| Title | A new setup for studying thermal microcracking through acoustic emission monitoring |
|---|---|
| Authors | Griffiths, L; Heap, M J; Baud, P; Schmittbuhl, J |
| Year | 2016 |
| Conference | European Geothermal Congress |
| Keywords | thermal cracking, microcracks, acoustic emissions |
| Abstract | Thermal stressing has been shown to induce changes in the physical and mechanical properties of rocks. These changes are generally considered to be a consequence of the generation of thermal microcracks and debilitating chemical reactions. The generation of cracks during thermal stressing has been monitored in previous studies using the output of acoustic emissions (AE), commonly used as a proxy for microcrack damage, and from microstructural observations. Here we present a new experimental setup that is optimised to record AE from a rock sample at high temperatures and under a servo-controlled uniaxial stress. This allows for an in-depth study of waveform attributes. Furthermore, this device has the advantage of being able to apply a servo-controlled load on the sample, whilst measuring strain in real time, leading to a spectrum of possible tests combining mechanical and thermal stress. We plan a systematic experimental study of the AE of thermally stressed rock during heating and cooling cycles. The first series of pilot tests were performed on Darley Dale sandstone and Westerly granite. |