THE AIM OF THE RESEARCH IS TO STUDY EXPERIMENTALLY THE DIFFERENT STAGES IN THE HISTORY OF SALT DOMES (OR DIAPIRS). IT COMPLETES A PREVIOUS CEC CONTRACT WHICH ENDED BY AUTUMN 85. THE MAJOR PART OF THE WORK IS THE INCLUSION OF THREE DIMENSIONAL MODELS FOR COMPARISON WITH TWO DIMENSIONAL ONES OF THE FIRST PERIOD.

TESTS ARE PERFORMED ON EQUIVALENT MATERIALS ON THE LARGE CENTRIFUGE OF CESTA (IN BORDEAUX). RESULTS CAN BE APPLIED TO DOME EVOLUTION THROUGH SIMILITUDE TRANSPOSITION. THE PURPOSE OF THESE EXPERIMENTS IS TO RECORD THE MAIN ONSET AND DEVELOPMENT MECHANISMS OF SALT DIAPIRS.
Centrifuge simulations were used to investigate long term instabilities in salt formations containing stored radioactive waste. The same materials (clay, loaded clay and gelatine) were used throughout.

3 dimensional models of the same width as 2 dimensional ones were introduced to verify results obtained with the latter. A system employing electro-osmosis to cut the clay was developed. 2 dimensional tests were conducted to reveal the causes of instabilities, their propagation and the part played by jets and fissures. The 3 dimensional tests confirmed the results of the 2 dimensional tests both for trigger points and for the shapes of the diapiric folds, at a more rapid rate.
1. TWO-DIMENSIONAL TESTS: DIFFERENT POSSIBLE STARTING FACTORS OF MOVEMENT ARE TESTED.

2. THREE-DIMENSIONAL TESTS: COMPARABLE TESTS WITH TWO-DIMENSIONAL ONES ARE PERFORMED.