1998 – Monitoring Dam Performance Using Tiltmeters

M O’Reilly, S A L Read and P F Foster

Electronic (bubble) tiltmeters provide an up-to-date technique for continuously monitoring the deformations of dam and dam-related structures. Tiltmeters, with a sensitivity of (10Imm per length), are currently used in New Zealand at the high concrete gravity Waitaki Dam, and the Ohau A Powerhouse, as well as a short-term installation in the high concrete gravity Aviemore Dam.

This paper outlines the performance of the tiltmeters over a period of up to 7 years. They have been used to monitor the reactions of structures to loading changes such as headwater level variation, and to monitor ongoing performance, including the definition of annual thermal cycles. The results are compared with other monitoring techniques (e.g. plumblines, conventional surveying) to illustrate the usefulness and applicability of tiltmeters to dam safety programmes, either in conjunction with standard monitoring options, or in particular where such options may not be practicable.