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Tunnelling methods

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Durgesh Kumar Yadav
Durgesh Kumar Yadav

This document discusses various methods of tunneling in soft soil, including timbering methods like the fore-poling method and needle beam method, as well as other methods like the shield method and compressed air method. It provides details on the sequence of operations and characteristics of different tunneling methods based on the type of soft soil present, including challenges around maintaining air pressure for compressed air tunneling.

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Submitted by: •Durgesh Kumar Yadav
 Soil classification  Soft soil classification  Challenges in tunneling  Methods of tunneling in soft soil
 Methods adopted for tunneling may vary with soil present in the construction site.  Soil present on site can be classified as : 1. Soft soil , which requires temporary support during and after excavation. 2. Hard rocks or Fully self supporting soil
Soft soil Running Ground Soft Ground Firm Ground Self supporting ground •Needs instant support during excavation. •Dry sand, gravel ,silt etc. •Roof needs instant support after excavation. •Walls can withstand for few minutes only without support •Soft earth, clay, damp sand. •Roof can withstand without support for few minutes. •Walls can stand for 1 or 2 hours after excavation. •Dry earth, firm clay, cemented sand etc. •Ground can stand unsupported while excavation is done for 1.5m to 5m. •Sand stones, hard clay etc.
 Preventing soil movement.  Soil pressure.  Water seepage
1. Which requires timbering. 2. Other methods.  Which requires timbering : i. Fore-poling method ii. Needle beam method iii. Belgian method iv. Austrian method v. American method vi. English method vii. Army method or Case method viii. German method ix. Italian method
• Ancient method, used for running ground • Now replace by compressed air tunneling method • Slow, tedious method but safe. • Skilled labours and strict provision required. Sequence of operations for 1.52x1.52 m. • “A” frame prepared and placed near facing of tunnel. • Poles are inserted at top which are supported by vertical posts.  Bent is placed from the sheeting  Now the excavation can be done under forepoles  Fore pole consist of plank with wedge ends are entered one at a time  Driven through half length at 15 cm/m inclination
Tunnelling methods
• Suitable for firm ground • Needle beam consist of a stout timber beam from main temporary support  SEQENCE OF OPERATION :  a drift of about 1m. is driven on working face  roof of this drift is lagged with sheeting  apply trench jack on it  a needle beam of 5 to 6m. is inserted and one end is carried on plank and other on stout post.  with help of jacks , drift is widened side ways
Tunnelling methods
MERITS :  economical  works all right on brick lining DEMERITS :  heavy beam pushed foreward by hand  no. of trench jacks required  difficulties in concrete lining with machine
 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. • Lining the arch • Inserted the shore at side and excavate the mnop. • Shoring is removed and space is filled with masonary.
Tunnelling methods
Tunnelling methods
 It is also known as “sequential excavation method”.  A center cut is taken for full height .  Cut is widened to full face.  Permit short section of masonry to be completed.
Tunnelling methods
• 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 clared & tunnel lining is started
Tunnelling methods
• The main characteristic of this method is excavation of full section of the tunnel at once using longitudinal strutting and alternate of masonry work and excavation SEQUENCE OF OPERATION :  Top head is driven up to 5 m.  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 masonry
Tunnelling methods
• 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 .
Tunnelling methods
MERITS :  Simple,economic  Unskilled labour can driven DEMERITS :  Only for short tunnel
• In this method 3 drifts are used to support the roof and side . • One at the crown and rest two are at bottom along the wall.
 Other methods : i. Linear plate method ii. Shield method iii. Compressed air method
• It is presented steel plates ,plain or corrugated are used to support the soil during excavation. • The size of plates are 0.91 x 0.41m with flange of .05 m. • The plates are bolted to each other through holes in flange. SEQUENCE OF OPERATION :  a hole of 0.4 m 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.
Tunnelling methods
 LINEAR PLATE WITH STIFFNERES : • For strenthen the plate “I” or “T” section rib is used as stiffners. MERITES :  Lighter, economical  Erected with unskilled labour  Fire proof  Require less number of joints
• It is used for driving a tunnel through water bearing strata. • It is an equipment which acts as a bridge with roof for workers. • A shield is a movable frame and it is used to support the face of the tunnel. • The excavation & lining of tunnel can be carried out under protection of shield.
Tunnelling methods
COMPONENTES OF SHIELD : 1.The skin 2.Cutting edge 3.Propelling jack 4.The hood 5.The tail 6. Port holes
SEQUENCE OF OPERATION : •The ground is excavated ahead of the shield 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 conjunction with the shield. SECONDARY LINING : •5 to 7 cm. Concrete is placed over the flange of iron. MERITS : •Full dimension available •Speedy •Moving with constant support to the advanced tunnel.
Tunnelling methods
• Most modern method used for tunneling in soft grounds having water bearing strata. • Timber support is not required. • Support is provided by compressed air into enclosed space to prevent the collapse of roof and sides of tunnel. • Usually air is used in conjunction with a shield and air-tight locks. • Air pressure adopted is approximately 1kg/cm^2.
• If pressure will be more than working hour will reduce which will increase the cost of labours and the construction cost as well.  Challenges occurs in maintaining air pressure : I. Earth pressure varies from top to bottom in a tunnel. II. Pressure in floor depends upon the nature of soil strata. III. Value of pressure varies with moisture content of soil strata. IV. Compressed air will escape continuously through the pores of soil , thus air pressure will have vary time to time to get balanced.
Tunnelling methods
Tunnelling methods
Tunnelling methods
Tunnelling methods

More Related Content

Tunnelling methods

  • 2.  Soil classification  Soft soil classification  Challenges in tunneling  Methods of tunneling in soft soil
  • 3.  Methods adopted for tunneling may vary with soil present in the construction site.  Soil present on site can be classified as : 1. Soft soil , which requires temporary support during and after excavation. 2. Hard rocks or Fully self supporting soil
  • 4. Soft soil Running Ground Soft Ground Firm Ground Self supporting ground •Needs instant support during excavation. •Dry sand, gravel ,silt etc. •Roof needs instant support after excavation. •Walls can withstand for few minutes only without support •Soft earth, clay, damp sand. •Roof can withstand without support for few minutes. •Walls can stand for 1 or 2 hours after excavation. •Dry earth, firm clay, cemented sand etc. •Ground can stand unsupported while excavation is done for 1.5m to 5m. •Sand stones, hard clay etc.
  • 5.  Preventing soil movement.  Soil pressure.  Water seepage
  • 6. 1. Which requires timbering. 2. Other methods.  Which requires timbering : i. Fore-poling method ii. Needle beam method iii. Belgian method iv. Austrian method v. American method vi. English method vii. Army method or Case method viii. German method ix. Italian method
  • 7. • Ancient method, used for running ground • Now replace by compressed air tunneling method • Slow, tedious method but safe. • Skilled labours and strict provision required. Sequence of operations for 1.52x1.52 m. • “A” frame prepared and placed near facing of tunnel. • Poles are inserted at top which are supported by vertical posts.  Bent is placed from the sheeting  Now the excavation can be done under forepoles  Fore pole consist of plank with wedge ends are entered one at a time  Driven through half length at 15 cm/m inclination
  • 9. • Suitable for firm ground • Needle beam consist of a stout timber beam from main temporary support  SEQENCE OF OPERATION :  a drift of about 1m. is driven on working face  roof of this drift is lagged with sheeting  apply trench jack on it  a needle beam of 5 to 6m. is inserted and one end is carried on plank and other on stout post.  with help of jacks , drift is widened side ways
  • 11. MERITS :  economical  works all right on brick lining DEMERITS :  heavy beam pushed foreward by hand  no. of trench jacks required  difficulties in concrete lining with machine
  • 12.  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. • Lining the arch • Inserted the shore at side and excavate the mnop. • Shoring is removed and space is filled with masonary.
  • 15.  It is also known as “sequential excavation method”.  A center cut is taken for full height .  Cut is widened to full face.  Permit short section of masonry to be completed.
  • 17. • 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 clared & tunnel lining is started
  • 19. • The main characteristic of this method is excavation of full section of the tunnel at once using longitudinal strutting and alternate of masonry work and excavation SEQUENCE OF OPERATION :  Top head is driven up to 5 m.  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 masonry
  • 21. • 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 .
  • 23. MERITS :  Simple,economic  Unskilled labour can driven DEMERITS :  Only for short tunnel
  • 24. • In this method 3 drifts are used to support the roof and side . • One at the crown and rest two are at bottom along the wall.
  • 25.  Other methods : i. Linear plate method ii. Shield method iii. Compressed air method
  • 26. • It is presented steel plates ,plain or corrugated are used to support the soil during excavation. • The size of plates are 0.91 x 0.41m with flange of .05 m. • The plates are bolted to each other through holes in flange. SEQUENCE OF OPERATION :  a hole of 0.4 m depth is cut at crown and liner plate “ a” is inserted.
  • 27. 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.
  • 29.  LINEAR PLATE WITH STIFFNERES : • For strenthen the plate “I” or “T” section rib is used as stiffners. MERITES :  Lighter, economical  Erected with unskilled labour  Fire proof  Require less number of joints
  • 30. • It is used for driving a tunnel through water bearing strata. • It is an equipment which acts as a bridge with roof for workers. • A shield is a movable frame and it is used to support the face of the tunnel. • The excavation & lining of tunnel can be carried out under protection of shield.
  • 32. COMPONENTES OF SHIELD : 1.The skin 2.Cutting edge 3.Propelling jack 4.The hood 5.The tail 6. Port holes
  • 33. SEQUENCE OF OPERATION : •The ground is excavated ahead of the shield 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 conjunction with the shield. SECONDARY LINING : •5 to 7 cm. Concrete is placed over the flange of iron. MERITS : •Full dimension available •Speedy •Moving with constant support to the advanced tunnel.
  • 35. • Most modern method used for tunneling in soft grounds having water bearing strata. • Timber support is not required. • Support is provided by compressed air into enclosed space to prevent the collapse of roof and sides of tunnel. • Usually air is used in conjunction with a shield and air-tight locks. • Air pressure adopted is approximately 1kg/cm^2.
  • 36. • If pressure will be more than working hour will reduce which will increase the cost of labours and the construction cost as well.  Challenges occurs in maintaining air pressure : I. Earth pressure varies from top to bottom in a tunnel. II. Pressure in floor depends upon the nature of soil strata. III. Value of pressure varies with moisture content of soil strata. IV. Compressed air will escape continuously through the pores of soil , thus air pressure will have vary time to time to get balanced.