Experiment on the Failure Process of Jointed Rock Specimen Under Compression and Numerical Test

2018 ◽  
pp. 158-165
Author(s):  
Hao Zhou ◽  
Yang Song ◽  
Qimin Wang ◽  
Weishen Zhu ◽  
Yanqing Men
Keyword(s):  
Rock Specimen ◽  
Failure Process ◽  
Numerical Test ◽  
Jointed Rock

Numerical Simulation of the Crack Propagation Processes in Rocks with Double Joints

2011 ◽  
Vol 90-93 ◽  
pp. 559-564 ◽  
Author(s):  
Jin Wei Fu ◽  
Wei Shen Zhu ◽  
Li Ge Wang ◽  
Xiang Gang Wang
Keyword(s):  
Numerical Simulation ◽  
Rock Mass ◽  
Crack Initiation ◽  
Rock Specimen ◽  
Failure Process ◽  
Jointed Rock ◽  
Two Dimensional ◽  
Analysis Software ◽  
Strength And Stiffness ◽  
The Stability

Engineering rock mass is commonly a brittle medium containing lots of joints or fissures. Under the stress redistribution in construction，the crack initiation，propagation，and coalescence may cause the strength and stiffness degradation of such medium. And these have an important impact on the stability of rock mass. By employing the analysis software of FLAC3D and improving the constitutive relation, the failure process of the double-cracked rock specimen under uniaxial and two-dimensional compression are simulated and studied. The numerical results match well with the testing results obtained by former scholars. The strength envelope of the jointed rock is obtained as well, and it is applied to analyzing the stability of a slope project.

Effect of Materials Characteristics on Average Crack Spacing of Reinforced Concrete Specimen

2011 ◽  
Vol 704-705 ◽  
pp. 817-822
Author(s):  
Juan Xia Zhang ◽  
Xian Zhang Guo ◽  
Zheng Zhao Liang ◽  
Ya Fang Zhang
Keyword(s):  
Reinforced Concrete ◽  
Process Analysis ◽  
Concrete Strength ◽  
Failure Process ◽  
Numerical Test ◽  
Peak Load ◽  
Crack Spacing ◽  
Fracture Spacing ◽  
Average Crack ◽  
Initial Peak

The goal of the present work is to investigate the influence of concrete on failure mode and stress distribution of the reinforced concrete specimens under axial tension by using a numerical test code named Realistic Failure Process Analysis. It can be found that, the periodically distributed fracture spacing phenomenon and tension stiffening phenomenon exist in the failure process of the reinforced concrete structure. Besides, the effect of concrete characteristics on the mechanical behavior and crack spacing of reinforced concrete was also studied in three samples with different concrete strength. The concrete strength value is considered to be an important factor not only to significantly influence the average crack spacing but also to influence the initial peak load of the specimen. In addition, the average fracture spacing is increased and the initial peak load is also increase with the increasing of the concrete strength value, but the mechanical capacities of the concrete has little influence on the ultimate load capacities of the specimen. Keywords: Numerical test; reinforcement concrete, crack distribution, 3D

Model Testing and Analysis Study on Shear Strength of Rock Mass Containing Multiple Cracks under Compression-Shearing Loading

2008 ◽  
Vol 33-37 ◽  
pp. 617-622
Author(s):  
Wei Shen Zhu ◽  
Bin Sui ◽  
Wen Tao Wang ◽  
Shu Cai Li
Keyword(s):  
Shear Strength ◽  
Rock Mass ◽  
Rock Sample ◽  
Failure Process ◽  
Jointed Rock ◽  
Multiple Cracks ◽  
Test Results ◽  
Failure Model ◽  
Two Phase ◽  
Bridge Failure

Two-phase modelling testing was performed to study the shear strength of rock bridges of jointed rock mass in this paper. The failure process of rock sample containing multiple collinear cracks was observed. Based on theory of fracture mechanics and analytical method, a rock-bridge failure model was proposed and the expression of shear strength was derived. Comparison of calculated shear strength and the model test results was made and they agree well.

Experimental Research on Failure Modes of Specimen Containing Non-Coplanar Joints

2013 ◽  
Vol 779-780 ◽  
pp. 332-336
Author(s):  
Ping Cao ◽  
Wen Cheng Fan ◽  
Ke Zhang
Keyword(s):  
Shear Strength ◽  
Failure Mode ◽  
Failure Modes ◽  
Cement Mortar ◽  
Failure Process ◽  
Jointed Rock ◽  
Important Relationship ◽  
Initial Setting ◽  
Series Of Experiments ◽  
Dip Angle

To study the failure mechanism and failure mode of jointed rock under compressive-shear, many rock-like material specimens containing non-coplanar joints were made and a series of experiments were carried out. In the experiments, mica sheets were used as joint fillings, cement mortar was selected as rock-like material. Joints were made by inserting the mica sheet in cement mortar before initial setting. Mica sheets were left down as joint fillings. The results of experiments show that the dip angles of major joint have important influence on the failure mode of specimens. And the emerging position of wing cracks which exist in the prophase of specimens failure process changes with the dip angle. The shear strength of specimens has an important relationship with the dip angle of major joints. The smallest shear strength happens in the specimen with a joint angle of 15°, while the biggest value happens in 60°.

Stress Distribution Rule of Reinforced Concrete Specimen under Uniaxial Tension

2011 ◽  
Vol 117-119 ◽  
pp. 53-57
Author(s):  
Juan Xia Zhang ◽  
Xian Zhang Guo ◽  
Sheng Guang Zhuo ◽  
Chun An Tang
Keyword(s):  
Reinforced Concrete ◽  
Stress Distribution ◽  
Failure Process ◽  
Numerical Test ◽  
Concrete Specimen ◽  
Concrete Cover ◽  
Uniaxial Tensile ◽  
Fracture Spacing ◽  
Distribution Rule ◽  
Cover Thickness

A numerical test code named RFPA (Realistic Failure Process Analysis) was used to investigate the stress filed transformation process of the reinforced concrete specimen under uniaxial tensile loading. The periodically distributed fracture spacing phenomenon exists in the reinforced concrete structure and the concrete cover thickness was an important factor influence the average crack spacing and crack number. The numerical simulation results show that the stress fields on the concrete between the two adjacent cracks go through a variation process from tensile stress to compressive stress with the increasing of the concrete cover thickness value. It is clear that the stress distribution and fracture spacing were related to the concrete cover thickness under the condition that the materials characteristics were certain (such as concrete and reinforcement materials).In addition, if there was a new crack produced, the location was sure in the middle of the two adjacent cracks since the maximum stress occurred in the middle of the two adjacent cracks. So, it indicates that the concrete cover thickness can influence the average fracture spacing and the crack number in the reinforced concrete prism specimen.

scholarly journals Numerical Test Study of the Microscale Failure Modes and Fractal Analysis of Lower Cambrian Shale Based on Digital Images

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Hengtao Cui ◽  
Zhonghu Wu ◽  
Liping Li ◽  
Jing Wang ◽  
Shuguang Song ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Failure Modes ◽  
Fractal Theory ◽  
Failure Process ◽  
Numerical Test ◽  
Confining Pressure ◽  
Guizhou Province ◽  
Internal Damage ◽  
Damage And Fracture ◽  
Confining Pressures

To reveal the effect of confining pressure on the mechanical properties and rupture modes of quartz-bearing shale, the shale core of the no. 3 block of Fenggang, Guizhou Province, China, was analyzed by nuclear magnetic resonance, polarized light microscope thin section observation and identification, and core X-ray whole-rock minerals diffraction analysis to determine the distribution of shale minerals in the Niutitang Formation. On the microscale, based on digital image processing technology, this paper characterizes the nonuniformity of minerals in shale, a numerical model that can reflect the true microstructure of shale. Then, the failure process of shale under different confining pressures was simulated. The results show that when the shale is loaded with vertical displacement under different confining pressures, the compressive strength and elastic modulus of the sample change significantly. The failure mode can be roughly divided into three types: the inverted V-shaped (0 MPa, 2 MPa, and 4 MPa), V-shaped (6 MPa and 8 MPa), and inverted Z-shaped (10 MPa). Since the development of fractal theory provides a new space for studying the damage and fracture of rocks, the damage evolution and failure process of shale can also be regarded as the fractal process of cracks, in which the fractal dimension is the core parameter. The calculation is different under different stress levels. The fractal dimension under the condition of confining pressure shows that the value of the fractal dimension is greatly affected by the effect of confining pressure. When the fractal dimension is higher, the fracture mode is more complicated, and the internal damage degree is more serious. The research results provide important theoretical guidance for shale gas fracturing production.

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