Rate effect on mechanical properties of hydraulic concrete flexural-tensile specimens under low loading rates using acoustic emission technique

Su, Huaizhi; Hu, Jiang; Jianjie, Tong; Wen, Zhiping

doi:10.1016/j.ultras.2012.02.011

Cited by 30 publications

(15 citation statements)

References 21 publications

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“…In addition, two loading modes for the uniaxial compression test were present in this MTS machine, which are the load-controlled mode [ 22 ] and displacement-controlled mode [ 23 ]. The specimen might show a relatively short breakage duration under the load-controlled mode [ 24 ]. Thus, fewer AE events can be captured, so we adopted the displacement-controlled mode to stably proceed to the uniaxial compression.…”

Section: Methodsmentioning

confidence: 99%

Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions

et al. 2015

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Underground rock masses have shown a general trend of natural balance over billions of years of ground movement. Nonetheless, man-made underground constructions disturb this balance and cause rock stability failure. Fractured rock masses are frequently encountered in underground constructions, and this study aims to restore the strength of rock masses that have experienced considerable fracturing under uniaxial compression. Coal and sandstone from a deep-buried coal mine were chosen as experimental subjects; they were crushed by uniaxial compression and then carefully restored by a chemical adhesive called MEYCO 364 with an innovative self-made device. Finally, the restored specimens were crushed once again by uniaxial compression. Axial stress, axial strain, circumferential strain, and volumetric strain data for the entire process were fully captured and are discussed here. An acoustic emission (AE) testing system was adopted to cooperate with the uniaxial compression system to provide better definitions for crack closure thresholds, crack initiation thresholds, crack damage thresholds, and three-dimensional damage source locations in intact and restored specimens. Several remarkable findings were obtained. The restoration effects of coal are considerably better than those of sandstone because the strength recovery coefficient of the former is 1.20, whereas that of the latter is 0.33, which indicates that MEYCO 364 is particularly valid for fractured rocks whose initial intact peak stress is less than that of MEYCO 364. Secondary cracked traces of restored sandstone almost follow the cracked traces of the initial intact sandstone, and the final failure is mainly caused by decoupling between the adhesive and the rock mass. However, cracked traces of restored coal only partially follow the traces of intact coal, with the final failure of the restored coal being caused by both bonding interface decoupling and self-breakage in coal. Three-dimensional damage source locations manifest such that AE events are highly correlated with a strength recovery coefficient; the AE events show a decreasing tendency when the coefficient is larger than 1, and vice versa. This study provides a feasible scheme for the reinforcement of fractured rock masses in underground constructions and reveals an internal mechanism of the crushing process for restored rock masses, which has certain instructive significance.

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Section: Methodsmentioning

confidence: 99%

Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions

et al. 2015

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“…Other scholars also studied the static fracturing of rock and concrete under the effect of SCDAs and derived some important conclusions [18][19][20]. As for research on the AE characteristics associated with the static fracturing process in concrete, most of the existing studies have focused on AE in concrete under loading conditions [21][22][23][24][25][26][27]. Little research has been conducted on AE in concrete during static fracturing.…”

Section: Introductionmentioning

confidence: 99%

Acoustic Emission Characteristics of Normal and Layered Concrete Blocks during Dilating/Static Fracture

Zhang

2020

Advances in Materials Science and Engineering

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Static fracturing technology is one of the most effective methods for localized breaking of rock and concrete. Layered concrete and rock structures are commonly seen in engineering applications such as breaking of concrete buildings, stone cutting, and excavation of rock in underground spaces. Therefore, it is essential to study the static fracturing characteristics of layered concrete to ensure the safety of engineering construction processes. In this paper, using acoustic emission (AE) technology and surface displacement monitoring, the deformation and fracturing of ordinary-strength concrete, concrete with a soft interlayer, and layered concrete (with strength decreasing successively by layer) were studied under the effect of a static (or soundless) cracking agent (SCA). The experimental results indicated that (1) AE activity of the two layered concrete test blocks during static fracturing showed a gradually increasing trend, while that of the ordinary-strength concrete tended to first increase and then decrease; (2) for the concrete test block with a soft interlayer sandwiched by high-strength layers, the AE events reached a maximum in the transfer of expansion pressure stage, which accounted for 47.11% of the total value in static cracking; the macroscopic damage to layered concrete test blocks comprising multiple interlaid layers with different strengths mainly occurred in the fracturing stage, during which the AE events and AE energy accounted for 76.22% and 66.94%, respectively, of those in the whole static fracturing process; and (3) the duration of static fracturing prolonged with the increase of the overall strength of the concrete test blocks. The results provide a useful experimental reference for the application of static fracturing technology in the breaking of layered concrete and rock.

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“…[18][19][20] AE is a kind of emission stress wave in a solid material. The AE has been generally used in engineering applications for internal defects, [21,22] crack initiation, [23,24] fatigue life, [25,26] fracture location, [27,28] evaluation of the failure mechanisms, and process and damage characterization.…”

Section: Introductionmentioning

confidence: 99%

“…Nowadays the acoustic emission (AE), discovered by Kishinoue in 1933, has been widely applied in nondestructive mechanical testing of high-temperature and high-pressure vessels, bridge, ship, aerospace, etc. [18][19][20] AE is a kind of emission stress wave in a solid material. The AE has been generally used in engineering applications for internal defects, [21,22] crack initiation, [23,24] fatigue life, [25,26] fracture location, [27,28] evaluation of the failure mechanisms, and process and damage characterization.…”

Section: Introductionmentioning

confidence: 99%

Failure Mechanism of Brass with Three V‐Notches Characterized by Acoustic Emission in In Situ Three‐Point Bending Tests

et al. 2016

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The purpose of this study is to characterize the V pre-notched specimens with different relative depth ratio and the relative distance ratio by the AE signals in in situ three-point bending tests. Simultaneously, during the bending process, the V pre-notched specimen is in situ monitored by the opto-digital microscope. In order to analyze the depth of V-notch and the distance between the side V-notches and the middle V-notch effect on the specimens, a finite element analysis model is built by ABAQUS. Combining the in situ images, the AE signals and the finite element analysis (FEA) results, it is found that the experiment results are consistent with the FEA results. It is demonstrated that the amplitude of AE signals can effectively characterize the crack initiation, crack growth, and crack fast instability fracture.

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Rate effect on mechanical properties of hydraulic concrete flexural-tensile specimens under low loading rates using acoustic emission technique

Cited by 30 publications

References 21 publications

Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions

Strength Restoration of Cracked Sandstone and Coal under a Uniaxial Compression Test and Correlated Damage Source Location Based on Acoustic Emissions

Acoustic Emission Characteristics of Normal and Layered Concrete Blocks during Dilating/Static Fracture

Failure Mechanism of Brass with Three V‐Notches Characterized by Acoustic Emission in In Situ Three‐Point Bending Tests

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