Concepts and Instruments for Improved Monitoring

It is shown that a good instrumentation strategy, based on reliable measurements of displacements and pressures, is necessary for monitoring the safety and the behavior of civil works during construction and operation. A significant step forward was achieved by the development of a new generation of instruments. Constant tension invar wires give best accuracy of distance measurements for minimal interference with construction works or operation. Continuous piezometers for boreholes allow precise landslide monitoring and proper remedial works implementation. Vibrating wire sensors have been used in strainmeters and in pressure cells for many years, and their reliability is proved. Recently developed self-inductance sensors allow more sensitive and accurate monitoring. Successful experience on a number of large projects show that electronic equipment can best satisfy all the conditions of a good instrumentation, and results in an improved overall safety at least cost.