砂岩单轴循环加卸载试验及声发射特征研究

Sandstone Uniaxial Cyclic Loading Tests and Acoustic Emission Characteristics

通过对砂岩进行循环加载试验,揭示了砂岩在循环加卸载过程中的强度变化及声发射特性。试验利用电液伺服岩石三轴试验机和SDAES数字声发射检测仪采集系统,对两组砂岩试样分别进行单轴抗压、单轴循环加卸载试验。试验结果表明岩样在经过循环加卸载后试样的单轴抗压强度略有增大,循环加卸载过程中在伴随着岩样内部原始天然裂隙的压密、新生裂纹的产生、扩展和贯通的同时,也伴随着声发射不断产生。声发射事件在砂岩再次加载应力到达上次加载最大应力前极少发生,达到上次加载最大应力以后则大量发生,说明砂岩岩样在循环加卸在作用下存在声发射的Kaiser效应,而无Felicity效应产生。

This paper studies the sandstone and sound intensity changes in the process of loading and unloading cycle emission characteristics based on the sandstone cyclic loading tests. Electro-hydraulic servo triaxial testing machine and SDAES digital acoustic emission detector acquisition system are applied. Two sandstone samples are subjected to uniaxial compressive uniaxial cyclic loading test. Testing results show that the rock sample after cyclic loading and unloading after the sample is uniaxial compressive strength increases slightly. The same cyclic loading and unloading process is observed of having compaction, resulting in cracks in the rock sample nascent internal raw natural fissures, expansion and penetration, accompanied by the continuous generation of acoustic emission. In addition, after unloading sand again last loaded before loading stress reaches the maximum stress acoustic emission events occur only rarely. Loading stress reaches a large amount of new acoustic emission event after the last load of maximum stress proved sandstone samples in circulation unloading presence Kaiser effect of acoustic emission in the role, without Felicity effect produced.