Problems of the geodynamic effect on large dams

Abstract

1. High-head dams in seismic and mountain regions are constantly subjected to geodynamic loads — slow or rapid tectonic movements, creep, changes in hydrogeodynamic pressure — not taken into account in the designs. This circumstance as well as an increase of the standard seismicity in regions of certain dams require improvement of the system monitoring dangerous geodynamic processes and methods of predicting and modeling them. 2. Monitoring of the geodynamic effect on the stress — strain state and safety of dams can be realized by means of the traditional embedded instruments, provided their modernization and automation. 3. A priority role should be given to a study of induced seismicity as an objectively existing dynamic load, the action of which was not taken into account earlier in the SNiP and designs. Knowledge of the mechanism of induced seismicity and methods of predicting it will help in investigations of the mechanism of strong natural earthquakes. 4. New automated measuring instruments made it possible to detect low-frequency, long-period dynamic effects on structures from the surrounding geological environment. It can be assumed that they have a seismogenic character. This type of quasi-static loads is not recorded by seismometric apparatus and should be monitored and studied by automating the traditional embedded monitoring and measuring instruments synchronized with the seismological apparatus. 5. On-site observations on dams with a height of 60 m and more should be carried out with mandatory consideration of geodynamic effects and accumulation of a data bank on parameters of earthquakes, their precursors and aftereffects. A retrospective analysis of the response of the dam to early earthquakes and a constantly updated data bank will make it possible to solve the problem of predicting dangerous geodynamic processes and to develop mathematical models for taking into account induced seismicity and other geodynamic loads when designing high dams in seismic and mountain regions.