Experimental Study Of Acoustic Emission’s Factors Of Chongqing Sandstone In Three-point Bending Test Conditions

In recent years, due to the need for water conservancy and hydropower engineering, mining, civil engineering, railway bridges, roads and tunnels, rock acoustic emission(AE)characteristics for research has always been a very important issue. Especially the study on Kaiser effect of rock, such as the judgment methods of the Kaiser point research, research of rock Felicity effect and Felicity ratio, and the study of memory effect of rock, has been favored by domestic and foreign scholars to a certain extent. Factors affecting the rock AE characteristics and Kaiser effect is increasingly becoming a topic of concern, such as the size effects, temperature effects, loading rate, loading mode, homogeneity and environmental effects. Although research in this area has a lot, but the rock AE characteristics and influencing factors of Kaiser effect remains to be further studied.This paper mainly through experiments and numerical simulation analysis of the influence factors of C hongqing sandstone AE characteristics and Kaiser effect in three point bending experiments. The control system composed of the TAW–2000D microcomputer-controlled electro-hydraulic servo rock tri axial testing machine and a testing apparatus of AE, DS2 can realize that the computer controls and collect real time signal,and through the software converts electrical signals into the test data. The test mainly has conducted the research to the size effect, loading rate, different material homogeneity and loading methods, to observe and discuss these experimental conditions of AE characteristics and the presence of the Kaiser effect, and to discuss the memory effect of rock. The numerical test is used in RFPA-BASIC to analysis failure process and AE characteristics through considering the size effect, loading rate,different material homogeneity and loading mode.Through comparing and analysis of the results of laboratory tests and numerical simulation results, we can draw the following conclusions: 1) the numerical simulation results and actual test are in agreement with the phenomenon, AE law is also basically same, the Kaier effect phenomenon is obvious, but compared with the test, the obtaining numerical results for the Felicity ratio is greater than one, the memory effect is lagging behind. 2) AE characteristics and Kaiser effect of sandstone in the three-point bending test conditions are affected by the size of the effect, the greater the sample size, when the destruction of sandstone needs greater energy. 3) Comparing the granite and mortar with sandstone,the strength of the material is greater, the accumulated number of AE is greater, and AE energy is also more; The degree of homogeneous materials is smaller, the cumulative AE number and accumulative number are more. 4) From the loading methods, Comparing with the three-point bending test condition,the producing cumulative AE counts of sandstone in uniaxial compression and splitting test conditions are greater, and the releasing energy is also greater.