to shot firing cable which is suspended from surface
 Shots are fired from surface by hand operated heavy duty exploder

24. DISPOSAL OF THE DEBRIS. (mucking)
 to permit the rapid emptying of loaded kibbles and afford many methods by
which this may be done
 a general arrange- and safety being essential.
 (i) A set of flat folding door at ground level for men and materials. They may
also be used for handling of debris, if required. The doors, flat when closed,
cover the shaft.
 (ii) A second set of doors, about 10 m above the ground level, used for the
handling of debris. These doors are inverted V-shaped or lie at an angle of
45° with the horizontal like the They include roof of a house, when closed.
 (iii) Steel chute at about 1 in 2 to deliver the debris to the dirt wagon
running on rails at ground level.

25.  The kibble is drawn up clear of the surface-level
doors which are then shut off and the top
doors opened to llow the kibble to pass
through. The top set of doors is then closed
and the kibble lowered on to them and tipped
 The doors are heavy in structure and are
operated by a system of levers either
counterbalanced or worked by compressed air.
Two sets of ladders, one at each side of the
doors, are provided for the banksman and his
assistants to enable them to reach the platform
at V-doors level.

26. Video reguarding drilling, blasting,
mucking process in shaft sinking

27. THE SINKING RIDER
 When a walling platform is used while
sinking is in progress the scaffold ropes are
used as guide ropes for the kibbles above the
point where the walling scaffold is
suspended in the shaft.
 An appliance runs on these ropes supporting
the wall- ing scaffold to guide the kibble and
prevent it from swinging during its ascent
and descent is known as a "rider".
 Rider cone at the centre of rider is so
constructed that the safety hook and capel
are allow to pass through it.

28.  Purposes of the Rider :
The chief purpose of a rider, in con- junction with the ropes supporting the walling platform, is to
steady and guide the kibble when it is above the level of the platform in the shaft.
 Precaution taken when rider employed
1. The central opening in the rider cone must be large enough for the detaching hook to pass
through, so that it may not be prevented from coming into action in the event of an overwind.
2. Any possibility of sticking must be prevented by making the sleeves encircling the guide ropes
long enough and far enough apart to ensure that they guide freely up and down.
3. A number of rubber rings, supported by clamps, must be provided above the cappings
supporting the platform ropes to minimise shock and impact during the descent of the kibble.

29.  1. Pilling method
 2. Caisson method
 3. Freezing methof
 4. Cementation method
Shaft sinking special methods:-

30. Shaft sinking special methods:-
 Pilling System
 This method is known as simply "piling" or
"sheet piling and is suited sinking through
loose deposits of sand, mud, or alluvium near
the surface upto a depth of 20 m.
 Interlocking steel piles, 6 m to 10 m long, are
used and they are practically water-tight
 Additional lengths may be available by welding
or riveting two or three lengths of piles.
 At the surface, the piles are set up to form a
ring and then they are hammered down in
rotation, each member being driven a few
metres at a time by a direct-acting steam piling
hammer.

31. Caisson Methods
i) Sinking drum process or open caisson
method
 This consists of a cylindrical well of brick work, 0.3 m to 0.4 m in thickness over a m.s. ring
having a steel cutting shoe. The shaft is excavated and the drum sinks down gradually by
its own weight.
 As the drum sinks down, further brick work is added on the top.
 A compound sinking drum consisting of brick work surrounded by 13 mm thick steel plates
is sometimes used to resist uncertain tensile stresses. Concrete sinking drums also can be
used.
 Care must be taken to see that the drum descends vertically and with this object
additional weights may be placed over the drum.

32. Ii) Pneumatic caisson method
 This method is adopted when there is a danger of ground filing up the shaft or
where there is considerable inrush of water under a small head. Compressed air
is led into the chamber formed by means of a partition, 1.8 to 2 m above the
cutting shoe compressed air keeps back the water and sand.
 An air lock is mounted on top of the partition as a passage for men material.
The limit of the pressure of the air is 4 kgl/cm beyond which persons cannot work.
This method cannot be used for depths of more than 30 m.
 These caisson methods are commonly adopted for the construction of
foundations for bridges, tall buildings, etc.

33. iii) Forced drop shaft method
 This is commonly adopted where the
strata consists of alternate tough and
loose ground and also when the drop
shaft refuses to sink further due to
very high skin friction.
 In these cases sinking is carried out
with the help of hydraulic rams which
force down the cast iron drums.
 This method can be used for depth
upto 60 m

34. Video reguarding caisson method

35. Freezing Method
 This method is used when the
sinking is proceeding through an
unstable or friable Strata with
heavy inrush of water, or sand
connected with inflow of water
 essentially involves the formation
of a large block of frozen ground
in the water-bearing strata. The
frozen block prevents the influx of
water into the shaft.

36.  The whole process can be divided into three operations.
1 . The first operation consists of drilling holes, usually 150 mm diam. at 2.2 to 3 m
intervals around the shaft from the surface or from a fore shaft.
2. Inside the holes special small tubes are inserted to enable the cold brine (solution of
CaCL2) to be circulated. Cold brine, while circulating in the holes, extracts the heat from
the surrounding strata and the circulation of brine is continued till a wall of ice of
sufficient size is formed. Sinking and lining is carried out in the normal way after the
formation of ice wall.
3. The third and final operation is thawing which consists in removing the ice wall by
sending hot brine through the existing holes.
 This method is very rarely used in India.

37. Cementation process
 This process can be used in all cases of shaft sinking, particularly in any
fissured water- bearing strata except in running sand or loose ground. It can
be successfully applied in sinking even when the inrush of water is heavy.
 Treatment of, ground around the shaft is carried out to achieve one or more
of the following objeetives: (1) To stabilise the collapsing ground, (2) To
reduce the inflow of ground water, (3) To avoid flooding, (4) To prevent sand
“boiling".
 The method consists in drilling the holes as shown in Fig. and then injecting
slurry of water and cement under pressure through the holes till they are
completely sealed of In the past injection was done at low pressures like 6
kgf/cm? but it has been proved that hi pressure of the order of 300 kgf/cm?
can be used successfully. The water cement ratio can e changed according to
the requirements.
 A process known as pre-silicatisation, which reduces the friction of at the rock
to the passage of cement is necessary in certain types of rocks. Extra holes are
drilled forthe purpose and are treated first with silicate of soda and then with
aluminium sulphate.
 The holes to be treated with chemicals are known as "product-hole" and their
number is usually three times that of cementation holes.

38. DEEPENING EXISTING SHAFTS :-
 This is a specia! problem, the method adopted depending on the
precise circumstances in each case.
 (a) If the shaft is disused, it must first be examined, repaired, reventilated and drained.
There- after the necesry sinking cquipment must be installed and the deepening may
proceed in the ordinary manner, tihe debris being wound to the surface.
 (b) It the shaft is used only as an emergency exit, or is to be deepened In a shift not used
for coal-winding the existing pit-bottom may be arranged with folding doors similarly to
an ordinary sinking-pit tep and the debris may be raised to be pit-bottom level by a tail
rope secured to cne of the existing cages. Thereafter, it is disposed of in the existing
workings.

39.  (c) It eoal-winding and déepening have to be carried on
simultaneously, the method shown in fig. 12 nay he adopted.
In this case, a staplt, say 30 ft. deep, is first sunk from the
existing working levei and a heading is driven from the staple
to a point vertically under the winding shaft. This point is
accurately located by a borehole put down from the drained
shaft sump and also by a careful check survey. The slaft is
then driven upwards for a diatance sufhcient to
accommodate the detaching-look plate P and winding
sheaves, but a short Iength of ground G is left intact
 A separate sinking engine is installed at the surface and the
sinking rope is brought down near the side of the shaft,
passing ihrough a borehole and being deflected by a pair of
sheaves to the required centre line. The debris is wound to
the lower landing level L and is thence raised via the staple to
the working level where it may be disposed of in the
workings. On completion of sinking, the ground G is removed
in sections.

40. Widening a shaft
a) If the shaft is disused and not required for men
Or coal winding the procedure is to fill the shaft
to the debris and then to proceed exactly in the
ordinary sinking. The filled in debris forms a safe
platform and is removed with the excavated
material.

41. Widening a shaft which is used for coal
Winding:-
 A totally different technique has to be adopted in which
a strong cylinder steel shield which fits inside the old
shaft in used, which does not interfere with the travel
cages. Sufficient ground at the surface must first be
excavated behind the old shaft working down to a depth
of 30 m. To enable concrete wall to be erected all round
the shaft.
 The next step is to erect a strong platform on girder at a
depth of 4m. Ant to widen the shaft to this depth, the
debris being raised by gab engine and kibble. The
platform is then remove and erected at a depth of 6 shaft
being widen to this depth in a similar way
 The winded shaft should be supported temporarily by
steel ring being hung from the girders at the up and the
platform removed all together.
 All this work is necessary enable the protecting shield
walking platform to be installed in the shaft.

42. references
 Elements of mining technology vol. 1 – D.J. Deshmukh
 Video of drilling – blasting:-
https://youtu.be/FlQYaU98fX8
 Vedo of caission method :-
https://youtu.be/LfVPqihZWO8
 https://youtu.be/Yo4m4PMqeVk

43. Thank you