Effect of Non-Homogeneity on Limit Bearing Capacity of Rock Block

2008 ◽  
Vol 33-37 ◽  
pp. 631-638
Author(s):  
Li Song ◽  
Tao Xu ◽  
Ying Yan Xie
Keyword(s):  
Numerical Simulations ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Process Analysis ◽  
Failure Process ◽  
Functional Relation ◽  
Acoustic Emissions ◽  
Rock Block ◽  
Homogeneous Material ◽  
Engineering Structures

Rock is a typical non-homogeneous material. The behavior of a rock block under compression and the process of micro-fracture in that block are phenomena of considerable interest in understanding the strength characterization of brittle rock. In this study, the effect of the non-homogeneity on limit bearing capacity of rock block based on Rock Elasto-Plastic Failure Process Analysis code (REPFPA) are simulated and investigated. Numerical simulations find out that there exists a functional relation between the heterogeneity coefficient and the limit bearing capacity of rock block. For specimens with the same heterogeneity, however, the numerical simulations show that the failure modes depend greatly on the crack initiation location, which is found to be sensitive to the local disorder features within the specimen. In addition, the characteristics of acoustic emissions with the changing of heterogeneity coefficient were also found. These identifications are crucial for better understanding and interpreting the experimental results and consequently, improve our concepts in design or analysis of rock engineering structures.

scholarly journals Research on Failure Characteristics of Concrete Three-Point Bending Beams with Preexisting Cracks in Different Positions Based on Numerical Simulation

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Liuqun Zhao ◽  
Li Zheng ◽  
Hui Qin ◽  
Tiesuo Geng ◽  
Yonggang Tan ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Bearing Capacity ◽  
Failure Modes ◽  
Failure Process ◽  
Engineering Application ◽  
Tensile Failure ◽  
Engineering Structures ◽  
Failure Characteristics ◽  
Three Point Bending ◽  
Wide Range

Concrete three-point bending beams with preexisting cracks are widely used to study the growth process of I-II mixed mode cracks. Studying the failure characteristics of preexisting cracks at different locations on concrete three-point bending beams not only has important scientific significance but also has a wide range of engineering application backgrounds in the safety assessment of engineering structures. In this paper, through several numerical experiments, the influence of preexisting cracks at different positions on the failure characteristics of concrete three-point bending beams is studied, and three typical failure modes are obtained. The failure process of the specimens with three typical failure modes is discussed in detail, and it is pointed out that the crack failure mode is tensile failure. The change trends of bearing capacity, acoustic emission quantity, and acoustic emission energy of three typical failure modes are analyzed. The maximum bearing capacity, the maximum acoustic emission quantity, and energy of three failure modes of concrete three-point bending beams generally show an increasing trend.

scholarly journals Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-14 ◽  
Author(s):  
Tianhui Ma ◽  
Long Wang ◽  
Fidelis Tawiah Suorineni ◽  
Chunan Tang
Keyword(s):  
Failure Modes ◽  
Process Analysis ◽  
Failure Process ◽  
Effective Means ◽  
Shear Loading ◽  
Shear Stresses ◽  
Planning And Design ◽  
Rock Failure Process ◽  
Damage Process ◽  
Dip Angle

Severe damage occurs frequently in mine pillars subjected to shear stresses. The empirical design charts or formulas for mine pillars are not applicable to orebodies under shear. In this paper, the failure process of pillars under shear stresses was investigated by numerical simulations using the rock failure process analysis (RFPA) 2D software. The numerical simulation results indicate that the strength of mine pillars and the corresponding failure mode vary with different width-to-height ratios and dip angles. With increasing dip angle, stress concentration first occurs at the intersection between the pillar and the roof, leading to formation of microcracks. Damage gradually develops from the surface to the core of the pillar. The damage process is tracked with acoustic emission monitoring. The study in this paper can provide an effective means for understanding the failure mechanism, planning, and design of mine pillars.

Fracture Pattern Comparison Research of Different Types of All-Ceramic Crown

2013 ◽  
Vol 699 ◽  
pp. 480-483
Author(s):  
Cheng Fan
Keyword(s):  
Failure Modes ◽  
Process Analysis ◽  
Failure Process ◽  
Element Model ◽  
Fracture Pattern ◽  
All Ceramic ◽  
Dimensional Finite Element ◽  
The Difference ◽  
Analysis System ◽  
Ceramic Crown

All-ceramic crown restorations are more widely used. The mechanical properties of different type of all-ceramic crown are evident different because of the differences of materials and production process. To study the failure pattern of different all-ceramic crown under load, two dimensional finite element model of three different all-ceramic crown models are constructed using the RFPA (realistic failure process analysis) system in this paper. Due to the difference of stress mismatch between different porcelain layers, it is found that the failure modes of different all-ceramic crown model are significantly different in the study. The advantage of this system is that the crack initiation, propagation and failure process of all-ceramic crown can be clearly observed and the research results provide guidance for clinical application.

scholarly journals Numerical tests on thermal cracking characteristics of rocks with different scales

2018 ◽  
Vol 10 (8) ◽  
pp. 168781401879214 ◽  
Author(s):  
Yang Xiao ◽  
Rui Zhao ◽  
Qing-Xiang Huang ◽  
Jun Deng ◽  
Jun-Hui Lu
Keyword(s):  
Acoustic Emission ◽  
Thermal Destruction ◽  
Thermal Damage ◽  
Process Analysis ◽  
Failure Process ◽  
Acoustic Emissions ◽  
Thermal Cracking ◽  
Tensile Failure ◽  
Failure Patterns ◽  
Different Diameters

Realistic failure process analysis, a thermal software simulation, was used to explore the scale effect of thermal cracking of rock under the thermal–mechanical coupling loading. The patterns and characteristics of thermal destruction were analyzed by simulating the thermal cracking of rocks with the same diameter different lengths, the same length but different diameters, and the same size ratio but different sizes (same length/diameter ratio but with different diameters). The acoustic emission and energy changes were also studied during thermal destruction. The results represented that the main forms of thermal cracking are tensile failure and shear failure. The smaller the scale is (length, diameter, and size), the more complex the pattern of thermal damage exhibited as failure patterns of inverted “S” or “V.” With the increasing scale, thermal damage models were simpler. The elastic modulus was determined by the diameter of specimens, and the peak stress was determined by the length of specimens. Overall, as the scale increased, the stress intensity decreased, but the number of acoustic emissions and acoustic emission energy and the corresponding accumulation increased.

System Reliability Study Based on Bearing Capacity Update and Deformation Iteration

2011 ◽  
Vol 368-373 ◽  
pp. 1608-1612
Author(s):  
Hao Liang Zhu ◽  
Wen Bo Sun
Keyword(s):  
Bearing Capacity ◽  
System Reliability ◽  
Failure Modes ◽  
Failure Process ◽  
Scientific Basis ◽  
Structural Testing ◽  
Engineering Project ◽  
Structural Reinforcement ◽  
Distribution Parameters ◽  
Incremental Step

For the sensitive of distribution parameters of random variables, system reliability research should be focus on identifying the significant failure modes, while failure probability as a quantitative reference index, only combining both of them can better estimate system reliability. On the basis of load incremental step theory, a method for identifying the significant failure modes which could more accurately simulate the real failure process for considering the change of bearing capacity and spatial position is proposed in this paper. Then, the corresponding program is prepared with APDL on ANSYS platform. On the one hand, the efficiency and accuracy of identification is improved, on the other hand, the usefulness of this method is enhanced. Finally, the reliability of a space grid engineering project is analyzed and discussed by this method; moreover, the system reliability index β is calculated as well. These analysis results are helpful to provide scientific basis for structural optimization, structural testing, and structural reinforcement and so on.

scholarly journals Failure of Rock Slope with Heterogeneous Locked Patches: Insights from Numerical Modelling

2021 ◽  
Vol 11 (18) ◽  
pp. 8585
Author(s):  
Bin Fu ◽  
Yingchun Li ◽  
Chun’an Tang ◽  
Zhibin Lin
Keyword(s):  
Slope Stability ◽  
Failure Mode ◽  
Rock Slope ◽  
Failure Modes ◽  
Process Analysis ◽  
Failure Process ◽  
Shear Loading ◽  
Constitutive Relationship ◽  
Rock Slope Stability ◽  
Geometrical Properties

Rock slope stability is commonly dominated by locked patches along a potential slip surface. How naturally heterogeneous locked patches of different properties affect the rock slope stability remains enigmatic. Here, we simulate a rock slope with two locked patches subjected to shear loading through a self-developed software, rock failure process analysis (RFPA). In the finite element method (FEM)-based code, the inherent heterogeneity of rock is quantified by the classic Weibull distribution, and the constitutive relationship of the meso-scale element is formulated by the statistical damage theory. The effects of mechanical and geometrical properties of the locked patches on the stability of the simulated rock slope are systematically studied. We find that the rock homogeneity modulates the failure mode of the rock slope. As the homogeneity degree is elevated, the failure of the locked patch transits from the locked patch itself to both the interfaces between the locked patched and the slide body and the bedrock, and then to the bedrock. The analysis of variance shows that length and strength of locked patch affect most shear strength and the peak shear displacement of the rock slope. Most of the rock slopes exhibit similar failure modes where the macroscopic cracks mainly concentrate on the interfaces between the locked patch and the bedrock and the slide body, respectively, and the acoustic events become intensive after one of the locked patches is damaged. The locked patches are failed sequentially, and the sequence is apparently affected by their relative positions. The numerically reproduced failure mode of the rock slope with locked patches of different geometrical and mechanical properties are consistent with the laboratory observations. We also propose a simple spring-slider model to elucidate the failure process of the rock slope with locked patches.

Modeling of the Effect of Excavation Mode on the Extent of the Anisotropic Zone Surrounding Deep Tunnels

2007 ◽  
Vol 353-358 ◽  
pp. 3014-3017
Author(s):  
Shu Hong Wang ◽  
Juan Xia Zhang ◽  
Chun An Tang ◽  
Shan Yong Wang
Keyword(s):  
Numerical Model ◽  
Failure Modes ◽  
Deep Level ◽  
Process Analysis ◽  
Failure Process ◽  
Side Wall ◽  
Damage Threshold ◽  
Great Depth ◽  
Anisotropic Rock ◽  
Rock Tunnels

A series of numerical model tests were performed to investigate the behaviour of the anisotropic rock surrounding circular excavations under high confining pressures. The aim was to provide information on the formation of fractures and failure around deep level rock tunnels under controlled conditions. Solid cubes containing a circular hole were confined to a vertical pressure with same as the confinement in the horizontal directions. In this modeling, the inhomogeneous rock is generated by using Weibull parameters which are related to the microstructural properties determined by crack size distribution and grain size. The fracture angle is assumed to be 45o. The observed failure zone around the excavation was simulated using both the maximum tensile strain criterion and Mohr-Coulomb criterion respectively (as the damage threshold). And RFPA (Realistic Failure Process Analysis) code was used as the calculating tool in this modelling, three opening modes are simulated and compared. Computational model predictions that include crack propagation and failure modes of rock show a good agreement with those of the observation in site. It is pointed out that the damage evolution of EDZ strongly depends on the inhomogeneous, the excavation mode, anisotropic property, and the various loading conditions. Concerning the existence of a weak plane, the amount of displacement at the side wall of the tunnel was quite large, since the shear deformation occurred in EDZ. The model is implemented in RFPA code and is able to represent the change in fracture patterns between the solid and jointed parts. This provides confidence for the application of the numerical model to the design of rock tunnels at great depth.

Numerical Simulation on Failure Process of Concrete-Filled Rectangular Steel Tube Column

2009 ◽  
Vol 417-418 ◽  
pp. 365-368
Author(s):  
Guang Ping Zou ◽  
Pei Xiu Xia ◽  
Xue Dong Zhang
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Bearing Capacity ◽  
Development Process ◽  
Process Analysis ◽  
Failure Process ◽  
Steel Tube ◽  
Ultimate Bearing Capacity ◽  
Axial Loads ◽  
Simulation Results

Realistic Failure Process Analysis (RFPA3D) was used to simulate the concrete-filled rectangular steel tube columns which are subjected to axial loads. The ultimate bearing capacity and the load-strain figures were presented. The Numerical simulation results were verified by experimental data of the paper [5]. Meanwhile, the development process of crack in the specimen was described. The whole failure process of rectangular steel tube columns was reproduced. The failure principles of concrete-filled rectangular steel tube column were discussed deeply.

Avalanche Behaviour in Microfracturing Process of 3-D Brittle Disordered Material

2005 ◽  
Vol 297-300 ◽  
pp. 2567-2572 ◽  
Author(s):  
De Shen Zhao ◽  
Tao Xu ◽  
Chun An Tang ◽  
Hou Quan Zhang ◽  
Zheng Zhao Liang
Keyword(s):  
Uniaxial Compression ◽  
Crack Nucleation ◽  
Process Analysis ◽  
Failure Process ◽  
Acoustic Emissions ◽  
Peak Stress ◽  
Disordered Materials ◽  
Avalanche Behavior ◽  
Fracturing Process

Using a newly-developed Material Failure Process Analysis code (MFPA3D), the micro-fracturing process and the avalanche behavior characterization of brittle disordered materials such as rock or concrete is numerically studied under uniaxial compression and tension. It is found that, due to the heterogeneity of the disordered material, there is an avalanche behavior in the microcrack coalescence process. Meanwhile, a hierarchy of avalanche events also numerically observed though a study of numerically obtained acoustic emissions or seismic events. Numerical simulations indicate that macro-crack nucleation starts well before the peak stress is reached and the crack propagation and coalescence can be traced, which can be taken as a precursory to predict the macro-fracture of the brittle disordered materials. In addition, the numerically obtained results also reveal the presence of residual strength in the post-peak region and the resemblance in the stress-strain curves between uniaxial compression and tension.

Failure characterization of PLA parts fabricated by fused deposition modeling using acoustic emission

2020 ◽  
Vol 26 (7) ◽  
pp. 1177-1182
Author(s):  
Feng Li ◽  
Zhonghua Yu ◽  
Zhensheng Yang
Keyword(s):  
Acoustic Emission ◽  
Fused Deposition Modeling ◽  
Failure Modes ◽  
Failure Process ◽  
Acoustic Emissions ◽  
Peak Frequency ◽  
Monitoring Method ◽  
Content Type ◽  
Fused Deposition ◽  
Deposition Modeling

Purpose This paper aims to focus on investigating the failure mode of fused deposition modeling (FDM) fabricated parts by using acoustic emission (AE) technique. Design/methodology/approach Considering the special prototyping way of FDM, the failure modes of FDM-fabricated parts were investigated experimentally. One test was carried out and the other two describe what has been observed on this basis. Acoustic emissions are obtained during the tensile process. AE features of peak frequency, energy and amplitude are extracted and preliminarily analyzed. Then, the unsupervised clustering method of k-means is applied to explore the relationship between the failure modes and the AE signals. Findings Failure modes of filament debonding and breakage can be successfully recognized by the pattern recognition technique of k-means. Practical implications The results obtained can help us understand the failure process of FDM printed parts. This will provide an available monitoring method in the application of FDM-fabricated parts. Originality/value This paper has investigated and characterized the failure modes of FDM fabricated parts for the first time.

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