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Tunneling in soft ground and hard rock

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kamariya keyur
kamariya keyur

The document discusses different methods of tunneling in soft ground and hard rock. It describes various types of soft ground and factors that affect the choice of tunneling method. Methods for soft ground include those using timber supports as well as shield, compressed air, and linear plate methods. For hard rock, common techniques are the full face, heading and bench, and drift methods. Sequence of operations are provided for different soft ground and hard rock tunneling approaches.

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Tunneling in Soft Ground and Hard Rock
Content : - Introduction - Tunneling in soft ground - Tunneling in hard rock - sequence of operation - methods of tunneling
TYPES OF GROUND • HARD GROUND - Self supporting • SOFT GROUND - Running ground - Soft ground - Firm ground - Self supporting ground
TYPES OF SOFT GROUND • Running ground : required support immediately ,e.g. dry sand • Soft ground : roof requires immediate support while sides can remain standing for few minutes. • Firm ground : roof can stand for few minutes and sides for much longer time ; e.g. dry earth • Self supporting ground : remain unsupported up to short length of 1.5 to 4 m. ; e.g. sand stone
 FACTOR AFFECTING THE CHOICE OF A METHOD • Size of tunnel • Type of ground • Available equipment • Method of sequence of excavation • The extent of ground support method • The method of attacking the heading
• METHOD OF TUNNELLING IN SOFT GROUND METHODES REQUIRING USE OF TIMBERS • Fore poling method • Needle beam method • Army method • Belgian method • English method • American method • Austrian method • German method • Italian method OTHER METHOD • Linear plate method • Shield method • Compressed air method
FORE POLING METHOD
• Used for running ground • Now replace by compressed air tunneling  Sequence of operations for 1.50x1.50 mtr. • Sunking of shaft • Bent is placed from the sheeting • Holes are driven in the sheeting from 7.5 c/c above the cap and below the cap. • Fore pole consist of plank with wedge ends are entered one at a time • Driven through half length at 15 cm/mtr inclination
• Timber laid at the end of all spiles. • Face sheeting broken out and ground is allowed to run. • Put temporary supports at end called horse head. • The other end of forepole is supported with board of size 45 cm. • Now, repeat the procedure and inserted boom for the support of board. merits : • Used without compressed air • Used for small dimensions in running ground demerits : • slow process • used only for small cross section
Tunneling in soft ground and hard rock
NEEDLE BEAM
• It consist of a stout timber beam from main temporary support • It is used when the soil roof can stand for a few minutes Sequence of operation : • A drift of about 1 mts. is driven on working face • Roof of this drift is lagged with sheeting • Apply trench jack on it • A needle beam of 5 to 6 mtr. is inserted and one end is carried on plank and other on stout post. • With help of jacks , drift is widened side ways
BELGIAN METHOD It is used for moderately firm or hard soils.
SEQUENCE OF OPERATION : • A top heading ABCD for the full rise of the arch is driven & supported. • Heading is widened sideways , and supported by additional crown bars on sill. • Oiling the arch • Inserted the shore at side and excavate the MNOP. • Shoring is removed and space is filled with masonary.
Tunneling in soft ground and hard rock
ARMY METHOD OR CASE METHOD • It is derived by USA army for constructing small tunnels at shallow depth
SEQUENCE OF OPERATION : • A common gallery of wood 1.1x1.8x0.05 mtr. of wood is used. • A top braced is removed and ground is excavated for a short distance. • The box is moved ahead and set next cap. • After that remove the breast one by one and excavate . MERITS : • Simple,economic • Outskilled labour can driven DEMERITS : • Only for short tunnel
ENGLISH METHOD • The main characteristic of this method is excavation of full section of the tunnel at once using longitudinal struting and alternate of masonary work and excavation.
Tunneling in soft ground and hard rock
SEQUENCE OF OPERATION : • Top head is driven upto 5 mtr. • It is supported on crown bars • Then widening of the heading is then done by digging away the earth at each side. • Then started excavation of part -2 and put the sill • Part -3 in same manor and started masonary
MERITES : • simple method of hauling are possible • masonary lining is built , so making the construction strong and homogeneous. DEMERITES : • use of lots of timber • process are slower due to alternate of excavation & masonary
AMERICAN METHOD • It is used for railway or highway tunneling
SEQUENCE OF OPERATION : • a top drift is driven and supported by laggings,cap timber and parts • side are widened • walls plates are introduced at the springing supporting the arch set • vertical posts are driven • sides and benching are cleared & tunnel lining is started
LINIER PLATE METHOD • It is presented steel plates ,plain or corrugated are used to support the soil during excavation. • The size of plates are 0.9 x 0.4 with flange of .05 mtr. • The plates are bolted to each other through holes in flange.
Tunneling in soft ground and hard rock
SEQUENCE OF OPERATION : • A hole of 0.4 mt. depth is cut at crown and liner plate “ a” is inserted • Excavated sides and place “b” and “c” plates • Now two wooden wall plates of size about 20 cm. x 5 cm. and placed on each side of the bench • Jacks are removed • The bench is then cleared and the wall plates are under pinned at bottom
Tunneling in soft ground and hard rock
SHEILD METHOD • It is used for driving a tunnel through water bearing strata. • It is an equipment which acts as a bridge with roof for workers. • It open at one end or both end. • It consist sledges , conveyors etc. LENGTH OF SHEILD : 1.storage required 2.problemes of changing direction
SHAPE OF SHIELD : • Resistance of motion : contact area of the shape • Cross section area / unit perimeter for circular and square=d/4 • Resistance to pressure caused by surrounding soil : circular is best • Permission for rotation of shield about its own axis : circular is preferable
Tunneling in soft ground and hard rock
SEQUENCE OF OPERATION : • The ground is excavated ahead of the sheild of .45 to .75 meter. • The shield is jacked forward. PRIMARY LINING : • It is the name given to the heavy cast iron lining used in conjuction with the shield. • SECONDARY LINING : • 5 to 7 cm. concrete is placed over the flange of iron.
COMPRESSED AIR METHOD • Used of compressed air • Used in soft ground COMPRESSED AIR TUNNELING IN CLAY : • No timbering is required inside the tunnel • Pressure required inside the tunnel is p = wh. ;w=weight of soil
Tunneling in soft ground and hard rock
EQUIPMENTES FOR COMPRESSED AIR TUNNELING : • air lock & accessories • bulk head to fix air lock • blow line • air compressor • gas trapes • DURATION OF WORK IN COMPRESSED AIR FOR LABOURES : • p = 12.5 pa ;8 hr(break 0.5 hr) • p= 14 to 21 pa; 4 hr (break 2hr)
Tunneling in soft ground and hard rock
Tunneling in Hard Rock
• Sequence of operation : 1. Locating centre line on the ground. 2. Construction of shaft. 3. Transferring centre line to the inside of tunnel. 4. Setting up and drilling hole for blasting. 5. Loading holes and carrying out blasting 6. Providing ventilation. 7. Loading and hauling muck. 8. Pumping of ground water. 9. Electric supports 10. Placing reinforcement steel. 11. Placing concrete lining.
Methods of tunneling in rock 1. Full face method 2. Heading and bench method 3. Drift method
Full face method
• In this whole section of tunnel is attacked at the same time.It is suitable for the small cross sectional area about 3 m dia. • Entire section is drilled, the holes are charged and explosives are discharged • Bars are installed whose width is less than height. • Columns are installed vertically whose height is less than its width.
Heading and Bench method
• It is used when tunnel is very large and the quality of rock is not satisfactory. • If rock is hard and self supporting heading advanced ahead by one round ahead of the bench. • The bench provides platform for timber supports. • To heading is usually 3 to 3.5 m ahead of bench.
Drift method • A drift is a small tunnel driven through all or a portion of the length of the tunnel prior to excavating full bore. • Types: 1. Centre drift 2. Side drift 3. Top drift 4. Bottom drift
Centre drift
• Generally 3 * 3 m to 2.5 * 2.5 m centre drift is driven through portal to portal. • Holes for enlargement are ring drilled with a drill set upon the axis of tunnel. ADVANTAGES : • Good ventilation • Mucking work does not disturbed • Elaborate supporting system not required.
Side drift - Two drifts are advanced along the sides of tunnel. - Breakups are then made in form of arch and permanent timbering is erected to support the roof.
Top drift • When a drift section chosen lies in top of the tunnel section it called top drift.
Bottom drift • In this , the lower part is first blasted and cleared for the full length.
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Tunneling in soft ground and hard rock

  • 1. Tunneling in Soft Ground and Hard Rock
  • 2. Content : - Introduction - Tunneling in soft ground - Tunneling in hard rock - sequence of operation - methods of tunneling
  • 3. TYPES OF GROUND • HARD GROUND - Self supporting • SOFT GROUND - Running ground - Soft ground - Firm ground - Self supporting ground
  • 4. TYPES OF SOFT GROUND • Running ground : required support immediately ,e.g. dry sand • Soft ground : roof requires immediate support while sides can remain standing for few minutes. • Firm ground : roof can stand for few minutes and sides for much longer time ; e.g. dry earth • Self supporting ground : remain unsupported up to short length of 1.5 to 4 m. ; e.g. sand stone
  • 5.  FACTOR AFFECTING THE CHOICE OF A METHOD • Size of tunnel • Type of ground • Available equipment • Method of sequence of excavation • The extent of ground support method • The method of attacking the heading
  • 6. • METHOD OF TUNNELLING IN SOFT GROUND METHODES REQUIRING USE OF TIMBERS • Fore poling method • Needle beam method • Army method • Belgian method • English method • American method • Austrian method • German method • Italian method OTHER METHOD • Linear plate method • Shield method • Compressed air method
  • 8. • Used for running ground • Now replace by compressed air tunneling  Sequence of operations for 1.50x1.50 mtr. • Sunking of shaft • Bent is placed from the sheeting • Holes are driven in the sheeting from 7.5 c/c above the cap and below the cap. • Fore pole consist of plank with wedge ends are entered one at a time • Driven through half length at 15 cm/mtr inclination
  • 9. • Timber laid at the end of all spiles. • Face sheeting broken out and ground is allowed to run. • Put temporary supports at end called horse head. • The other end of forepole is supported with board of size 45 cm. • Now, repeat the procedure and inserted boom for the support of board. merits : • Used without compressed air • Used for small dimensions in running ground demerits : • slow process • used only for small cross section
  • 12. • It consist of a stout timber beam from main temporary support • It is used when the soil roof can stand for a few minutes Sequence of operation : • A drift of about 1 mts. is driven on working face • Roof of this drift is lagged with sheeting • Apply trench jack on it • A needle beam of 5 to 6 mtr. is inserted and one end is carried on plank and other on stout post. • With help of jacks , drift is widened side ways
  • 13. BELGIAN METHOD It is used for moderately firm or hard soils.
  • 14. SEQUENCE OF OPERATION : • A top heading ABCD for the full rise of the arch is driven & supported. • Heading is widened sideways , and supported by additional crown bars on sill. • Oiling the arch • Inserted the shore at side and excavate the MNOP. • Shoring is removed and space is filled with masonary.
  • 16. ARMY METHOD OR CASE METHOD • It is derived by USA army for constructing small tunnels at shallow depth
  • 17. SEQUENCE OF OPERATION : • A common gallery of wood 1.1x1.8x0.05 mtr. of wood is used. • A top braced is removed and ground is excavated for a short distance. • The box is moved ahead and set next cap. • After that remove the breast one by one and excavate . MERITS : • Simple,economic • Outskilled labour can driven DEMERITS : • Only for short tunnel
  • 18. ENGLISH METHOD • The main characteristic of this method is excavation of full section of the tunnel at once using longitudinal struting and alternate of masonary work and excavation.
  • 20. SEQUENCE OF OPERATION : • Top head is driven upto 5 mtr. • It is supported on crown bars • Then widening of the heading is then done by digging away the earth at each side. • Then started excavation of part -2 and put the sill • Part -3 in same manor and started masonary
  • 21. MERITES : • simple method of hauling are possible • masonary lining is built , so making the construction strong and homogeneous. DEMERITES : • use of lots of timber • process are slower due to alternate of excavation & masonary
  • 22. AMERICAN METHOD • It is used for railway or highway tunneling
  • 23. SEQUENCE OF OPERATION : • a top drift is driven and supported by laggings,cap timber and parts • side are widened • walls plates are introduced at the springing supporting the arch set • vertical posts are driven • sides and benching are cleared & tunnel lining is started
  • 24. LINIER PLATE METHOD • It is presented steel plates ,plain or corrugated are used to support the soil during excavation. • The size of plates are 0.9 x 0.4 with flange of .05 mtr. • The plates are bolted to each other through holes in flange.
  • 26. SEQUENCE OF OPERATION : • A hole of 0.4 mt. depth is cut at crown and liner plate “ a” is inserted • Excavated sides and place “b” and “c” plates • Now two wooden wall plates of size about 20 cm. x 5 cm. and placed on each side of the bench • Jacks are removed • The bench is then cleared and the wall plates are under pinned at bottom
  • 28. SHEILD METHOD • It is used for driving a tunnel through water bearing strata. • It is an equipment which acts as a bridge with roof for workers. • It open at one end or both end. • It consist sledges , conveyors etc. LENGTH OF SHEILD : 1.storage required 2.problemes of changing direction
  • 29. SHAPE OF SHIELD : • Resistance of motion : contact area of the shape • Cross section area / unit perimeter for circular and square=d/4 • Resistance to pressure caused by surrounding soil : circular is best • Permission for rotation of shield about its own axis : circular is preferable
  • 31. SEQUENCE OF OPERATION : • The ground is excavated ahead of the sheild of .45 to .75 meter. • The shield is jacked forward. PRIMARY LINING : • It is the name given to the heavy cast iron lining used in conjuction with the shield. • SECONDARY LINING : • 5 to 7 cm. concrete is placed over the flange of iron.
  • 32. COMPRESSED AIR METHOD • Used of compressed air • Used in soft ground COMPRESSED AIR TUNNELING IN CLAY : • No timbering is required inside the tunnel • Pressure required inside the tunnel is p = wh. ;w=weight of soil
  • 34. EQUIPMENTES FOR COMPRESSED AIR TUNNELING : • air lock & accessories • bulk head to fix air lock • blow line • air compressor • gas trapes • DURATION OF WORK IN COMPRESSED AIR FOR LABOURES : • p = 12.5 pa ;8 hr(break 0.5 hr) • p= 14 to 21 pa; 4 hr (break 2hr)
  • 37. • Sequence of operation : 1. Locating centre line on the ground. 2. Construction of shaft. 3. Transferring centre line to the inside of tunnel. 4. Setting up and drilling hole for blasting. 5. Loading holes and carrying out blasting 6. Providing ventilation. 7. Loading and hauling muck. 8. Pumping of ground water. 9. Electric supports 10. Placing reinforcement steel. 11. Placing concrete lining.
  • 38. Methods of tunneling in rock 1. Full face method 2. Heading and bench method 3. Drift method
  • 40. • In this whole section of tunnel is attacked at the same time.It is suitable for the small cross sectional area about 3 m dia. • Entire section is drilled, the holes are charged and explosives are discharged • Bars are installed whose width is less than height. • Columns are installed vertically whose height is less than its width.
  • 42. • It is used when tunnel is very large and the quality of rock is not satisfactory. • If rock is hard and self supporting heading advanced ahead by one round ahead of the bench. • The bench provides platform for timber supports. • To heading is usually 3 to 3.5 m ahead of bench.
  • 43. Drift method • A drift is a small tunnel driven through all or a portion of the length of the tunnel prior to excavating full bore. • Types: 1. Centre drift 2. Side drift 3. Top drift 4. Bottom drift
  • 45. • Generally 3 * 3 m to 2.5 * 2.5 m centre drift is driven through portal to portal. • Holes for enlargement are ring drilled with a drill set upon the axis of tunnel. ADVANTAGES : • Good ventilation • Mucking work does not disturbed • Elaborate supporting system not required.
  • 46. Side drift - Two drifts are advanced along the sides of tunnel. - Breakups are then made in form of arch and permanent timbering is erected to support the roof.
  • 47. Top drift • When a drift section chosen lies in top of the tunnel section it called top drift.
  • 48. Bottom drift • In this , the lower part is first blasted and cleared for the full length.