ACOUSTIC-EMISSION DURING SWELLING AND CONTRACTION TESTS

An expansive clayey rock belonging to the Asturias Carboniferous of NW Spain has been petrophysically characterized before, during and after swelling tests. The evolution of the microfissuring and the induced d eterioration have been studied by acoustic emission during tests and b y ultrasonic techniques before and after swelling/contraction cycles. A good correlation has been found between the AE curves and swelling s train. Damage due to the generation and growth of microfissures is mos t important during the first moments of each swelling/contraction cycl e. Microfissures mainly develop in the direction of the foliation plan es, as can be shown by linear crack density and measurements of the pr opagation velocity of longitudinal waves.