Correlating acoustic emission sources with damaged zones during direct shear test of rock joints

2012 ◽  
Vol 49 (6) ◽  
pp. 710-718 ◽  
Author(s):  
Z.A. Moradian ◽  
G. Ballivy ◽  
P. Rivard
Keyword(s):  
Acoustic Emission ◽  
Acoustic Waves ◽  
Normal Load ◽  
Rock Joint ◽  
Load Condition ◽  
Rock Joints ◽  
Joint Surfaces ◽  
Rock Cores ◽  
Asperity Degradation ◽  
Constant Normal Load Condition

Applicability of acoustic emission (AE) for localizing asperity damaged zones and damage intensity in joint surfaces was evaluated in this paper. With this attempt, rock joint samples obtained from tension splitting of the rock cores were tested under constant normal load condition. The locations of the AE sources were determined from propagation velocity of acoustic waves and by measuring the transferring time from event source to AE sensor. These sources correspond to asperity damaged zones. The AE signals generated from asperity degradation of joint surfaces were detected during shear testing. The energy of the generated signals was also measured to assess the intensity of the asperity failure. The results of this study showed that the AE method has a good capability in localizing the asperities’ failure points and the intensity (energy) of the asperities’ failure.

Rock joint modeling using a visco-plastic multilaminate model at constant normal load condition

2006 ◽  
Vol 24 (5) ◽  
pp. 1449-1468 ◽  
Author(s):  
Reza Mahin Roosta ◽  
Mohammad Hossein Sadaghiani ◽  
Ali Pak ◽  
Yaser Saleh
Keyword(s):  
Normal Load ◽  
Rock Joint ◽  
Load Condition ◽  
Joint Modeling ◽  
Constant Normal Load ◽  
Constant Normal Load Condition

scholarly journals Characterization of rock joint surface anisotropy considering the contribution ratios of undulations in different directions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Man Huang ◽  
Chenjie Hong ◽  
Chengrong Ma ◽  
Zhanyou Luo ◽  
Shigui Du
Keyword(s):  
Rock Joint ◽  
Weight Ratio ◽  
Rock Joints ◽  
Joint Surface ◽  
Orthogonal Direction ◽  
Natural Rock ◽  
Joint Surfaces ◽  
The Common ◽  
Joint Morphology

Abstract Anisotropy in rock joint is strongly dependent on undulating surface morphology. Recent research of the morphology showed the parameter can express the different types of anisotropic characteristics of the joint surface separately. This report aims to analyze the common characteristic of the anisotropic distribution and exhibit the anisotropic variation trend. The joint morphology function consists of two morphology functions of regular plane in orthogonal directions, and the anisotropic variation determined by the contribution ratios of the two morphology. The roughness weight ratio in orthogonal direction of joint surface is used as an index to describe the anisotropic variation behavior, which proposes the anisotropic variation coefficient (AVC). On this basis, it is divided into 5 levels from strong anisotropic to isotropic. According to the assumption of anisotropic arc distribution, the anisotropic analytic function is derived and the agreement between the deduced curves and measured data therefore suggests the possibility of defining the morphology anisotropy through the index AVC. Finally, we verify the characteristic of three natural rock joints, and prove the proposed function can reflect the anisotropic distribution trend. The new index can be used to describe the anisotropic variation behaviour of rock joint surfaces.

The influence of ultrasound signal parameters on sonoluminescence light intensity

2013 ◽  
Vol 62 (4) ◽  
pp. 605-612
Author(s):  
Marek Szmechta ◽  
Tomasz Boczar ◽  
Dariusz Zmarzły
Keyword(s):  
Acoustic Emission ◽  
Acoustic Waves ◽  
Power Transformer ◽  
Electrical Power ◽  
Partial Discharges ◽  
Research Project ◽  
Insulation Systems ◽  
Secondary Phenomenon ◽  
New Research ◽  
The Relationship

Abstract Topics of this article concern the study of the fundamental nature of the sonoluminescence phenomenon occurring in liquids. At the Institute of Electrical Power Engineering at Opole University of Technology the interest in that phenomenon known as secondary phenomenon of cavitation caused by ultrasound became the genesis of a research project concerning acoustic cavitation in mineral insulation oils in which a number of additional experiments performed in the laboratory aimed to determine the influence of a number of acoustic parameters on the process of the studied phenomenona. The main purpose of scientific research subject undertaken was to determine the relationship between the generation of partial discharges in high-voltage power transformer insulation systems, the issue of gas bubbles in transformer oils and the generated acoustic emission signals. It should be noted that currently in the standard approach, the phenomenon of generation of acoustic waves accompanying the occurrence of partial discharges is generally treated as a secondary phenomenon, but it can also be a source of many other related phenomena. Based on our review of the literature data on those referred subjects taken, it must be noted, that this problem has not been clearly resolved, and the description of the relationship between these phenomena is still an open question. This study doesn’t prove all in line with the objective of the study, but can be an inspiration for new research project in the future in this topic. Solution of this problem could be a step forward in the diagnostics of insulation systems for electrical power devices based on non-invasive acoustic emission method.

Evaluation of Fatigue Crack Growth Characteristics on Stainless Steel SS 316 LN Using Acoustic Emission Technique

2020 ◽  
Author(s):  
Raghu V. Prakash ◽  
Manuel Thomas
Keyword(s):  
Stainless Steel ◽  
Acoustic Emission ◽  
Fatigue Crack ◽  
Elevated Temperature ◽  
Fatigue Crack Growth ◽  
Crack Growth ◽  
Acoustic Waves ◽  
Crack Advance ◽  
Cumulative Energy ◽  
Good Correspondence

Abstract Results of online acoustic emission (AE) monitoring during fatigue crack growth rate (FCGR) experiments on a stainless steel SS 316 LN are presented in this paper. Two specimen geometries — viz., standard compact tension (C(T)) specimens as well as side-grooved C(T) specimens were considered for experiments at ambient temperature and at 600°C (873K). There is a good correspondence between crack length increment and the increase in AE cumulative count and cumulative energy during the experiments. The side grove introduced on the thickness direction of the test specimen constrains the plastic zone ahead of the crack tip, thereby enforcing plane strain conditions at the crack. Reduced AE activity at initial stages of crack growth was observed for side grooved samples. The transition to Stage-II crack growth was observed using acoustic emission (AE) technique which otherwise was not visible from the fatigue crack growth plot. The work further attempts to correlate the AE parameters obtained during elevated temperature (873K) fatigue crack growth in stainless steel. For the purpose of acquiring AE signals outside the heated zone, a waveguide was used to transmit the acoustic waves from the specimen at high temperature. A correlation between crack advance and AE parameters was obtained from the elevated temperature tests.

scholarly journals Experimental Study on Hydromechanical Behavior of an Artificial Rock Joint with Controlled Roughness

2019 ◽  
Vol 11 (4) ◽  
pp. 1014
Author(s):  
Seungbeom Choi ◽  
Byungkyu Jeon ◽  
Sudeuk Lee ◽  
Seokwon Jeon
Keyword(s):  
Rock Mass ◽  
Rock Joint ◽  
Great Influence ◽  
Rock Joints ◽  
In Situ Tests ◽  
Joint Roughness ◽  
Artificial Rock ◽  
Geometric Conditions ◽  
Bedding Planes ◽  
Hydraulic Aperture

Rock mass contains various discontinuities, such as faults, joints, and bedding planes. Among them, a joint is one of the most frequently encountered discontinuities in rock engineering applications. Generally, a joint exerts great influence on the mechanical and hydraulic behavior of rock mass, since it acts as a weak plane and as a fluid path in the rock mass. Therefore, an accurate understanding on joint characteristics is important in many projects. In-situ tests on joints are sometimes consumptive in terms of time and expenses so that the features are investigated by laboratory tests, providing fundamental properties for rock mass analyses. Although the behavior of a joint is affected by both mechanical and geometric conditions, the latter are often limited, since quantitative control on the conditions is quite complicated. In this study, artificial rock joints with various geometric conditions, i.e., joint roughness, were prepared in a quantitative manner and the hydromechanical characteristics were investigated by several laboratory experiments. Based on the results, a prediction model for hydraulic aperture was proposed in the form of ( e h / e m ) 3 = exp ( − 0.0462 c ) × ( 0.8864 ) J R C , which was a function of the mechanical aperture, joint roughness, and contact area. Relatively good agreement between the experimental results and predicted value indicated that the model is capable of estimating the hydraulic aperture properly.

scholarly journals A New Representative Sampling Method for Series Size Rock Joint Surfaces

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Man Huang ◽  
Chenjie Hong ◽  
Chengrong Ma ◽  
Zhanyou Luo ◽  
Shigui Du ◽  
...  
Keyword(s):  
Sampling Method ◽  
Rock Joint ◽  
Representative Sampling ◽  
Joint Surfaces

Time-dependent behavior of rock joints considering asperity degradation

2019 ◽  
Vol 121 ◽  
pp. 1-9 ◽  
Author(s):  
Qingzhao Zhang ◽  
Chuangzhou Wu ◽  
Xunchang Fei ◽  
Bo An Jang ◽  
Dongqiao Liu
Keyword(s):  
Rock Joints ◽  
Time Dependent ◽  
Dependent Behavior ◽  
Asperity Degradation

Asperity degradation characteristics of soft rock-like fractures under shearing based on acoustic emission monitoring

2020 ◽  
Vol 266 ◽  
pp. 105392 ◽  
Author(s):  
Fanzhen Meng ◽  
Louis Ngai Yuen Wong ◽  
Hui Zhou ◽  
Zaiquan Wang ◽  
Liming Zhang
Keyword(s):  
Acoustic Emission ◽  
Soft Rock ◽  
Acoustic Emission Monitoring ◽  
Emission Monitoring ◽  
Asperity Degradation

scholarly journals Optimized Analysis Method for Evaluating the Shear Strength Parameters of Rock Joint Surfaces

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Yao Xiao ◽  
Huafeng Deng ◽  
Jingcheng Fang ◽  
Hengbin Zhang ◽  
Jianlin Li
Keyword(s):  
Shear Strength ◽  
Empirical Equation ◽  
Mechanical Test ◽  
Rock Joint ◽  
Test Results ◽  
Analysis Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Joint Surfaces ◽  
Multiple Sample

The results obtained from the mechanical test of rock samples inevitably suffer dispersion owing to discrepancies between test specimens. In view of these deficiencies, the present study proposes a method based on the empirical equation of shear strength developed by Barton to determine the shear strength parameters of joint surfaces using a single test specimen. This approach is then applied to optimize the analysis of multiple specimens. An analysis of experimental results verifies that the shear strength parameters of joint surfaces obtained by the proposed method can more accurately reflect the shear mechanics of multiple specimens than conventional multiple sample analyses; meanwhile, the results are reasonable and reliable. More importantly, the optimized method ensures the shear strength parameters are no longer affected by the sequence of specimens employed during shear test. The optimized analysis method eliminates the effect of differences between specimens and the influence of subjective factors on test results and therefore provides more realistic evaluations of shear strength parameters.

Verification of UDEC Modeling 1-D Wave Propagation in Rocks

2011 ◽  
Vol 90-93 ◽  
pp. 1998-2001
Author(s):  
Wei Dong Lei ◽  
Xue Feng He ◽  
Rui Chen
Keyword(s):  
Wave Propagation ◽  
Analytical Solution ◽  
Transmission Coefficient ◽  
Method Of Characteristics ◽  
Rock Joint ◽  
Rock Joints ◽  
Dynamic Problems ◽  
The Method Of Characteristics ◽  
Elastic Rock ◽  
D Wave

Three cases for 1-D wave propagation in ideal elastic rock, through single rock joint and multiple parallel rock joints are used to verify 1-D wave propagation in rocks. For the case for 1-D wave propagation through single rock joint, the magnitude of transmission coefficient obtained from UDEC results is compared with that obtained from the analytical solution. For 1-D wave propagation through multiple parallel joints, the magnitude of transmission coefficient obtained from UDEC results is compared with that obtained from the method of characteristics. For all these cases, UDEC results agree well with results from the analytical solutions and the method of characteristics. From these verification studies, it can be concluded that UDEC is capable of modeling 1-D dynamic problems in rocks.

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