16.12. INSTRUMENTATION The behaviour of concrete gravity dam as well as its foundation is observed through suitable instruments during the periods of construction, reservoir filling, and operation of the reservoir. Instruments are employed for measurements of strain, temperature, stress, deflection, and deformation of the foundation. The data obtained from various instruments are helpful not only for assessing the safety of the structure during construction as well as operation periods, but, also for future design and operational studies.
The instruments (or the methods) employed for obtaining information on the behaviour of a concrete dam and its foundation can be broadly classified into two categories. The first category includes such instruments as are either embedded in the concrete mass of the structure or placed on surface of the dam and its appurtenant structures. Such instruments measure strain, stress, contraction joint opening, temperature, concrete pore pressures, and foundation or deformation. The second category of instruments include precise surveying instruments which make measurements of horizontal and/or vertical deformation using targets located on the downstream face or top of a dam, inside the galleries and vertical wells in a dam, in tunnels, and on the abutments.
