THE SWAYING PROBLEM OF UNIVERSAL TESTING MACHINE IN THE MEASUREMENT OF ROCK STRESS BY AE METHOD DING Yuan-chen,WANG Xi-hai,HE Pei-yuan

In the measurement for memorized rock stress by AE method,the symmetrical disturbance for AE in limited receiving scope comes from the fraction between endsurfaces of specimen and pressure heads of universal testing machine.The magnitude and change of the disturbauce for AE can be obtained by the measurement of swaying magnitude and change of test rig of universal testing machine in the process for uniaxial compression test.The measuring results show that the sway and the corresponding disturbance for AE are all remarkable in the beginning stage of compressing specimen.The methods and the viewpoints for overcoming the symmetrical disturbance for AE are given by authors on the basis of the level for the measurement at present.