Acoustic emission fractal characteristics of different prefabricated fractured sandstone under uniaxial compression tests

2021 ◽  
Author(s):  
Min Deng ◽  
Zizheng Zhang ◽  
Jinlin Xin ◽  
Weijian Yu ◽  
Xianyang Yu
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Compression Tests ◽  
Fractal Characteristics ◽  
Fractured Sandstone

scholarly journals Dual role of microcracks: toughening and degradation

2001 ◽  
Vol 38 (2) ◽  
pp. 427-440 ◽  
Author(s):  
G M Nagaraja Rao ◽  
C RL Murthy
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Inelastic Strain ◽  
Dual Role ◽  
Compression Tests ◽  
Defective Structure ◽  
Heating And Cooling ◽  
Thermally Treated

One of the methods of improving the mechanical properties of ceramics is to introduce a defective structure that acts as a restraint for the propagation of cracks. In the present study a detailed investigation was carried out by introducing a defective structure in rock to determine if there is any improvement in properties similar to ceramics. Granite was chosen for the investigation, and the microcracks were introduced by a heating and cooling cycle. Uniaxial compression tests have shown that granite thermally treated to 200°C shows the highest strength, and the strength of granite treated to 400°C is comparable to that of unheated granite. Both ultrasonic images and acoustic-emission monitoring show that for thermally treated samples the stress-induced microcrack and macrocrack nucleation and their growth are retarded. The variations in mechanical properties are explained based on the concept of toughening and degradation. Uniaxial compression tests on unheated and thermally treated granite samples have clearly established the dual role of microcracks, which operate in the toughening and degradation mechanisms.Key words: thermal treatment, microcrack, inelastic strain, ultrasonic C-scan imaging, acoustic emission, toughening.

Research on the AE Characteristic of the Rock with Rockburst Proneness

2014 ◽  
Vol 608-609 ◽  
pp. 689-692
Author(s):  
Mo Xiao Li ◽  
Guang Zhang ◽  
Jing Xi Chen
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Rock Mechanics ◽  
Compression Tests ◽  
Entire Process ◽  
The Relationship ◽  
Ae Signals

In this paper, in order to strengthen the prediction of rockburst and inquire the relationship between the rockburst proneness of rock and its AE characteristic, each kind of typical rock of volcanic, sedimentary and metamorphic were selected to doing indoor rock mechanics experiments. Calculate the rockburst proneness of these rocks by uniaxial compression tests. In uniaxial compression, we collect the entire process of AE signals by using acoustic emission instrument, then we analysis the AE characteristics of different rocks to inquire the relationship between the AE characteristic and its rockburst proneness.

scholarly journals Experimental Study on Acoustic Emission Characteristics of Dry and Saturated Basalt Columnar Joints under Uniaxial Compression and Tensile Damage

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Liu Gang ◽  
Xiao Fu-kun ◽  
Cheng Qian-long ◽  
Qin Tao
Keyword(s):  
Experimental Study ◽  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Failure Modes ◽  
Compression Tests ◽  
Steady Growth ◽  
Columnar Joints ◽  
Ae Location ◽  
Location Map ◽  
Tensile Damage

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.

scholarly journals Study on Acoustic Emission Characteristics of a Semirigid Base of Dense Skeleton Type during Complete Uniaxial Compression Tests

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Shengli Li ◽  
Guangming Wu ◽  
Hao Wu
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Growth Stage ◽  
Failure Process ◽  
Testing Machine ◽  
Compression Tests ◽  
Stage Of Development ◽  
General Terms ◽  
Initial Stage ◽  
Stable Growth

Acoustic emission testing of semirigid base specimens subjected to uniaxial compression was performed by a mechanical testing machine and AE system to find the AE criterion of the uniaxial compressive failure process of the semirigid base of dense skeleton types. AE counts, cumulative AE energy, andb-value were discussed. Results indicated that the AE parameters could reflect the failure process of semirigid bases of dense skeleton types. The failure process mainly underwent three stages that were divided based on AE parameters into initial stage of development, stable growth stage, and unstable stage. The knees of the AE parameter curve were at 25% and 85% of the ultimate load. The variation of theb-value could indicate the stress and be a precursor to the failure of the specimens. In general terms, ab-value greater than 3.5 indicates that specimens are at the initial stage of development. Ab-value between 1 and 2 indicates that the specimens are at the stable growth stage. If theb-value seems to fluctuate and increase, the specimens are at the unstable stage. Moreover, the AE parameters indicated that attaching sensors to the waist of specimens was superior to that at other locations of a specimen.

scholarly journals Experimental Investigation of Progressive Failure Processes Using 3D Acoustic Emission Tomography

2021 ◽  
Vol 9 ◽  
Author(s):  
Yan Cheng ◽  
Paul Hagan ◽  
Rudrajit Mitra ◽  
Shuren Wang ◽  
Hong-Wei Yang
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Failure Modes ◽  
Progressive Failure ◽  
Three Dimensional ◽  
Stress Conditions ◽  
Compression Tests ◽  
Tomographic Images ◽  
Fracture Development ◽  
Ae Counts

In this paper, the potential of 3D acoustic emission (AE) tomography technique in demonstrating fracture development and delineating stress conditions was examined. Brazilian tests and uniaxial compression tests were monitored by 3D AE tomography. AE counts, AE source locations and 3D tomographic images of locally varying velocity distributions were analyzed along with stress and strain measurements. Experimental results revealed two distinct failure processes between Brazilian tests and uniaxial compression tests indicated by differences in AE counts, source locations and the temporal variation of velocity. Furthermore, the development of micro-cracks showed by the results correlated well with theoretical analysis and experimental observations. Additionally, stress patterns, failure modes and final failure planes were indicated by AE locations and velocity tomography. Three-dimensional velocity tomographic images indicated the anisotropy of samples caused by stresses as well. These results confirm the usefulness of AE tomography as a method to monitor stress induced failure and the potential of AE tomography for delineating stress conditions and predicting rock failure.

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