TUNNELING IN ROCK MASS:(NECESSITY, SYSTEMATIC APPROACH, PLANNING AND CONSTRUCTION)

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APPLIED MECHANICS DEPARTMENTSVNIT,SURAT

GUIDED BY : SUBMITTED BY:PROF S.KUMAR JOSHI AKSHAY p16SM006

TUNNEL: A TUNNEL IS AN UNDERGROUND OR UNDERWATER PASSAGE WAY, DUG THROUGH THE SURROUNDING SOIL/EARTH/ROCK AND ENCLOSED EXCEPT FOR ENTRANCE AND EXIT,

TYPE BASED ON APPLICATION

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VEHICULAR TUNNEL

RAIL TUNNEL

CANAL TUNNEL

NECESSITY

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To minimize land acquisition costsTo minimize land acquisition costs

To avoid steep grades and longer To avoid steep grades and longer routes.routes.

To avoid impact on environmentally sensitive areas.

To avoid impact on cultural heritage

SYSTEMATIC APPROACH & PLANNING

STAGES OF PLANNING

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PRE-PLANNING

DETAIL PLANNING

MONITARING AND CONTROL

PRE-PLANNING

Justification for taking up the project Objectives of the project Alignment Selection Investigation Examining alternatives Cost benefit analysis Financial planning

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ALIGNMENTALIGNMENT SELECTIONSELECTION

The Alignment of the Tunnel must be consistent with the alignment of the roadway leading to it.

The Alignment must consider factors like the sight distances, minimum turning radius and design speeds in its design.

Except for maintenance reasons, two way roads should be discouraged in a single tube of tunnel, for safety reasons.

Pedestrian and Cyclist use of tunnels should be discouraged except a special passage is designed for them.

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INVESTIGATIONSINVESTIGATIONS

Several investigations are required at the preliminary, design and construction phases of a tunnel project. The processes are highlighted below: Collection and Review of Available Information for a general knowledge of the area (Existing Topographical, hydrological, Geological, Geotechnical, Seismic, Environmental, Zoning etc) Topographic and Aerial PhotographsPreliminary Surveys Water Well Logs Hydrographic Surveys

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Identification of Underground Structures and Obstacles

Geologic Mapping Subsurface Investigations Test Borings and Sampling Soil and Rock Identification and Classification In - situ Tests •Geophysical Tests •Seismic Wave

Propagation •Laboratory Tests •Groundwater Investigation •Pumping Tests

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COSTRUCTION

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11 . . TUNNEL CONSTRUCTION SYSTEMSTUNNEL CONSTRUCTION SYSTEMS

(a)(a) Cut and Cover System.Cut and Cover System.

(b)(b) Pipe Jacking System (Micro Tunneling).Pipe Jacking System (Micro Tunneling).

(c)(c) Shield Tunneling (TBM).Shield Tunneling (TBM).

(d)(d) New Austrian Tunneling Method New Austrian Tunneling Method (NATM).(NATM).

(e)(e) Immersed-Tube Tunneling System.Immersed-Tube Tunneling System.

Tunnel Construction

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(a) Cut and Cover System(a) Cut and Cover System

Sequence of Construction (Stages 1 to 3Sequence of Construction (Stages 1 to 3 ))

Tunnel Construction

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(a) Cut and Cover System(a) Cut and Cover System

Sequence of Construction (Stages 4 to 6)Sequence of Construction (Stages 4 to 6)

Tunnel Construction

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Cut and Cover SystemCut and Cover System

AdvantagesAdvantages ::• Economy for shallow depths (4 - 10 m) and for

shorter applications.

• Un-sophisticated labor and equipment required.

• Adaptability to different conditions.

• Simple structural & geotechnical analyses required.

• Safe environment (ventilation and fire hazard)

• DisadvantagesDisadvantages ::• Possible disturbances to existing facilities.• Practical limitations of depth.• Unsuitability under buildings or water.

Tunnel Construction

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Soil Grouting TechniquesSoil Grouting Techniques

Jet Grouting: Soil Replacement ProcessJet Grouting: Soil Replacement Process

Tunnel Construction

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Soil Grouting TechniquesSoil Grouting Techniques

Slurry Wall ConceptSlurry Wall Concept

Tunnel Construction

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(( bb ) Pipe Jacking System (Micro Tunneling)) Pipe Jacking System (Micro Tunneling)

Schematic RepresentationSchematic Representation

Tunnel Construction

STAGES OF BORING

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GUIDANCE AND POSITIONING USINGLASER-GUIDED STEERING SYSTEM

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Laser Guide &Laser Guide &Control Control MonitorMonitor

Screen CaptureScreen Capture

Tunnel Construction

MTBM - SHIELDS OF DIFFERENT SIZES

DIA. RANGES FROM 0.5M TO 3M

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Tunnel Construction

MTBM - DIFFERENT SHAPES OF CUTTING HEADS

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Dirt cutter headDirt cutter head(clay and silty (clay and silty

sand)sand)

Sand shelves Sand shelves

Carbide cutter headCarbide cutter head(soft to medium hard (soft to medium hard

rockrock) )

Tunnel Construction

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Pipe Jacking System (Micro Tunneling)Pipe Jacking System (Micro Tunneling)AdvantagesAdvantages ::

• Suitability for almost all types of soil.

• Large depths with unlimited lengths of drive.

• High levels of accuracy and safety.

• Wide choice of pipe and joint materials.

• High construction rates.

• Reduced manpower requirements.

• Reduced environmental disturbance.

• DisadvantagesDisadvantages ::• Sophisticated equipment and highly skilled

labor.• Inability to make rapid changes in line or level.• Very expensive corrective actions, if required

Tunnel Construction

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(c) Shield Tunneling (TBM) (c) Shield Tunneling (TBM)

Cutter Head Tunnel Tube

Tunnel Construction

CONSTRUCTION SEQUENCE

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Tunnel Construction

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Shield Tunneling (TBM)Shield Tunneling (TBM)

AdvantagesAdvantages ::

• Suitability for almost all types of soil.

• Suitability for wide tunnels (highway, railway, etc.).

• Large depths ( > 10 m), with unlimited lengths of drive.

• Reducing environmental disturbance and utilities diversions.

Tunnel Construction

DisadvantagesDisadvantages ::

• Sophisticated equipment and highly skilled labor.

• Inability to make rapid changes in line or level.

• Very expensive corrective actions, if required.

• Difficult structural and geotechnical analyses reqd..

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(d) (d) New Austrian Tunneling Method (New Austrian Tunneling Method (NATM)NATM)Tunnel Construction

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NATMNATMAdvantagesAdvantages ::

• Best alternative for non-circular roadway tunnels.

• Suitability for almost all stable to strong ground types, including rock.

• Suitability for a variety of soil conditions.

• Small thickness of tunnel lining, reducing the amount of excavation.

• Economy and speed of construction.

Tunnel Construction

DisadvantagesDisadvantages ::

• Highly skilled workers and expert engineers.

• Safety measures for shotcrete application.

• Ground water freezing and/or soil strengthening (in case of water-bearing cohesionless soil).

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(e) Immersed-Tube Tunneling System(e) Immersed-Tube Tunneling SystemTunnel Construction

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(E) Immersed-Tube Tunneling System(E) Immersed-Tube Tunneling System

Construction SequenceConstruction Sequence ::

1. Dredging the trench in river or sea bottom.2. Prefabrication of tunnel sections, and sealing

ends with bulkheads.3. Floating the sections to the tunnel trench.4. Lowering the sections to seabed.5. Joining the sections together underwater.6. Removing the temporary bulkheads.7. Backfilling the trench.

Tunnel Construction

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Immersed-Tube Tunneling SystemImmersed-Tube Tunneling System

AdvantagesAdvantages ::

• Economy (most economical alternative for any type of underwater tunnel crossing).

• High construction rates (particularly for steel tube tunnels).

• Wide variety of different conditions.

DisadvantagesDisadvantages ::• Highly skilled and experienced workers.

• Safety measures for underwater construction..

Tunnel Construction

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DEVELOPMENTS & FUTURE TRENDSDEVELOPMENTS & FUTURE TRENDSIN TUNNEL CONSTRUCTIONIN TUNNEL CONSTRUCTION

Conventional TunnelingConventional Tunneling ::

Areas Developments

Blast Tunneling • Drilling techniques. • Blasting technology. • Re-use of excavated material.

Tunneling in Loose

Sand

• Injection. • High-pressure injection. • Soil freezing.

Shotcrete Safety Measures

• Special shotcretes without accelerators that reduce concrete solidity.

General Equipment Developments

• Advances in diesel motor technology (less pollutants in exhausted gases).

Handling of Groundwater

• Two-layer plastic sealing tracks (double water-pressure resistance).

Final Lining in Concrete

• Measures for protecting inner concrete linings (to prevent tears).

Tunnel Construction

REFERANCES

http://terratec.co/files/TERRATEC-Microtunnelling-Brochure.pdf http://www.railsystem.net/natm/ http://www.dr-sauer.com/technical-info/906 https://en.wikipedia.org/wiki/Tunnel

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Thank you Thank you

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Tunnel Construction