Abstract：Acoustic emission(AE) tests are performed on rock samples under uniaxial compression with and without seepage flow，respectively；and four kinds of rock¢s AE characteristics are identified and analyzed. Results of the AE tests show that，at lower stress levels，almost no AE occurs in the rock and the seepage flow has little effect on AE activities. However，when the compressive stress reaches to the value of 60%–80% of rock strength，the AE activities increase remarkably. Drastic AE events occur at the moment when the seepage flow is loaded or unloaded and almost no AE signals are able to be received when the seepage flow is unloaded in steady state. Rock breakage process can be divided into four phases according to its AE characteristics，that is，beginning phase，tempestuous phase，drop phase and dreary phase. During rock breakage，dominant frequency of rock AE is broader than that of intact rock，where the percentage of low frequencies exceeds 50% without seepage flow through the rock. Comparing the dominant frequency of hard rock¢s AE to those before and after its breakage，the maximal dominant frequency during breakage increases remarkably. However，the percentage of low frequencies exceeds 60%–80% for rocks with seepage flow through them or marinated for a long time(about 130 h)，and the maximal dominant frequency of intenerated rock does not change significantly. Furthermore，the dominant frequency of rock AE varies with the rock strength；the larger the strength is，the broader the dominant frequency is. With the increase of the compressive stress，the maximal dominant frequency exhibits an increasing trend for some kinds of rocks.
