IS 2770:1993 Part 2 is the Indian Standard (BIS) for safety code for tunnelling work: part 2 working in soft ground. This standard prescribes safety measures for tunnelling operations in soft ground conditions. It covers essential precautions for excavation, temporary supports (shoring/timbering), ventilation, gas monitoring, and dewatering to prevent cave-ins and ensure worker safety.
Lays down safety requirements for tunnelling operations specifically in soft ground, covering methods, ground stabilization, and support.
Overview
- Status
- Current
- Usage level
- Specialized
- Domain
- Geotechnical — Construction Safety and Practices
- Type
- Safety Code
Also on InfraLens for IS 2770
Practical Notes
! Ensure immediate installation of temporary supports (timbering or steel ribs) right after excavation to prevent sudden face collapse.
! Continuous monitoring for ground settlement and toxic/explosive gases is mandatory in soft soil strata.
! Dewatering must be carefully managed to avoid excessive surface subsidence or instability of adjacent structures.
Frequently referenced clauses
soft groundsoiltimbershotcretesteel
International Equivalents
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Key Values4
Quick Reference Values
minimum ventilation rate6 m³/min per person
max permissible methane concentration1.25%
max voltage for portable lighting24 V
minimum illumination at working face50 Lux
Tables & Referenced Sections
Key Clauses
Clause 4 - Precautions during Excavation in Soft Ground
Clause 5 - Timbering, Shoring and Temporary Supports
Clause 6 - Ventilation and Gas Monitoring
Clause 7 - Dewatering and Groundwater Control
Clause 8 - Emergency Exits and Rescue Procedures
Frequently Asked Questions3
What is the minimum fresh air supply required in the tunnel?+
A minimum of 6 cubic meters per minute per worker must be supplied to ensure a safe breathing atmosphere.
What is the maximum allowed methane concentration?+
All work must be halted and personnel evacuated if the methane concentration in the tunnel exceeds 1.25%.
What is the safe operating voltage for portable lighting in underground wet conditions?+
Portable hand lamps must operate at a maximum of 24 Volts to prevent electrocution in highly conductive environments.
QA/QC Inspection Templates
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QA/QC templates coming soon for this code.