An Engineering Approach To Monitoring The Performance Of Soft Ground Tunnels During Construction

INTRODUCTION To be effective and useful, monitoring of tunnel construction must be carefully planned throughout all steps. A vital and frequently overlooked step is a clear definition of the specific purposes of the instrumentation. Most tunnel construction monitoring has in the past been of benefit to research, the advancement of tunneling practice, wittingly or not. The development of monitoring instrumentation for the benefit of the project from which the data are recovered has very significant potential for risk and cost reduction of soft ground tunneling. A systematic approach to tunnel construction monitoring, from conception to full implementation, includes at least the following nine tasks or steps: Definition of benefits and purposes; design and project specification to draw full benefits; selection of monitoring parameters; selection of instruments and writing of specifications for procurement and installation; procurement and installation; reading and maintenance; data storage and retrieval; interpretation; implementation. Some of these steps are fairly easy and resolved through the use of established theories and technologies. The difficult ones are those that require the bending of minds, those that involve changes in the ways engineers design soft ground tunnels, the way owners pay for tunnels, and the construction is managed, inspected and controlled. Performance monitoring can be of benefit to the owner, design