NATM NEW AUSTRIAN TUNNELING METHOD. HISTORY OF NATM The term New Austrian Tunneling Method...
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NATM NEW AUSTRIAN TUNNELING METHOD. HISTORY OF NATM The term New Austrian Tunneling Method Popularly Known as NATM got its name from Salzburg (Austria)
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 1962. 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.
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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.
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BROAD PRINCIPLES OF NATM Mobilization of the strength of rock
mass Shotcrete protection Measurements Primary Lining Rock mass
classification Dynamic Design
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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.
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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)
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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
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General Optical Target
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General Optical Displacement Monitoring Free Stationing
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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
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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