IS 15124:2002 is the Indian Standard (BIS) for guidelines for construction of underground structures using new austrian tunneling method (natm). This standard provides guidelines for the design and construction of tunnels and other underground structures using the New Austrian Tunneling Method (NATM). It covers the core principles, including the use of observational data, sequential excavation, and flexible support systems like shotcrete and rock bolts to mobilize the strength of the surrounding ground mass.
Provides guidelines for the design and construction of underground structures, including tunnels, using the New Austrian Tunneling Method (NATM).
BIM-relevant code. See the BIM Hub for ISO 19650, IFC, and LOD/LOIN frameworks used alongside it.
| Parameter | IS Value | International | Source |
|---|---|---|---|
| Shotcrete Compressive Strength (28-day) | Recommends grades like M25 to M35 (25-35 MPa), to be specified by the designer. | Specifies strength classes, e.g., C25/30 or C30/37 (25 or 30 MPa characteristic cylinder strength). | ITA Report 019:2020 (referencing Eurocode 2) |
| Shotcrete Early Strength Class | Not formally defined; general requirement for early strength gain. | Defined classes like J1, J2, J3 based on strength vs. time curve (e.g., J2: ≥10 MPa at 24 hours). | ÖNORM B 2203-1:2018 |
| Primary Lining Shotcrete Thickness | Design-dependent, typically 50mm to >250mm based on rock class. | Often specified in support-class tables, e.g., 'Class A: 150mm', 'Class B: 200mm'. | ÖNORM B 2203-1:2018 |
| Waterproofing Membrane Thickness | Recommends use but does not specify thickness (typically 2.0 mm in practice). | Minimum thickness is often specified, e.g., '2.0 mm' for PVC or HDPE sheets. | BTS Specification for Tunnelling, 4th Ed. |
| Convergence Monitoring Frequency (Initial) | Left to designer's discretion; typically once per shift after installation. | Often specified contractually, e.g., '3 readings within first 24 hrs, then daily for 3 days'. | BTS Specification for Tunnelling, 4th Ed. |
| Shotcrete Toughness/Energy Absorption | Not explicitly specified; may refer to fiber dosage. | Specifies required energy absorption values from panel tests (e.g., 700 Joules for Class E700). | ITA Report 019:2020 |