Principles of the NATM and other uses of the geologic monitoring techniques

The NATM (New Austrian Tunneling Method) differs in several respects from other construction methods. Also referred to as the open-quotes sequential method,close quotes or the open-quotes observational tunneling method,close quotes NATM offers outstanding flexibility by extending the design into the construction phase. Geologic monitoring of the underground opening (tunnel, shaft or cavern) on an on-going basis provides the means by which the precise support measures and tunnel advance sequence may be matched to varying rock conditions. The pragmatic principles, developed and perfected by NATM Engineers, depend upon sophisticated in situ monitoring of rock conditions on an ongoing basis. These same monitoring techniques, born of the need to determine safe, efficient ground support, are also utilized in the long term checking of existing tunnels. In addition, the instrumentation and program systems of NATM can provide accurate measurements to meet many of the site characterization requirements of underground nuclear repositories even when employed in combination with mechanical excavation