scholarly journals Deformation and Failure Characteristics of Soil-Rock Mixture considering Material Composition and Random Structure

2019 ◽  
Vol 2019 ◽  
pp. 1-13 ◽  
Author(s):  
Shengnian Wang ◽  
Tingting Ji ◽  
Qinpei Xue ◽  
Zhifu Shen ◽  
Qiang Zhang
Keyword(s):  
Shear Strain ◽  
Progressive Failure ◽  
Rock Block ◽  
Random Structure ◽  
Bond Failure ◽  
Frictional Material ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Composition And Structure ◽  
Significant Phenomenon

The soil-rock mixture is a cohesive-frictional geomaterial subjected to impacts of composition and structure seriously. When it suffers from gravity or other kinds of loadings, the loss of its bearing capacity always appears a progressive failure. In this study, the ultimate criterion of the frictional material changing from the deformation stage to the failure stage is analyzed first and then the deformation and failure characteristics of the soil-rock mixture with different compositions and structures are discussed by the discrete element method. The results indicate that the deformation and failure of the soil-rock mixture under axial pressure appear a significant phenomenon of detouring around rock blocks. The bond failure zones and the ultimate shear strain increase with the increase of rock block proportion. The distribution of the bond failure zones always has a good uniformity with the inclination of rock block inclinations. The increase of cementation degree between particles expands the distribution of the bond failure zones but minifies the ultimate shear strain.

scholarly journals Numerical Simulations of the Soil–Rock Mixture Mechanical Properties Considering the Influence of Rock Block Proportions by PFC2D

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5442
Author(s):  
Wenwei Gao ◽  
Hairong Yang ◽  
Le Wang ◽  
Ruilin Hu
Keyword(s):  
Mechanical Properties ◽  
Numerical Models ◽  
Axial Strain ◽  
Strain Curve ◽  
Physical And Mechanical Properties ◽  
Rock Block ◽  
Particle Flow Code ◽  
Random Structure ◽  
Block Rotation ◽  
Deformation And Failure

Soil–rock mixtures (S-RMs), as a kind of special engineering geological material, need to be studied because of the special structure and complex movement mechanism of their rock blocks, their physical and mechanical properties, and the factors underlying rock block movement in the process of their deformation and failure. In this paper, a series of discrete-element numerical models are constructed in particle flow code software (PFC2D). First, the random structure numerical models of S-RMs with different rock block proportions are established. Then, the parameters of the soil meso-structure are inversed by the biaxial simulation test, and a series of biaxial compressive tests are performed. The characteristics of stress and strain, deformation and failure, and rock block rotation and energy evolution are systematically investigated. The results show the following. (1) As the rock block proportion (confining pressure 0.5 MPa) increases, the peak strength of increases, the fluctuations of the post-peak become more obvious, and the dilatancy of the sample increases. (2) As the rock block proportion increases, the width of the shear band increases, the distribution of cracks becomes more complex and dispersed, and the range of the shear zone increases. (3) The number of rock blocks with rotation also increases significantly as rock block proportion increases, and the rotation angles are mostly between −5° and 5°. (4) The strain energy of S-RMs with different rock block proportions follows the same change rule as axial strain, showing a trend of first increasing and then decreasing, like the stress–strain curve.

Size Effect in Plastic Deformation and Failure of Metallic Glasses

2020 ◽  
Vol 405 ◽  
pp. 212-216
Author(s):  
Jozef Miškuf ◽  
Kornel Csach ◽  
Alena Juríková ◽  
Mária Demčáková ◽  
Mária Demčáková ◽  
...  
Keyword(s):  
Cell Morphology ◽  
Metallic Glasses ◽  
High Strength ◽  
Dimple Size ◽  
Deformation And Failure ◽  
Composition And Structure ◽  
Instantaneous Deformation ◽  
20 Nm ◽  
Short Time ◽  
Stored Elastic Energy

Depending on the composition and structure of metallic glasses cells with the dimensions in the range from tenths nanometers to tenths micrometers were observed on the ductile fracture surface. The variation in dimple size was compared with the serrations presented on the loading curve at the nanoindentation of the metallic glasses with different compositions. Higher instantaneous deformation can be connected with simultaneous shearing at more suitable shear band configurations. The cell morphology with the various cell sizes is observed at the failure of the metallic glasses. At the failure of high strength metallic glasses, the cells are formed in short time due to the release of high amount of stored elastic energy. In this case the uniform cell morphology with the cell size of about 20 nm is observed.

scholarly journals Deformation and failure characteristics of weathered granite under uniaxial compression

AIP Advances ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 075222 ◽  
Author(s):  
Lingfan Zhang ◽  
Duoxing Yang ◽  
Zhonghui Chen
Keyword(s):  
Uniaxial Compression ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Weathered Granite

scholarly journals Experimental study on deformation and failure characteristics of discontinuous prefabricated fractured tuff

2019 ◽  
Vol 16 (5) ◽  
pp. 862-874
Author(s):  
Yang Song ◽  
Heping Wang ◽  
Meng Ren
Keyword(s):  
Shear Failure ◽  
Failure Process ◽  
Dissipated Energy ◽  
Uniaxial Compression Test ◽  
Tensile Shear ◽  
Joint Spacing ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Peak Intensity ◽  
Dip Angle

Abstract To study more fully the characteristic law of deformation and failure of tuff jointed rock mass of prefabricated parallel discontinuous joint test specimens, the uniaxial compression test was used. The stress–strain curve, peak intensity, deformation parameters, energy characteristics, etc., of the rock test specimens were systematically studied under different combinations of joint dip angle and joint spacing. The research found that: (1) during the failure process of tuff, the peak intensity and elastic modulus followed a U-shaped change pattern and the minimum value was reached when α = 60°; (2) the fracture modes of test specimens with different joint dip angles were different. When α = 30° and 45°, failure characteristics were mixed modes of tensile or tensile shear failure. When α = 60°, failure characteristics were shear. At α = 75°, the failure characteristic was tensile shear failure. (3) The absorbed and dissipated energy of the rock increased nonlinearly at each stage of deformation. (4) We quantified rock energy damage through a correlation between dissipated energy and absorbed energy of the rock in the process of energy evolution, and obtained an evolution of the relationship between the dissipated energy ratio, crack dip angle and crack spacing. Based on different fracture distribution methods and according to the strain equivalence principle, the constitutive equation of the pre-peak rock damage was obtained.

Numerical Investigation of Post Buckling Strength and Failure Modes in Advanced Grid Stiffened Structure under Thermal-Mechanical Loads

2007 ◽  
Vol 334-335 ◽  
pp. 613-616
Author(s):  
Rui Xiang Bai ◽  
Bo Chen ◽  
Cheng Yan ◽  
Lin Ye ◽  
Ze Cheng Li ◽  
...  
Keyword(s):  
Failure Modes ◽  
Mechanical Load ◽  
Progressive Failure ◽  
Shear Deformation Theory ◽  
Failure Behavior ◽  
Linear Deformation ◽  
Failure Characteristics ◽  
Buckling Strength ◽  
Stiffened Structures ◽  
Post Buckling

This work investigated the post buckling strength and failure behavior of advanced grid stiffened structures (AGS) under thermal-mechanical load using a finite element method. Based on the first order shear deformation theory (FSDT), Von Karman non-linear deformation assumption, and a progressive failure criterion, the buckling, large deformation，local failure modes in the AGS were studied. The thermal effect was also analyzed. By some numerical examples, the failure characteristics of the AGS were discussed.

scholarly journals Deformation and Failure Characteristics of the Roof in an Unsupported Area during Rapid Driving of Coal Roadway

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Sen Yang ◽  
Xinzhu Hua ◽  
Xiao Liu ◽  
Enqian Wang ◽  
Chen Li
Keyword(s):  
Thin Plate ◽  
Simulation Software ◽  
Failure Characteristics ◽  
Deformation And Failure ◽  
Bending Deformation ◽  
Coal Roadway ◽  
Driving Speed ◽  
Support Force ◽  
Supporting Force ◽  
Influence Degree

In order to study the deflection and failure characteristics of the goaf roof, a mechanical model of the goaf thin plate is established and the deflection expression of the goaf roof is obtained. The results show the following: (1) under the action of single factor, the roof deflection is more sensitive to the interaction of unsupported roof distance and load, but less sensitive to the support force. (2) The influence degree of each factor on the deflection of the thin plate in the unsupported top area is as follows: unsupported roof distance and load interaction > unsupported roof distance and supporting force > supporting force and load. (3) The roof bending deformation is slow when the unsupported roof distance is within 0–2.3 m. When the vacant distance of the roof is more than 2.3 m, the bending deformation of the roof is accelerated. Using FLAC3D numerical simulation software, the distribution of vertical stress and displacement under different space distances is analyzed and the reasonable space distance is 2.0 m. Through the application of 150802 machine roadway in Liuzhuang coal mine, the driving speed of the coal roadway is improved and the monthly footage of coal roadway reaches 506 m.

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