Mechanical properties of columnar jointed basalt rock with hidden fissures under uniaxial loading
HU Wei1，WU Aiqing1，CHEN Shenghong2，HUANG Shuling1，ZHANG Lijie1
(1. Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources，Yangtze River Scientific Research Institute，Wuhan，Hubei 430010，China；2. State Key Laboratory of Water Resources and Hydropower Engineering
Science，Wuhan University，Wuhan，Hubei 430072，China)
Abstract：A set of uniaxial compression tests has been carried out on the samples of basalt rock with hidden fissures and the acoustic emission signals have been monitored during the test processes. The failure characteritic of samples under the compression loads are affected by the hidden fissures and the failure mode is primarily the shear-tension failure that the cracks propagated from the tips of hidden fissures，then slide beside the cracks. The hidden fissures cause the stress-strain curve to exhibit a “saw tooth” shape during the failure stage. The average uniaxial compression strength of the tested samples is 106 MPa and lower than the intact aphanitic basalt rock from the same site. The more of fissures within a sample，the lower the strength. The characteristics of acoustic emission signals are affected by the type of strain. The energy acoustic emission caused by the permanent strain has a higher amplitude. The acoustic emission develops steadily before failure，and increases greatly after entering the failure stage. The signal intensity of acoustic emission decreases by the hidden fissures inside the specimens，but the absorption effect dropps when the fissures close under compression.