Tunnel Boring Machine

Engineering & Technology

Updates-Presentation

The Tunnel Boring Machine

Presented By: Siddhartha Kamat-251075

Gourav Kapoor-251076 Rohit Kaushik-2510

Kabir Mansharamani-251104

Contents of the Presentation

• Introduction

• Types of Tunnel Boring Machine

• Requirements of a TBM

• Opportunities in India

• Procurement

• Parts and Operation of a TBM-Video

• TBM Utilization

• Suitability of a TBM

• Performance of a TBM

• Advantages

• Risks Involved

• Comparison between TBM and DBM

Introduction

• Excavation of Tunnels-Also known as the “mole”-Hard rock or Sand

• Tunnel Diameters range from 1m to 19.25m to date

• TBM as an alternative to the DBM

• Advantages over DBM

• Major Disadvantage-Upfront Cost-Expensive to Construct and Transport

• Tunnelling with TBM is more efficient as tunnel lengths increase

• The first boring machine-in 1845-Commisioned to link France and Italy

through the Alps

• 2 major Classifications of TBM-Hard Ground and Soft Ground TBM’s

Types of TBM’s-Slurry Type

In soft ground-very high water pressure-large amount of G/W-completely enclosed work environment-bentonite slurry mixed with soil-slurry transported via tubes outside for separation-recycled back.

Types of TBM’s-Soft Ground EPB

In soft ground-less than 7 bar pressure-cutter head uses discs as well as combination of tungsten carbide cutting bits, carbide disc cutters and hard rock disc cutters-capable of holding soft ground by maintaining balance b/w earth and pressure.

Types of TBM’s-Hard Ground

Uses disc cutters mounted in cutter head-create compressive stress fractures in the rock-causing it to chip away from the rock into tunnel face-belt conveyor removes the muck-gripper system to advance.

Requirements of a TBM

• High Financial Capabilities of the Client

• High Upfront Payment Capabilities

• Supporting Infrastructure for Launching, Operation and Maintenance

• High Mechanical Background Support Staff

• Good Logistic Capabilities

• Suitability to Terrain and Geological Conditions

• Highly Skilled Personnel

• Technical and Financial Feasibility

Opportunities in India

• Hydro Tunnels-NHPC, NTPC, TDHC, NEEPCO

• Transport Tunnels-NHAI, Delhi Metro, Kolkata Metro, Mumbai Metro, Chennai Metro, Indian Railways

• Water Supply and Sewerage Tunnels-Local Municipal Bodies

• Total Hydropower Potential-84,044 MW

• The Himalayan Terrain

• Resources Required in Future Tunnels- INR 732,000,000,000/-

• 18000 Skilled Manpower by 2017 for around 600 Tunnels

• INR 24 Billion worth of Machinery and Equipment by 2017

Source: Central Board of Irrigation and Power

Procurement-Major Manufacturers

Italy Germany

United States Switzerland

Parts and Operation of a TBM Video

TBM Utilization

Suitability of the TBM

Performance of a TBM

Factors Determining Performance of a TBM: • Instantaneous penetration rates(P), measured in mm/rev or m/hr for

only the time TBM spends cutting the ground.

• TBM Utilization(U %), proportion of time spent cutting expressed as an avg. of the total available working time (T in hrs/weeks).

• Cutting Rate Consumption (20 to 200 m3 /mining hr)or Cutter Cost &

• Delays for tunnelling through major geological features where this is measurable in days or weeks.

• TBM advance rates(m/week) are predicted by the relationship:

o Advance Rate= Distance Mined / Shift Time (in m/week)

o TBM Productivity on an average for 3.5m Dia. TBM is 130m/week but World Record is 703m in a week by Robbins TBM (Katoomba Carrier in Australia).

Advantages

• Major Advantages

o cost savings resulting from qualitative advantages of mechanical

excavation

o TBM excavation rates four to six times higher than D&B excavation

o Over-break (cost of delivered concrete, wastage and labour to fill

over-break)

o labour crew costs

o associated supplies (drill bits, TBM cutters, blasting agent)

o support costs

o elimination of temporary construction structures (access adits

and/or shafts)

Advantages

• Operational Advantages

o structural stability and safety at the face and work area

o continuous (non-cyclic) operation

o consistent, less skilled and easily trained operations (labour is assigned to

limited tasks that are repetitive, become routine, and may even produce

competition among the labourers)

o safer and more pleasant working environment than in D&B

• Safety

• Continuity of Operation

• Skilled Labour Advantages

• Performance Advantages

Risks Involved in the TBM

• Soil Cave-in and Cavities

• Fluctuating Productivity

• Break Down & Maintenance Losses

• Proper Soil Investigation not done

• Non availability of support services

TBM as an alternative to DBM

Site Photographs-KGHEP, Kashmir

Thank You!