Abstract
An experimental study was carried out to investigate the acoustic emission (AE) characteristics of dry and saturated basalt columnar joints under uniaxial compression and tensile damage by using the TAW-2000 rock experiment system and SH-IIAE system for the whole loading. The results show that the softening coefficient of uniaxial compressive strength and the tensile strength was 0.78 and 0.68, respectively, and water increases the sample complexity and has a strong effect on its strength. The dry sample under uniaxial compression at the beginning of loading produced a large number of AE signals, and the AE signal showed steady growth as the load increased, but the sample destruction occurred during the blank period, which can be used as a precursor of instability. From the amplitude-time-energy diagram, it can be found that as amplitude increases with hit, energy decreases, which shows an obvious triangle relation. From the uniaxial compression damage AE location map, we can find that AE events exist disorderly and show scattered distribution in each area. From the failure modes and sections of tension and uniaxial compression tests, it is found that there are many layers and fissures in rock samples, which are consistent with AE location.
Highlights
In the process of underground tunnel excavation, dynamic disasters mainly rock burst and tunnel collapse occur. ey are caused mainly by combination of tension and compression stress; the rock tensile strength has far less effect than the compressive strength, but the tensile stress is the primary reason for failure
The basalt columnar joint will be in dry state, and the rock mass will be damaged during excavation and unloading
The rock mass will be damaged, and it will be damaged under the action of the external load; the laboratory experiment is the mechanical experiment of the basalt columnar joints conducted under dry and saturated water conditions. is affects the whole project progress speed, so it is very necessary to study the characteristics of basalt columnar joints of the diversion tunnel rock, the nature of which is changed by the running water
Summary
In the process of underground tunnel excavation, dynamic disasters mainly rock burst and tunnel collapse occur. ey are caused mainly by combination of tension and compression stress; the rock tensile strength has far less effect than the compressive strength, but the tensile stress is the primary reason for failure. Erefore, this article studies the AE monitoring of the whole process of basalt columnar joints damage to know the characteristic of AE of rock failure process, which provides the theoretical basis for the AE prediction. Zhang et al [2] carried out AE experiments on water-bearing sandstone under uniaxial loading and discussed the changes of natural state, frequency, and energy of water-bearing rock. Ere are only few research studies on physical and mechanical properties of basalt columnar joints; this article investigates the AE monitoring of basalt columnar joints destruction under uniaxial compression and tensile damage experiment. E stability of columnar jointed basalt in Baihetan Hydropower Station dam area under saturated condition is studied, which can provide some guidance for dam foundation, underground chamber construction, and water-related rock mass engineering problems with abundant columnar jointed basalt By analyzing the damage situation, AE parameters, and rock’s damage AE precursor information, this study provides theoretical support for field monitoring. e stability of columnar jointed basalt in Baihetan Hydropower Station dam area under saturated condition is studied, which can provide some guidance for dam foundation, underground chamber construction, and water-related rock mass engineering problems with abundant columnar jointed basalt
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