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.

Failure Process of Rock Sample Observed by AE Source Locating Technique under Uniaxial Compression

2006 ◽  
Vol 324-325 ◽  
pp. 567-570
Author(s):  
Yuan Hui Li ◽  
Rui Fu Yuan ◽  
Xing Dong Zhao
Keyword(s):  
Uniaxial Compression ◽  
High Speed ◽  
Failure Process ◽  
Compression Tests ◽  
Temporal And Spatial Distribution ◽  
Primary Stage ◽  
Brewing Process ◽  
Ae Signal ◽  
Failure Location ◽  
Low Amplitude

A series of uniaxial-compression tests were conducted on some representative brittle rock specimens, such as granite, marble and dolerite. A multi-channel, high-speed AE signal acquiring and analyzing system was employed to acquire and record the characteristics of AE events and demonstrate the temporal and spatial distribution of these events during the rupture-brewing process. The test result showed that in the primary stage, many low amplitude AE events were developed rapidly and distributed randomly throughout the entire specimens. In the second stage, the number of AE increased much slower than that in the first stage, while the amplitude of most AE events became greater. Contrarily to the primary stage, AE events clustered in the middle area of the specimen and distributed vertically conformed to the orientation of compression. The most distinct characteristic of this stage was a vacant gap formed approximately in the central part of the specimen. In the last stage, the number of AE events increased sharply and their magnitude increased accordingly. The final failure location coincidently inhabited the aforementioned gap. The main conclusion is that most macrocracks are developed from the surrounding microcracks existed earlier and their positions occupy the earlier formed gaps, and the AE activity usually becomes quite acute before the main rupture occurs.

scholarly journals Mechanical Properties and Acoustic Emission Characteristics of Karst Limestone under Uniaxial Compression

2018 ◽  
Vol 2018 ◽  
pp. 1-14 ◽  
Author(s):  
Jianxun Chen ◽  
Qingsong Wang ◽  
Jiaqi Guo ◽  
Yanbin Luo ◽  
Yao Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Water Content ◽  
Uniaxial Compression ◽  
Wave Velocity ◽  
Brittle Failure ◽  
Shear Failure ◽  
Testing Machine ◽  
Natural State ◽  
Saturated State

Firstly, I-RPT ultrasonic detector was used to test the wave velocity of karst limestone with different initial microstructure and water content. Then, RMT-150B rock testing machine and DS2-16B acoustic emission system were used to test the acoustic emission (AE) under uniaxial compression. Mechanical properties and AE characteristics were obtained during rock failure. The detailed relationship between stress-strain and AE characteristics was studied in this paper. Research results indicated the following: (1) For samples with many primary fissures and defects, wave velocity in dry state was larger than that in its natural state. From natural state to saturated state, the wave velocity tended to increase. For samples with good integrity, wave velocity increased with increasing of water content. (2) In the dry state, the samples presented tension failure. In saturated state, the samples presented tension-shear failure. For samples with cracks and good integrity, samples showed brittle failure. For samples with many corrosion pores which showed ductile damage under natural and saturated state, the spalling phenomenon was enhanced under saturated state. (3) With increasing of water content, the peak stress and AE peak reduced dramatically. In brittle failure, AE peak could be considered a sign of failure. In ductile failure, AE activity decreased gradually with the decrease of stress. (4) The mechanical properties and AE characteristics corresponding to four main fracture propagation types were also discussed.

Acoustic Emission Characteristics of Rock Failure under Uniaxial Loading

2011 ◽  
Vol 378-379 ◽  
pp. 43-46 ◽  
Author(s):  
Tao Xie ◽  
Qing Hui Jiang ◽  
Rui Chen ◽  
Wei Zhang
Keyword(s):  
Acoustic Emission ◽  
Failure Modes ◽  
Mechanical Performance ◽  
Progressive Failure ◽  
Failure Process ◽  
Testing Machine ◽  
Rock Failure ◽  
Rock Failure Process ◽  
State Variation ◽  
Acoustic Emission Test

With RMT-150C rock testing machine and AEWIN E1.86 DISP acoustic emission system applied, the acoustic emission test was accomplished with two kinds of rock samples including marble and granite under uniaxial compression. Cyclic loading and continuous loading were used through the experiment, and the mechanical performance and acoustic emission (AE) characteristics were obtained during the process of rock progressive failure. Details related to the relationship between amount of AE and stress-strain was given in this paper. A comparison between marble and granite was made as well following the general AE law, on the basis of which, the failure mechanism of rock mass was investigated. Finally, some conclusions can be summarized as follows:(1) AE activity features are different with stress state variation in rock failure process;(2) loading patterns make a direct impact on the failure process thereby affecting AE activities;(3)AE activities are various basing on the different types of rocks, structures and failure modes.

Experimental Research on Acoustic Emission of Granite under Uniaxial Compression and Splitting Tensile

2012 ◽  
Vol 232 ◽  
pp. 24-27
Author(s):  
Zong Zhan Li ◽  
Jun Lin Tao ◽  
Yi Li
Keyword(s):  
Compressive Strength ◽  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Uniaxial Compressive Strength ◽  
Loading Rate ◽  
Testing Machine ◽  
Peak Stress ◽  
Uniaxial Compression Test ◽  
Peak Strain ◽  
Ae Energy

This paper makes the acoustic emission of granite under uniaxial compression and splitting tensile test by electro-hydraulic testing machine and AE .We studied the relationship of uniaxial compressive strength and splitting tensile strength with the loading rate and AE characteristics of granite .The results show that uniaxial compressive strength and peak strain raise with loading rate, the AE energy gradually increases and get maximum in the 30% of the peak stress in the process of uniaxial compression test, and in the splitting tensile AE energy generates in the initial loading and gets maximum when the granite brittle fracture.

scholarly journals Acoustic Emission Multi-Parameter Analysis of Dry and Saturated Sandstone with Cracks under Uniaxial Compression

Energies ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1959 ◽  
Author(s):  
Hongru Li ◽  
Rongxi Shen ◽  
Dexing Li ◽  
Haishan Jia ◽  
Taixun Li ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Uniaxial Compression ◽  
Fractured Rock ◽  
Rock Fracture ◽  
Failure Process ◽  
Parameter Analysis ◽  
Small Scale ◽  
Rock Interaction ◽  
Secondary Cracks ◽  
Ae Signals

In order to study the mechanics and acoustic emission (AE) characteristics of fractured rock under water-rock interaction, dried and saturated sandstone samples with prefabricated double parallel cracks were prepared. Then, uniaxial compression experiments were performed to obtain their AE signals and crack propagation images. The results show that water reduces the strength and fracture toughness of fractured sandstone and enhances plasticity. After saturation, the samples start to crack earlier; the cracks grow slowly; the failure mode is transformed from shear failure along the prefabricated cracks to combined shear and tensile failure; more secondary cracks are produced. The saturated samples release less elastic energy and weaker AE signals in the whole failure process. However, their AE precursor information is more obvious and advanced, and their AE sources are more widely distributed. Compared with dry specimens, the AE frequencies of saturated specimens in the early stage of loading are distributed in a lower frequency domain. Besides, the saturated samples release less complex AE signals which are dominated by small-scale signals with weaker multi-fractal characteristics. After discussion and analysis, it is pointed out that this may be because water makes rock prone to inter-granular fracture rather than trans-granular fracture. The water lubrication also may reduce the amplitude of middle-frequency band signals produced by the friction on the fracture surface. Multi-fractal parameters can provide more abundant precursory information for rock fracture. This is of great significance to the stability of water-bearing fractured rock mass and its monitoring, and is conducive to the safe exploitation of deep energy.

scholarly journals Acoustic Emission Analysis of Corroded Reinforced Concrete Columns under Compressive Loading

Sensors ◽  
2020 ◽  
Vol 20 (8) ◽  
pp. 2412 ◽  
Author(s):  
Qiang Li ◽  
Xianyu Jin ◽  
Dan Wu ◽  
Hailong Ye
Keyword(s):  
Acoustic Emission ◽  
Reinforced Concrete ◽  
Failure Process ◽  
Compressive Loading ◽  
Reinforcement Corrosion ◽  
Emission Analysis ◽  
Rc Columns ◽  
Damage And Failure ◽  
Highly Active ◽  
Initial Stage

In this work, the failure process of non-corroded and corroded reinforced concrete (RC) columns under eccentric compressive loading is studied using the acoustic emission (AE) technique. The results show that reinforcement corrosion considerably affects the mechanical failure process of RC columns. The corrosion of reinforcement in RC columns leads to highly active AE signals at the initial stage of loading, in comparison to the non-corroded counterparts. Also, a continuous AE hit pattern with a higher number of cumulative hits is observed for corroded RC columns. The spatial distribution and evolution of AE events indicate that the reinforcement corrosion noticeably accelerates the initiation and propagation of cracking in the RC columns during compressive loading. The AE characteristics of corroded RC columns are in agreement with the macroscopic failure behaviors observed during the damage and failure process. A damage evolution model of corroded RC columns based on the AE parameters is proposed.

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.

Damage Evolution Analysis of Calcareous Mudstone with Different Water Content under Uniaxial Compression

2010 ◽  
Vol 168-170 ◽  
pp. 1388-1395
Author(s):  
Ming Ji ◽  
Nong Zhang ◽  
Feng Gao
Keyword(s):  
Acoustic Emission ◽  
Water Content ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Testing Machine ◽  
Strain Curve ◽  
Peak Stress ◽  
Damage Evolution Equation ◽  
Emission Activity ◽  
Hydraulic Servo

Uniaxial compression and acoustic emission experiments of calcareous mudstone with different water content were carried out by using microcomputer controlled electro-hydraulic servo compression testing machine control system of YAW series equipped by coal-rock acoustic and electric data acquisition system of CTA-1-type. Mchanical properties and acoustic emission law of calcareous mudstone were studied. It is concluded from experiment result that rock’s elastic modulus and compressive strength both decrease with increase water content but peak stress shows the opposite trend. It is also found that calcareous mudstone is brittleness with low water content but when water content reaches saturation, calcareous mudstone presents plastic features. Acoustic emission curve fits well with stress-strain curve: acoustic emission activity begins intensifying when stress reaches 70% of peak stress, correspondingly, acoustic emission is up to maximum at peak stress. Based on Weibull hypothesis and acoustic emission experiment, damage law of water bearing calcareous mudstone is researched and damage evolution equation with time variable is advanced.

Mechanical behavior and damage mechanism of loaded coal and rock

2017 ◽  
Vol 14 (3) ◽  
pp. 200-207 ◽  
Author(s):  
Feng Luo ◽  
Guodong Li ◽  
Hao Zhang
Keyword(s):  
Mechanical Behavior ◽  
Uniaxial Compression ◽  
Axial Compression ◽  
Compression Test ◽  
Growth Stage ◽  
Shear Failure ◽  
Failure Process ◽  
Damage Mechanism ◽  
Uniaxial Compression Test ◽  
Content Type

Purpose The purpose of this paper is to obtain the mechanical behavior and damage mechanism of the coal and rock near the stope under the stress state and stress paths of the surrounding rock with the dynamic mining. Design/methodology/approach Through the three-axial compression test and the uniaxial compression test by meso experiment device, the mechanical behavior and fracture evolution process of coal and rock were studied, and the acoustic emission (AE) characteristics under uniaxial compression of the coal and rock were contrasted. Findings Under the three-axial compression, the strength of coal and rock enhance significantly by confining pressure. The volume of outburst coal shows obvious stages: compression is followed by expansion. The coal first appear to undergo compaction under vertical stress due to volume decrease, but with the development of micro- and macro-cracks, the specimens appeared to expand; under the uniaxial compression, through the comparison of stress–strain relationship and the crack propagation process, stress drop and fracture of coal have obvious correlation. The destruction of coal was gradual due to the slow and steady accumulation of internal damage. Due to the influence of the end effect, the specimens show the “conjugate double shear failure”. The failure process of the coal and rock and the characteristics of the AEs have a corresponding relationship: the failure causes a large number of AE events. Before the events peak, there was an initial stage, calm growth stage and explosive growth stage. There were some differences between the rock and coal in the characteristics of the AE. Originality/value These research studies are conducted to provide guidance on the basis of mine disaster prevention and control.

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.

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