scholarly journals Identification of Initial Crack and Fracture Development Monitoring under Uniaxial Compression of Coal with High Bump Proneness

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Zuoqing Bi ◽  
Han Liang ◽  
Qianjia Hui
Keyword(s):  
Rock Burst ◽  
Uniaxial Compression ◽  
Failure Process ◽  
Strain Curve ◽  
Initial Crack ◽  
Internal Crack ◽  
Uniaxial Compression Test ◽  
Stress Strain ◽  
Crack Distribution ◽  
Fracture Development

The rock burst proneness of coal is closely related to the coal mass structure. Therefore, the initial crack distribution of high burst proneness coal, its fracture development, and failure process under loading conditions are of great significance for the prediction of rock burst. In this study, high burst proneness coal is used to prepare experiment samples. The surface cracks of the samples are identified and recorded. The internal crack of the sample is detected by nuclear magnetic resonance (NMR) technology to determine the crack ratio of each sample. Then, 3D-CAD technology is used to restore the initial crack of the samples. Uniaxial compression test is carried out, and AE properties are recorded in the test. The stress-strain curve, the distribution of the fractural points within the sample at different stress states, and the relationship between ring count and stress are obtained. Results show that the stress-strain curves of high burst proneness coal are almost linear, to which the stress-ring count curves are similar. The distributions of fractural points in different bearing states show that the fracture points emerge in the later load stage and finally penetrate to form macrofracture, resulting in sample failure. This study reveals the initial crack distribution of coal with high burst proneness and the fracture development under bearing conditions, which provides a theoretical basis for the prediction technology of rock burst and technical support for the research of coal structure.

scholarly journals Proposed Constitutive Law of Uniaxial Compression for Concrete under Deterioration Effects

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2048 ◽  
Author(s):  
Yiwei Gao ◽  
Xuhua Ren ◽  
Jixun Zhang ◽  
Lingwei Zhong ◽  
Shuyang Yu ◽  
...  
Keyword(s):  
Uniaxial Compression ◽  
Failure Process ◽  
Strain Curve ◽  
Ductile Deformation ◽  
Deformation Capacity ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
New Model ◽  
Freeze Thaw ◽  
Prediction Curve

In order to study the ductile deformation characteristics and failure process of plain concrete under uniaxial compression, this paper proposes a new constitutive model. The new model was used to fit and analyze the constitutive curve of concrete under uniaxial compressive under various degradation forms and was compared with the traditional constitutive models. Finally, the new model was used to quantitatively analyze and predict the stress–strain curve of concrete in different degradation periods of a set of freeze–thaw measured data. The results show that, compared with the traditional constitutive model, the new model is simple in form and has few parameters, and the numerical value of the parameter can reflect the ductile deformation capacity of concrete. The fitting curve of the new model has the highest fitting degree with the measured stress–strain curve of concrete, and the goodness of fit (R2) is also the largest. The new model is suitable for fitting the stress–strain curve of concrete under uniaxial compression under various deteriorating forms, and the degree of fit between the constitutive prediction curve and the measured curve is high. It can be seen from the fitting results of the new model parameters that the ductile deformation capacity of concrete decreases first and then increases slightly, which is inconsistent with the law of gradual deterioration of strength. There is a minimum moment of ductility deformation capacity of concrete (MDC). The MDC of O-C40 concrete is about 114 freeze–thaw cycles, and the MDC of O-C50 concrete is about 116 freeze–thaw cycles; the degree of fit between the constitutive prediction curve and the measured curve is high. We hope that the improvement mentioned offers valid reference to the study of ductile deformation characteristics and failure process of compressed concrete under different deterioration forms.

scholarly journals Numerical Simulation of Static Stress-Strain Relationship and Failure Mode for Freeze-Thaw Concrete

2020 ◽  
Vol 2020 ◽  
pp. 1-9
Author(s):  
Xiaolin Yang ◽  
Genhui Wang ◽  
Hongzhao Li ◽  
Jiang Fan
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Uniaxial Compression ◽  
Strain Curve ◽  
Stress And Strain ◽  
Uniaxial Compression Test ◽  
Stress Strain ◽  
Element Analysis ◽  
Freeze Thaw ◽  
Thaw Cycle

To analyze the causes of failure of cubic concrete test specimens under quasistatic axial compression, microtests and finite element numerical simulation of C40 cubic concrete test specimens were conducted without the freeze-thaw cycle and with 50 freeze-thaw cycles. Based on the analysis of the microstructure of concrete, the variation law of the full curve of stress and strain was analyzed by the uniaxial compression test and the splitting tensile test of concrete. The results show that freeze-thaw damage is mainly caused by the cyclic reciprocating stress of the micropore structure inside the concrete. The peak stress of concrete uniaxial compression and splitting tensile strength gradually decrease with the number of freeze-thaw cycles; the full stress-strain curve tends to shift downward and to the right. Finite element analysis shows that under the quasistatic uniaxial compression loading condition, the stress and strain fields in the test specimens are symmetrically distributed but nonuniform. The plastic deformation of the concrete weakens the nonuniformity of the stress distribution and is closer to the experimental failure morphology.

scholarly journals Effect of Water Saturation on Stress-Strain Curve of Rocks in Uniaxial Compression

2017 ◽  
Vol 133 (6) ◽  
pp. 107-115 ◽  
Author(s):  
Minami KATAOKA ◽  
Tianshu BAO ◽  
Kimihiro HASHIBA ◽  
Katsunori FUKUI
Keyword(s):  
Uniaxial Compression ◽  
Water Saturation ◽  
Strain Curve ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Effect Of Water

Research of Inclination Angle Effect on Joint Rock Macromechanical Parameters

2011 ◽  
Vol 704-705 ◽  
pp. 1089-1094
Author(s):  
Yan Feng Feng ◽  
Tian Hong Yang ◽  
Hua Wei ◽  
Hua Guo Gao ◽  
Zhe Zhang
Keyword(s):  
Rock Mass ◽  
Uniaxial Compression ◽  
Inclination Angle ◽  
Damage Mechanics ◽  
Deformation Modulus ◽  
Strain Curve ◽  
Uniaxial Compression Test ◽  
Joint Rock Mass ◽  
Test Result ◽  
Joint Rock

The joint of rock mass influences and controls the rock mass intensity, deformation characteristics and instability failure in the rock engineering to a great extent. Using the similar material simulation is of different inclination angle of non-penetration jointing and non-jointing rock mass, through using rigid servo compression machine to carry uniaxial compression test, we get a nearly same trend of joint rock mass stress-strain curve of different angle, the curve of inclination angle of 45 is analyzed, the test result shows that the compressive strength first decreases and then increases gradually with the increase of rock inclination angle. The compression intensity is its minimum when of the inclination angle of 45°, and the deformation modulus first decreases and then increases, but deformation modulus of 30° is its minimum. In addition, through the use of developed RFPA2D system to simulate on trial uniaxial compression value based on microscopic damage mechanics, we get the conclusion that the numerical analysis and test result is fitting approximately, it is validated that the numerical model can simulate joint rock well. Keywords: joint rock mass, inclination angle, uniaxial compression, compressive intensity, deformation modulus

scholarly journals Three-Dimensional Reconstruction and Numerical Simulation Analysis of Acid-Corroded Sandstone Based on CT

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Zizhen Miao ◽  
Shuguang Li ◽  
Jiangsheng Xie ◽  
Runke Huo ◽  
Fan Ding ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Uniaxial Compression ◽  
Damage Evolution ◽  
Simulation Analysis ◽  
Acid Corrosion ◽  
Three Dimensional ◽  
Strain Curve ◽  
Uniaxial Compression Test ◽  
Evolution Law ◽  
Simulation Results

Due to its unique technological characteristics, coal mining and production often encounter an acid corrosion environment caused by acid gases. Acid erosion and a series of chemical reactions caused by it often led to the deterioration of coal, rock, support structure, etc. and induced serious safety accidents. To further explore the macro-mesoscopic damage evolution law and failure mechanisms of rock masses under corrosion conditions through numerical simulation, a zonal refined numerical model that can reflect the acid corrosion characteristics of sandstone is established based on CT and digital image processing (DIP). The uniaxial compression test of corroded sandstone is simulated by ABAQUS software. Comparing the numerical simulation results with the physical experiment results, we found that the three-dimensional finite element model based on CT scanning technology can genuinely reflect sandstone’s corrosion characteristic. The numerical simulation results of the stress-strain curve and macroscopic failure mode of the acid-corroded sandstone are in good agreement with the experimental results, which provides a useful method for further studying the damage evolution mechanism of the acid-corroded rock mass. Furthermore, the deformation and damage evolution law of the corroded sandstone under uniaxial compression is qualitatively analyzed based on the numerical simulation. The results show that the rock sample’s axial displacement decreases gradually from top to bottom under the axial load, and the vertical variation is relatively uniform. In contrast, the rock sample’s removal gradually increases with the increase of axial pressure, and the growth presents a certain degree of nonuniformity in the vertical. The acid-etched rock sample’s damage starts from both the end and the middle; it first appears in the corroded area. Moreover, with the displacement load increase, it gradually develops and is merged in the middle of the rock sample and forms macroscopic damage.

Experimental Research on Deformation Properties of Gangue-Paste Filling Material in Mine

2013 ◽  
Vol 734-737 ◽  
pp. 746-750
Author(s):  
Jun Wei Shi
Keyword(s):  
Mechanical Properties ◽  
Uniaxial Compression ◽  
Triaxial Compression ◽  
Strain Curve ◽  
Filling Material ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Deformation Stage ◽  
Plastic Hardening ◽  
Softening Stage

According to the mechanical properties of paste filling body under special environment such as high temperature high humidity high stress and high airtight) in gob, mechanical properties of gangue-paste filling body was studied with the method of field core and laboratory test. The complete stress-strain curve of filling body under the condition of uniaxial and triaxial and the ultimate compressive strength under different confining pressure station were obtained through uniaxial and triaxial compression test. Six stages of uniaxial compression complete stress-strain curve (compression stage, elastic deformation stage, non-stable developing stages, plastic hardening stage, stress softening stage and residual deformation stage) were improved and developed. The deformation characteristics of filling body under triaxial compression were different from that under uniaxial compression. Namely the deformation of filling body under triaxial compression only appeared two deformation stages: linear deformation stage and plastic hardening stage, but had no softening stage basically under different confining pressures, which was benefit for controlling the ground subsidence and preventing the ground buildings.

Experimental Equipment Research on Uniaxial Compression Stress-Strain Curve of Concrete

2010 ◽  
Vol 163-167 ◽  
pp. 1333-1338
Author(s):  
Hai Bin Chen ◽  
You Po Su ◽  
Yu Min Zhang ◽  
Li Na Wang
Keyword(s):  
Structural Analysis ◽  
Strain Rate ◽  
Uniaxial Compression ◽  
Theoretical Basis ◽  
Indirect Method ◽  
Strain Curve ◽  
Experimental Equipment ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Loading System

The constitutive relation of concrete under uniaxial compression is the essential theoretical basis for structural analysis of concrete. Because of lack of sufficient stiffness for ordinarily tester, stable falling branch of stress-strain curve cannot be obtained. The common methods to increase rigidity of loading system include direct and indirect method. The condition of realizing the stress-strain complete curve for concrete uniaxial compression is derived. A set of stiffness experimental equipment is designed by using the indirect method, which has the advantages of simple, dependable and strong adaptability. Experiment shows that stress-strain complete curve of uniaxial compression under different strain rate could be achieved by using this equipment and electro-hydraulic loading system of MTS co. ltd. It will lay foundation for putting forward the stress-strain curve equation of uniaxial tension and compression under considering the effect of strain rate. It can provide theoretical basis for structural analysis of concrete.

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