Experimental Study On The Rate Of Rock Kaiser Effect Of Load

The measurement of initial stress in rocks is the premise of all kinds of rock engineering, including open-pit and underground mining. Unfortunately, the known stress measurement techniques are time and labor-consuming, and the measurement accuracy cannot meet the requirements of engineering design and construction. Therefore some simpler and cheaper technique is needed. The technique based on Kaiser effect of acoustic emission (AE) is just a simpler one, cost much less and can proceed much more tests. However, it is found in the previous studies that this technique concerns quite a few factors that needs more detail investigations, such as the direction of the applied stress, time delay, loading rate and so on.As we know, in the rock mechanics experiment, it usually uses the acceptable stress rate or strain rate to add and uninstall, and so the loading rate of memory may be formed with the stress rate is different. So it is a great significance of choosing the appropriate loading rate to study the Kaiser effect of rock.The control system composed of the TAW-2000D microcomputer-controlled electro-hydraulic servo rock triaxial testing machine and a testing apparatus of AE, SDAES can realize that the computer controls loading rate and collect real time signal, and through the software converts electrical signals into the test data. The paper chooses the suitable loading rate to prove the Kaiser effect of rock by comparing characteristics of the rock acoustic emission and deformation in the three loading rate, and then through the experimental research on the Kaiser effect of rock in the loading rate to set the best value range of loading rate. At last the test use the Kaiser effect of rock to imitate the loading rate.Through the analysis of test results, the following conclusions are obtained:(1) Under the condition of uniaxial compression, the rock of the destruction mechanism affected by the loading rate has different performance in the elastic stage and crack extension stage; the faster the loading rate is, the longer the duration of the energy is, and the more ringing count in a single event is;(2) By comparing of the deformation and failure characteristics of rock under different loading rate, the conventional loading rate can show big various stages of tuff in the process of damage;(3) Under the condition of uniaxial compression the tuff exists Kaiser effect, but it is associated with the percentage of rock strength, and Located in mainly between30%and75%of rock breaking strength;(4) When loading rate is faster and faster, the value of FR is biger and biger. When the error scope of FR is no more than1%, rock loading rate values in the range of0.58-0.80MPa/s;(5) In loops and unloading tests, when the damage degree of rock is greater and greater, the Felicity effect is more and more obvious with increasing stress;(6) Through the indoor experiments of of using Kaiser effect to simulate live loading rate, the preliminary is obtained that the conventional stress loading rate can be better expressed early memory of the maximum stress level under different stress rates.