What is the primary factor for selecting a TBM?

The geological and hydrogeological conditions of the ground to be excavated are the most critical factors (Clause 5.2 and Table 1).

What are the common types of linings used with TBMs?

Precast concrete segmental linings are the most common. In-situ concrete or steel ribs may also be used in specific conditions (Clause 6.2).

What is the purpose of backfill grouting?

To fill the annular void between the excavated ground and the segmental lining, transfer ground loads to the lining, and prevent water ingress (Clause 7.5).

What level of geotechnical investigation is required?

A detailed investigation is mandatory, covering geology, rock/soil mechanics, and hydrogeology to create a reliable geotechnical model for TBM selection and design (Clause 4).

IS 13783 Part 2

: 1993

Guidelines for design and construction of large diameter tunnels (Part 2: Tunnel boring machine (TBM) method)

CurrentSpecializedGuidelinesBIMGeotechnical · Tunneling and Underground Structures

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This standard provides guidelines for the design and construction of large diameter tunnels using the Tunnel Boring Machine (TBM) method. It covers critical aspects from geotechnical investigations and TBM selection to the design of segmental linings and construction procedures, focusing on ensuring stability and safety.

Provides guidelines for the design and construction of large diameter tunnels specifically using Tunnel Boring Machine (TBM) methods.

Quick Reference Values

Typical allowable deviation in tunnel alignment±50 mm to ±100 mm

Typical annular gap for backfill grouting150 mm to 250 mm

Typical grout pressure1.5 to 2.0 times the overburden pressure

Minimum thickness of precast concrete segmentsGenerally not less than 150 mm, or D/50 (D=tunnel dia)

Minimum cover for tunneling under structuresOften > 1.5 times the tunnel diameter, project-specific

Practical Notes

Selection of the correct TBM type (e.g., Earth Pressure Balance, Slurry Shield, Open Gripper) based on thorough geotechnical investigation is the single most critical factor for project success.

The design of segmental lining is an iterative process involving analysis of ground-structure interaction, handling/erection stresses, and long-term durability requirements.

Continuous monitoring of ground settlement, TBM operational parameters (e.g., face pressure, torque), and lining integrity is essential throughout the construction phase.