scholarly journals Numerical Simulation of Rock Uniaxial Compressive Strength and Deformation Failure Law under Different Size Conditions

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Zhichao Tian ◽  
Chunan Tang ◽  
Hao Li ◽  
Hui Xing ◽  
Xiangda Ning
Keyword(s):  
Numerical Simulation ◽  
Shear Failure ◽  
Process Analysis ◽  
Failure Process ◽  
Simulation Software ◽  
Diameter Ratio ◽  
Rock Engineering ◽  
Rock Model ◽  
Important Position ◽  
High Level

Rock engineering occupies an important position in the 21st century. In the face of rock engineering disasters, we are only looking for the essential problems through experiments on rocks, but rock experiments cannot be realized in large numbers, so the article uses numerical simulation software RFPA (Realistic Failure Process Analysis) 2D Basic to simulate rock under different size conditions numerically. In this paper, a rock model with a diameter of 50 mm is used for simulation research. Meanwhile, five calculation models of height-to-diameter ratios of 1.0, 1.5, 2.0, 2.5, and 3 are used. Through simulation calculation, we find that the rock model failure is more than complicated when the value of the height-to-diameter ratio is exceedingly low (1), but as the height-to-diameter ratio increases, the failure mode will become simpler. The stress-concentrated failure will be in the form of axial failure. When the height-to-diameter ratio increases (1.5–2), other damage cracks appear on the basis of axial cleavage failure. As the height-to-diameter ratio continues to increase (about 2.5), only shear failure occurs. When the height-to-diameter ratio reaches a relatively high level (3), there will be both axial rip and other damage. When the height-to-diameter ratio is oversize, there will be both axial rip failure and end damage.

Numerical Simulation of Gas Distribution and Mined Seepage Passage with the Pressure Relief of Short Distance Protective Coal Stratum

2011 ◽  
Vol 105-107 ◽  
pp. 1517-1520
Author(s):  
Yong Jun Zhang ◽  
Nian Jie Ma ◽  
Zi Min Zhang ◽  
Tian Rang Jia
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Gas Permeability ◽  
Process Analysis ◽  
Failure Process ◽  
Numerical Approach ◽  
Gas Seepage ◽  
Coal Rock ◽  
Rock Model ◽  
Stress Damage

With the full consideration of the heterogeneity, existing joints, and cracks in the rock, the coupled gas-rock model for investigating the failure process of coal-rock is established by introducing the related equations governing the evolution of stress, damage and gas permeability along with the deformation of coal and rock. A numerical approach of realistic failure process analysis (RFPA) to simulate the stratum movement, layer separation, the whole collapse progresses, and gas permeability changing of the protected coal seam is proposed. The numerical simulation results well displayed the whole processes of the cracks growth of gas seepage passage and the change of gas permeability for the closed distance protected coal seam. It can be seen from the distribution of acoustic emission in the space that the stratum failure is transferred from deeper to surface. By the analysis of the stress fields changing, the reasons of the gas permeability improvement of the protected coal seam are presented.

scholarly journals Numerical Simulation of Rock Failure Process with a 3D Grain-Based Rock Model

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Zengwei Zhang ◽  
Fan Chen ◽  
Chao Zhang ◽  
Chao Wang ◽  
Tuo Wang ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Mechanical Characteristics ◽  
Failure Process ◽  
Wellbore Stability ◽  
Rock Excavation ◽  
Rock Failure Process ◽  
Rock Model ◽  
Walled Cylinder

A grain-based rock model was developed and applied to study mechanical characteristics and failure micromechanics in thick-walled cylinder and wellbore stability tests. The rock is represented as an assembly of tetrahedral blocks with bonded contacts. Material heterogeneity is modeled by varying the tensile strength at the block contacts. This grain-based rock model differs from previous disk/sphere particle-based rock models in its ability to represent a zero (or very low) initial porosity condition, as well as highly interlocked irregular block shapes that provide resistance to movement even after contact breakage. As a result, this model can reach higher uniaxial compressive strength to tensile strength ratios and larger friction coefficients than the disk/sphere particle-based rock model. The model captured the rock fragmentation process near the wellbore due to buckling and spalling. Thin fragments of rock similar to onion skins were produced, as observed in laboratory breakout experiments. The results suggest that this approach may be well suited to study the rock disaggregation process and other geomechanical problems in the rock excavation.

scholarly journals Numerical Simulation Virtual Test of Torsion Shear for Asphalt Mixture

2019 ◽  
Vol 2019 ◽  
pp. 1-21
Author(s):  
Jun Xie ◽  
Yougang Yang
Keyword(s):  
Numerical Simulation ◽  
Shear Failure ◽  
Failure Process ◽  
Asphalt Mixture ◽  
Test Method ◽  
Reconstruction Method ◽  
Virtual Test ◽  
Torsional Shear ◽  
Shear Process ◽  
Air Void

In order to analyze the torsional shear process of asphalt mixtures in a microscopic view, the numerical simulation of a torsional shear test of an asphalt mixture was carried out by discrete element method. Based on the defects of existing algorithms, the method of random reconstruction of the existing 3D model of the asphalt mixture was improved, and a new reconstruction method was proposed. A 3D numerical model of the asphalt mixture contained irregular-shaped coarse aggregate, mineral gradation, and asphalt mortar; furthermore, the particle algorithm established the air void distribution. Then, the numerical simulation of the asphalt mixture’s torsional shear was completed; in addition, the stress, displacement, and contact of the specimens at each stage were analyzed. The results showed that the stress and displacement in different stages changed greatly with the loading, i.e., the crack generated from a weak point on the surface and then spread to the ends with an oblique angle of about 45°. At the same time, the shear failure process of the asphalt mixture was studied. The virtual test method could accomplish the implementation of the numerical simulation of torsional shear; it also provided a good research method for analysis of the asphalt mixture’s shear failure process.

The Impact Analysis of Ground Stability Caused by Exploiting Underground Coal

2011 ◽  
Vol 243-249 ◽  
pp. 3147-3150
Author(s):  
Shu Xian Liu ◽  
Xiao Gang Wei ◽  
Shu Hui Liu ◽  
Li Ping Lv
Keyword(s):  
Numerical Simulation ◽  
Coal Mining ◽  
Impact Analysis ◽  
Shear Failure ◽  
Failure Process ◽  
Wall Rock ◽  
Strong Impact ◽  
Element Analysis ◽  
Deformation And Failure ◽  
The Impact

Disaster caused by exploiting underground coal is due to original mechanical equilibrium of underground rock has been destroyed when underground coal is exploited. And Stress redistribution and stress concentration of wall rock in the goaf happened too. As many complex factors exist such as complex structures of ground, multivariate stope boundary conditions, many stochastic mining factors and so on, it is difficult to evaluate the damage of the geological environment caused the excavation by surrounding underground coal accurately. Besides that, the coexistence of continuous and discontinuous of deformation and failure of wall rock make a strong impact on the ground, and the co-exist of tension, compression and shear failure also pay a great deal contribution to the destroy. Due to the mechanical property and deformation mechanism of goaf are complex , changeable, nonlinear and probabilistic, which changes with in space and time dynamically, it can not be studied analytically by the classical mathematical model and the theory of mechanics computation. Through finite element analysis software ABAQUS, a numerical simulation of the process of underground coal mining have been made. After make a research of the simulation process, it shows the change process of stress environment of wall rock and deformation and failure process of rock mass during the process of coal mining. The numerical simulation of the process can provide theoretical basis and technical support to the protection and reinforcement of laneway the process of coal excavation. Besides that, it also provides a scientific basis and has a great significance to reasonable Excavation and control of mind-out area.

Numerical Simulation on Fracture Formation on Surfaces of Bi-Layered Materials

2007 ◽  
Vol 353-358 ◽  
pp. 993-996
Author(s):  
Tian Hui Ma ◽  
Ju Ying Yang ◽  
Zheng Zhao Liang ◽  
Yong Bin Zhang ◽  
Tao Xu
Keyword(s):  
Numerical Simulation ◽  
Numerical Solutions ◽  
Process Analysis ◽  
Failure Process ◽  
Layered Materials ◽  
Numerical Code ◽  
Material Layer ◽  
Fracture Formation ◽  
Constant State ◽  
The Individual

Fracture formation on surfaces of bi-layered materials is studied numerically. A simplified two-layered materials model like growing tree trunk is present. This work is focused on patterns of fractures and fracture saturation. We consider the formation of crack pattern in bark as an example of pattern formation due to expansion of one material layer with respect to another. As a result of this expansion, the bark stretches until it reaches its limit of deformation and cracks. A novel numerical code, 3D Realistic Failure Process Analysis code (abbreviated as RFPA3D) is used to obtain numerical solutions. In this numerical code, the heterogeneity of materials is taken into account by assigning different properties to the individual elements according to statistical distribution function. Elastic-brittle constitutive relation with residual strength for elements and a Mohr-Coulomb criterion with a tensile cut-off are adopted so that the elements may fail either in shear or in tension. The discontinuity feature of the initiated crack is automatically induced by using degraded stiffness approach when the tensile strain of the failed elements reaching a certain value. The different patterns are obtained by varying simulation parameters, the thickness of the material layer. Numerical simulation clearly demonstrates that the stress state transition precludes further infilling of fractures and the fracture spacing reaches constant state,i.e. the socalled fracture saturation. It also indicates that RFPA code is a viable tool for modeling fracture formation and studying fracture patterns.

Numerical Simulation of Compressive Experiment of Coal Seam in Deep Underground for Geological Storage of Carbon Dioxide

2013 ◽  
Vol 387 ◽  
pp. 189-192
Author(s):  
Feng Shan Han ◽  
Xin Li Wu
Keyword(s):  
Numerical Simulation ◽  
Coal Seam ◽  
Shear Failure ◽  
Lateral Pressure ◽  
Failure Process ◽  
Absorption Capacity ◽  
Geological Storage ◽  
Modeling Tools ◽  
Storage Reservoirs ◽  
Deep Underground

The geological storage of has been recognized as an important strategy to reduce emission in the atmosphere. Coal seam has strong absorption capacity for , hence the coal seam can be used as geological storage reservoirs, simple and easy to use modeling tools would be valuable in assessing the performance of deep underground geological storage. In this paper failure process of coal seam in deep underground under triaxial compressive experiment is presented by numerical simulation. That is of significance and valuable to those subjects of investigation of strength of coal seam in deep underground and mechanism of propagation and coalescence and evolvement of crack for coal seam in deep underground, it is shown by numerical simulation that failure shape of coal seam in deep underground under triaxial compressive experiment of lateral pressure of 25Mpa is typically shear failure, and characteristic of deformation is obviously elastic-brittle, which is significance to understand the performance of the coal seam in deep underground

Numerical Investigation for Fracture Saturation in Multilayer Sedimentary Rock in Unsymmetrical Case

2013 ◽  
Vol 690-693 ◽  
pp. 3050-3053
Author(s):  
Feng Shan Han ◽  
Li Song
Keyword(s):  
Numerical Simulation ◽  
Layer Thickness ◽  
Sedimentary Rock ◽  
Process Analysis ◽  
Failure Process ◽  
Bottom Layer ◽  
Thickness Ratio ◽  
Fracture Spacing ◽  
Layer Thickness Ratio ◽  
Rock Failure Process

Opening mode fractures in multilayer sedimentary rock often are periodically distributed with fracture spacing scaled to the thickness of the fractured layer. In this paper, based on Rock Failure Process Analysis Code RFPA2D, a three layer model with a central layer and with the different thickness top and bottom layer, progressive formation in multilayer sedimentary rock at fracture saturation in unsymmetrical case is simulated. We investigate the change of the critical fracture spacing to layer thickness ratio as a function of the thickness of the top layer where the bottom layers is much thicker (5 times) than the fractured layer called the unsymmetrical case, in this unsymmetrical case, fracture saturation is simulated. By numerical simulation of RFPA2D, the critical spacing to layer thickness ratio decreases and tend to the same constant value as the thickness of the top layer increases. Numerical simulation shown that for the unsymmetrical case, if the adjacent layers are thicker than 1.5 times the thickness of the fractured layer, the multilayer sedimentary rock can be treated approximately as a system with infinitely thick top and bottom layers at fracture saturation.That should be useful in the design of engineering systems and in the prediction of fracture spacing in hydrocarbon reservoirs and groundwater aquifers.

Application of RFPA2D in Sublevel Caving Mining Extra-Thick Coal Seams

2008 ◽  
Vol 575-578 ◽  
pp. 1246-1251 ◽  
Author(s):  
Hua Nan ◽  
Tao Xu ◽  
Zhi Dong Wei
Keyword(s):  
Numerical Simulation ◽  
Process Analysis ◽  
Failure Process ◽  
Coal Seams ◽  
Simulation Test ◽  
Parameters Selection ◽  
Sublevel Caving ◽  
High Efficient ◽  
Measurement Results ◽  
Suitable Arrangement

On the basis of suitable arrangement for the special stress surrounding and parameters selection, Realistic Failure Process Analysis 2-D (RFPA2D) numerical simulation of extra-thick coal seams’ displacement and failure is carried out. It’s proved that the numerical simulation results are consistent with the in-sit measurement results of top coal’s advance supporting stress and deep-hole displacement. So application of RFPA2D in sub-level caving mining extra-thick coal seams is reliable. It’s also proved that application of RFPA2D in sub-level caving mining can do great help to study the nature of top coal’s displacement, fragmentation and failure process of extra-thick coal seams. As the top coal’s displacement and failure situation under certain circumstance can be forecasted by RFPA2D numerical simulation, the most suitable top coal thickness under certain circumstance can be predicted by RFPA2D numerical simulation test, which can do great benefit to extra-thick coal seams’ safe and high efficient mining.

Numerical Simulation of Fracture Saturation in Multilayer Materials in Symmetric Case

2011 ◽  
Vol 704-705 ◽  
pp. 641-644
Author(s):  
Feg Shan Han
Keyword(s):  
Numerical Simulation ◽  
Layer Thickness ◽  
Process Analysis ◽  
Failure Process ◽  
Bottom Layer ◽  
Symmetric Case ◽  
Thickness Ratio ◽  
Central Layer ◽  
Layer Thickness Ratio ◽  
Multilayer Materials

Using Realistic Failure Process Analysis Code RFPA2D, a three layer materials model with a central layer and with the same thickness top and bottom layer, progressive formation of fracture saturation in multilayer materials is simulated in all case by numerical simulation. Our numerical simulation recurrence the phenomenon of fracture saturation in multilayer materials. numerical simulation shown that for the symmetric case the spacing of these fractures at fracture saturation are approximately the same and lineally related to thickness of the fractured layer. We investigate that the critical fracture spacing to layer thickness ratio is function of the thickness ratio of the top and bottom layers to central layer at fracture saturation. numerical simulation shown that for the symmetric case the critical spacing of fractures to layer thickness ratio decreases rapidly and tends to a constant value.

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