1. NATM
NEW AUSTRIAN TUNNELING METHOD

2. HISTORY OF NATM
The term New Austrian Tunneling Method Popularly Known as NATM got its name from Salzburg (Austria).
It was first used by Mr Rabcewicz in It got world wise recognition in1964.
The first use of NATM in soft ground tunnel in Frankfurt (Europe) metro in 1969.
The basic aim of NATM is for getting stable and economic tunnel support systems.

3. DEFINITION OF NATM
The New Austrian Tunnelling Method is a support method to stabilize the tunnel perimeter by means of sprayed concrete ,anchors and other support and uses monitoring too control stability.

4. BROAD PRINCIPLES OF NATM
Mobilization of the strength of rock mass
Shotcrete protection
Measurements
Primary Lining
Rock mass classification
Dynamic Design

5. WHY NATM
Flexibility to adopt different excavation geometries and very large cross sections.
Flexibility to install additional support measures, rock bolts, dowels, steel ribs if required.
Easy to install a waterproof membrane.
Easy to install primary support, i.e. shotcrete.
TBM (Tunnel Boring Machine) is not an effective method as compared to NATM .

6. SUMMARY OF THE PROCEDURE IN NATM
SHOTCRETING AT THE EXCAVATED AREA(PRIMARY LINING)
PLACING OF THE WIREMESH ALONG THE FACEOF THE TUNNEL
ERECTION OF THE LATTICE GIRDER ALONG THE FACE OF THE TUNNEL
PERTICULAR TYPE OF ROCKBOLTING
SHOTCRETING THE WHOLE ARRENGEMENT(SECONDARY LINING)

7. SEQUENCE OF EXECUTION OF NATM

13. CONCEPT OF 3D MONITORING
3D MONITORING IS NEW TECHNIQUE USING FOR TAKING THE RIGHT ALIGNMENT OF THE TUNNEL
OPTICAL TARGETS ARE USED FOR DETRMINIG THE COORDINATES FOR MEASUREMENTS
THE COORDINATES SHOULD BE CHECKED DAILY
IT IS NECESSARY FOR THE TUNNEL AS BY IT WE KNOW ANY DISPLACEMENT AND WRONG ALIGNMENTS

14. General
Optical Target

16. General
Optical Displacement Monitoring
Free Stationing

17. POINTS TO CARRY OUT A SUCCESSFUL NATM PROCESS
Consideration of rock mechanics
Selection of a proper profile
Design of flexible support and slender lining (in rock)
Careful excavation
Maintenance of rock strength, avoidance of loosening and over-breaks
Direct contact of rock/soil and support
Continuous control by geotechnical measurements
Installation of support without delay and in correct
sequence

18. WHERE NATM IS USING IN INDIA
PRESENTLY IT IS USING WIDLELY IN KASHMIR RAILWAY PROJECT
THEY ARE USING IT IN THEIR TUNNELS LIKE IN PIR PANJAL TUNNEL , T-74R, T-48 ETC

19. THANK YOU FOR YOUR ATTENTION!