Dynamic Indirect Tensile Strength of Sandstone Under Different Loading Rates

Gong, Fengqiang; Zhao, Gao‐Feng

doi:10.1007/s00603-013-0503-7

Cited by 95 publications

(33 citation statements)

References 23 publications

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“…e loading process is displacementcontrolled, and the load speed is 0.002 mm/s. e staticdynamic load test is conducted with a modified SHPB testing system, as shown in Figure 1 [14,15]. is system uses halfsine stress wave loading.…”

Section: Testing Equipmentmentioning

confidence: 99%

Analysis of the Dynamic Impact Mechanical Characteristics of Prestressed Saturated Fractured Coal and Rock

Wen

Zhang

et al. 2019

Advances in Civil Engineering

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e natural and water-saturated states of coal samples under static and static-dynamic loads were tested using the Split-Hopkinson pressure bar (SHPB) method and RMT-150 system, respectively. e differences in the strength reduction coefficient and elastic modulus reduction coefficient of water-saturated coal samples under static and static-dynamic loads were discussed. e experimental results for coal were compared with the corresponding characteristics of typical sandstone samples under static and static-dynamic loads. Furthermore, a fracture model of a hydrous wing branch fracture under static-dynamic loading was established based on the theory of fracture damage mechanics. e difference in dynamic strength between coal and sandstone samples for both the natural state and water-saturated state was analyzed. On this basis, the effect of water on the fracture surface of coal and the tensile strength and shear strength of the branch fracture surface were fully considered. In addition, criteria of the branch fracture surface for crack initiation and crack arrest were also established. Finally, the phenomenon of increasing elastic modulus in saturated coal samples was explained with this criterion.

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Section: Testing Equipmentmentioning

confidence: 99%

Analysis of the Dynamic Impact Mechanical Characteristics of Prestressed Saturated Fractured Coal and Rock

Wen

Zhang

et al. 2019

Advances in Civil Engineering

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“…In experimental research of rock materials, the direct tensile test is considered the most effective method for determining rock tensile strength [2][3][4][5]. However, due to the difficulty of specimen processing and pure one-dimensional direct tensile loading, the Brazilian disc test was introduced and used widely to determine the indirect tensile strength of rock or rock-like materials [3,4,6,7], which has been accepted by many researchers [8][9][10][11][12][13] or test standards [14][15][16] because of its simplicity and ease of operation. In Brazilian disc tests, three sets of loading methods, including the strip loading method, the circular arc loading method, and the plate loading method, were usually adopted to measure the indirect tensile strength of rock materials [17].…”

Section: Introductionmentioning

confidence: 99%

Loading Rate Effect of Rock Material with the Direct Tensile and Three Brazilian Disc Tests

Gong

Wang

2019

Advances in Civil Engineering

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A series of experimental tests were conducted to investigate the effects of loading rate on the tensile strength of sandstone by using four test methods, including a direct tensile method and three typical Brazilian disc methods (plate loading, circular arc loading, and strip loading). e loading rates used in these tests varied from 10 −2 MPa/s to 10 0 MPa/s. e results show that the rate effects are clear for these test methods, and the tensile strength of sandstone will increase linearly with the logarithm of the loading rate. At the same loading rate, it is found that the tensile strengths of the sandstone specimens under plate loading and arc loading are relatively similar and are much greater than the direct tensile strength, while the tensile strength under strip loading is less than the direct strength. A comprehensive comparison suggested that the strip loading method can be adopted for the Brazilian disc test, while the obtained strength should be modified with a coefficient of 1.37 to obtain the direct tensile strength.

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“…However, this equation represents a specific range of strain rates and for particular materials and so may be not suited to describe the essential features of strain rate dependence for a broad range of strain rates and different materials. Moreover, prominent strength fluctuations have been observed in rock material for the range of strain rates from 10 −3 to 10 −1 s −1 [ Gong and Zhao , ].…”

Section: Results Analysis and Discussionmentioning

confidence: 99%

Failure mechanisms in coal: Dependence on strain rate and microstructure

et al. 2014

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The brittle coal failure behavior under various axial strain rates from 10 À3 to 10 À2 s À1 is experimentally and numerically studied. The numerical microscale finite difference model is built on the accurate X-ray microcomputed tomography images, which provides a ground-breaking and bottom-up approach to investigate the effects of microstructure on coal failure under various strain rates. Experimentally, prior to loading, the coal sample is scanned, and the three-dimensional coal structure model is constructed. The microheterogeneous structures are incorporated in the model, which facilitates the deformation and failure mechanism analysis under different loading conditions. The results reveal that the microheterogeneous structures significantly affect the evolution of stress concentrations and deformation behaviors in the sample. The coal tends to fail in the shear mode before the peak strength, since the shear zone is created with high displacements. However, tensile failure ultimately controls the failure process after the peak strength. Notably, the strain rate dependence of coal strength is observed, and an empirical relationship is proposed to describe the dynamic strength of the coal under various loading strain rates. Importantly, the coal strengthens with an increase in strain rate. For brittle material, such as coal, the strength and failure mechanism are strain rate and microstructure dependent. The strain rate-dependent coal strength index (n) is found to be a dynamic parameter in the range of strain rate from 10 À3 to 10 À2 s À1, and this finding may extend the concept of strain rate dependence over a broader range of loading conditions.

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Dynamic Indirect Tensile Strength of Sandstone Under Different Loading Rates

Cited by 95 publications

References 23 publications

Analysis of the Dynamic Impact Mechanical Characteristics of Prestressed Saturated Fractured Coal and Rock

Analysis of the Dynamic Impact Mechanical Characteristics of Prestressed Saturated Fractured Coal and Rock

Loading Rate Effect of Rock Material with the Direct Tensile and Three Brazilian Disc Tests

Failure mechanisms in coal: Dependence on strain rate and microstructure

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