scholarly journals Estimation of the Poisson’s Rate of the Intact Rock in the Function of the Rigidity

2019 ◽  
Author(s):  
Benedek A. Lógó ◽  
Balázs Vásárhelyi
Keyword(s):  
Poisson’S Ratio ◽  
Experimental Error ◽  
Limit Equilibrium ◽  
Material Constant ◽  
Friction Angle ◽  
Intact Rock ◽  
Poisson's Ratio ◽  
Mechanical Parameters ◽  
Linear Elastic ◽  
Rock Types

Although Poisson’s ratio is one of the basic rock mechanical parameters, it is less investigated than the other parameters. It can be assumed, that this material constant depends on the rigidity of the rock, among the others. The goal of this research is to find a theoretical relationship between the rigidity of the intact rock and Poisson’s ratio. It was assumed that there is a connection between the internal friction angle (or cohesion) and rigidity of the isotropic, linear elastic material, using the Mohr-Coulomb theory. Based on these equations from different published limit equilibrium, six different equations were compared. It is published that the rigidity value is equal (within the experimental error) to the Hoek-Brown material constant (mi) which value is well-known for many different rock types. Plotting the published Poisson’s ratio in the function of the rigidity of the intact rock the optimal connection was chosen.

scholarly journals Complex analysis of uniaxial compressive tests of the Mórágy granitic rock formation (Hungary)

2019 ◽  
Vol 41 (1) ◽  
pp. 21-32 ◽  
Author(s):  
M. Davarpanah ◽  
G. Somodi ◽  
L. Kovács ◽  
B. Vásárhelyi
Keyword(s):  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Granitic Rock ◽  
Young's Modulus ◽  
Intact Rock ◽  
Poisson's Ratio ◽  
Mechanical Parameters ◽  
Modulus Ratio ◽  
Rock Samples ◽  
Compressive Tests

AbstractUnderstanding the quality of intact rock is one of the most important parts of any engineering projects in the field of rock mechanics. The expression of correlations between the engineering properties of intact rock has always been the scope of experimental research, driven by the need to depict the actual behaviour of rock and to calculate most accurately the design parameters. To determine the behaviour of intact rock, the value of important mechanical parameters such as Young’s modulus (E), Poisson’s ratio (ν) and the strength of rock (σcd) was calculated. Recently, for modelling the behaviour of intact rock, the crack initiation stress (σci) is another important parameter, together with the strain (σ). The ratio of Young’s modulus and the strength of rock is the modulus ratio (MR), which can be used for calculations. These parameters are extensively used in rock engineering when the deformation of different structural elements of underground storage, caverns, tunnels or mining opening must be computed. The objective of this paper is to investigate the relationship between these parameters for Hungarian granitic rock samples. To achieve this goal, the modulus ratio (MR = E/σc) of 50 granitic rocks collected from Bátaapáti radioactive waste repository was examined. Fifty high-precision uniaxial compressive tests were conducted on strong (σc >100 MPa) rock samples, exhibiting the wide range of elastic modulus (E = 57.425–88.937 GPa), uniaxial compressive strength (σc = 133.34–213.04 MPa) and Poisson’s ratio (ν = 0.18–0.32). The observed value (MR = 326–597) and mean value of MR = 439.4 are compared with the results of similar previous researches. Moreover, the statistical analysis for all studied rocks was performed and the relationshipbetween MR and other mechanical parameters such as maximum axial strain $\left( {{\varepsilon }_{\text{a,}\,\text{max}}} \right)$for studied rocks was discussed.

The Model for Calculating Elastic Modulus and Poisson's Ratio of Coal Body

2013 ◽  
Vol 6 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Ai Chi ◽  
Li Yuwei
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Fractured Rock ◽  
Rock Block ◽  
Poisson's Ratio ◽  
Linear Elastic ◽  
Study Results ◽  
The Face ◽  
Block Face ◽  
Coal Rock

Coal body is a type of fractured rock mass in which lots of cleat fractures developed. Its mechanical properties vary with the parametric variation of coal rock block, face cleat and butt cleat. Based on the linear elastic theory and displacement equivalent principle and simplifying the face cleat and butt cleat as multi-bank penetrating and intermittent cracks, the model was established to calculate the elastic modulus and Poisson's ratio of coal body combined with cleat. By analyzing the model, it also obtained the influence of the parameter variation of coal rock block, face cleat and butt cleat on the elastic modulus and Poisson's ratio of the coal body. Study results showed that the connectivity rate of butt cleat and the distance between face cleats had a weak influence on elastic modulus of coal body. When the inclination of face cleat was 90°, the elastic modulus of coal body reached the maximal value and it equaled to the elastic modulus of coal rock block. When the inclination of face cleat was 0°, the elastic modulus of coal body was exclusively dependent on the elastic modulus of coal rock block, the normal stiffness of face cleat and the distance between them. When the distance between butt cleats or the connectivity rate of butt cleat was fixed, the Poisson's ratio of the coal body initially increased and then decreased with increasing of the face cleat inclination.

scholarly journals The effect of saturation on the physical and mechanical behavior of some rock samples

2021 ◽  
Vol 2 (3) ◽  
pp. 23-31
Author(s):  
Mohammad Taghi Hamzaban
Keyword(s):  
Tensile Strength ◽  
Mechanical Behavior ◽  
Physical And Mechanical Properties ◽  
Intact Rock ◽  
P Wave ◽  
Mechanical Parameters ◽  
Brazilian Tensile Strength ◽  
Rock Samples ◽  
Rock Types ◽  
Major Factors

Different major factors control the strength of solid rocks. Moisture content is one of the most important factors, which can change the physical and mechanical behavior of intact rock as well as rock mass. Several early studies have shown that rock is weaker if tested wet rather than dry. In this paper, the density, P-wave velocity, uniaxial compressive strength, Brazilian tensile strength, and modulus of elasticity of seven different intact rock samples were measured under both dry and saturated conditions. The porosity of the samples was reported as well. Based on the obtained results, some correlations were proposed for estimating the saturated physical and mechanical properties from dry ones. The proposed correlations include different rock types and are more general than the previously reported ones. Comparing the obtained results showed that the mechanical and physical properties of weaker samples are more sensitive to the saturation process. Moreover, among the different mechanical parameters, Brazilian tensile strength exhibited more sensitivity to saturation. Comparing the results with the calculated porosities revealed that porosity is one of the key factors in the effect of saturation on physical and mechanical parameters. It seems that in the more porous rock samples, greater changes in the different measured parameters occur after saturation.

scholarly journals PPV Criterion of a Rock Slope Imbedded with a Fault subjected to Blasting P-Waves

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Shiwei Lu ◽  
Chuanbo Zhou ◽  
Zhen Zhang ◽  
Ling Ji ◽  
Nan Jiang
Keyword(s):  
Slope Stability ◽  
Young’S Modulus ◽  
Poisson’S Ratio ◽  
Rock Slope ◽  
Young's Modulus ◽  
Intact Rock ◽  
P Wave ◽  
Poisson's Ratio ◽  
Rock Slopes ◽  
Near Surface

The open-pit mining slopes continue to become higher and steeper with the continuous exploitation of near-surface mineral resources. The blasting excavation exerts a significance influence on the slope stability. In fact, intact rock slopes do not exist and slope stability is controlled by the geological defects. In this paper, the stability of a rock slope imbedded with a fault is considered. The P-wave component of blasting seismic waves is focused on and the fault is simplified as a semi-infinite crack. In background of Daye iron mine, the peak particle velocity (PPV) threshold is determined based on the linear elastic fracture dynamics. The influence of frequency, Young's modulus, and Poisson's ratio is studied to modify the PPV threshold. Results show that (1) the PPV threshold decreases with the increasing Young's modulus and Poisson's ratio, but increases with the increasing frequency; (2) the initiation angle is immune to Young's modulus and the frequency, and only depends on the Poisson's ratio; (3) the PPV criterion is finally determined as 1.47 cm/s when the frequency f ≤ 10 Hz, 1.47 cm/s–3.30 cm/s when 10 Hz < f ≤ 50 Hz and 3.37 cm/s–6.59 cm/s when f > 50 Hz, which are far less than that of intact rock slopes; (4) The north slope is quite safe if the proposed PPV threshold is not violated due to the variation range of the initiation angle θ0.

Study on the Development of Plastic Zone Based on Strain Expressed Mohr- Coulomb Yield Condition

2014 ◽  
Vol 580-583 ◽  
pp. 195-200
Author(s):  
Cai Yang ◽  
Tu Gen Feng
Keyword(s):  
Internal Friction ◽  
Plastic Zone ◽  
Poisson’S Ratio ◽  
Yield Condition ◽  
Friction Angle ◽  
Strength Reduction ◽  
Internal Friction Angle ◽  
Slope Instability ◽  
Poisson's Ratio ◽  
Material Parameters

At present, there is a lot of research for slope stability, the inherent reason of slope instability is geotechnical material will get plastic deformation under load. In this paper, Mohr- Coulomb yield condition is transformed strain expressed to stress expressed.Based on this, analysis the effects that geotechnical material parameters internal friction angle ,cohesion c and Poisson's ratio to Mohr- Coulomb yield condition and the development of soil plastic zone.In addition, using the strength reduction FEM simulating the change of plastic zone distribution caused by change of the geotechnical materials parameters .The results show that the internal friction angle , cohesion c are reducted, the plastic zone expand;Increasing the Poisson’s ratio , narrowing the slope’s plastic zone;Plastic zone’s different distribution is caused by different material parameters affect the yield surface.

scholarly journals A modified bond model for describing isotropic linear elastic material behaviour with the discrete element method

2021 ◽  
Author(s):  
Rahav Gowtham Venkateswaran ◽  
Ursula Kowalsky ◽  
Dieter Dinkler
Keyword(s):  
Discrete Element Method ◽  
Elastic Material ◽  
Poisson’S Ratio ◽  
Strain Energy ◽  
Discrete Element ◽  
Poisson's Ratio ◽  
Linear Elastic Material ◽  
Linear Elastic ◽  
Bond Model ◽  
Element Method

AbstractRecently, the discrete element method is increasingly being used for describing the behaviour of isotropic linear elastic materials. However, the common bond models employed to describe the interaction between particles restrict the range of Poisson’s ratio that can be represented. In this paper, to overcome the restriction, a modified bond model that includes the coupling of shear strain energy of neighbouring bonds is proposed. The coupling is described by a multi-bond term that enables the model to distinguish between shear deformations and rigid-body rotations. The positive definiteness of the strain energy function of the modified bond model is verified. To validate the model, uniaxial tension, pure shear and pure bending tests are performed. Comparison of the particle displacements with continuum mechanics solution demonstrates the ability of the model to describe the behaviour of isotropic linear elastic material for values of Poisson’s ratio in the range $$0 \le \nu < 0.5$$ 0 ≤ ν < 0.5 .

scholarly journals Numerical Investigation of Stress Distributions in Stope Backfills

2018 ◽  
Author(s):  
Qingyang Yu ◽  
Xiangli Chen ◽  
Zhenxue Dai ◽  
Lei Nie ◽  
Mohamad Reza Soltanian
Keyword(s):  
Stress Distribution ◽  
Aspect Ratio ◽  
Internal Friction ◽  
Poisson’S Ratio ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Abandoned Mines ◽  
Poisson's Ratio ◽  
Ground Subsidence ◽  
Stress Distributions

Stope backfill is important in avoiding mine collapse during and after extraction phases, ground subsidence in abandoned mines, and environmental damages. The stress distribution is one of the key factors in designing stope backfills. In this paper, we perform a numerical modeling study to investigate the stress distribution within and around the stope backfill. Importantly, our simulation results are in agreement with Marston’s (1930) plain-strain arching theory. The results show that the stress arch is critical in stope backfills. The potential effects of internal friction angle, aspect ratio, and Poisson’s ratio on stress distributions are also analyzed. The stress decreases when the aspect ratio, internal friction angle, and Poisson’s ratio increase. Our results suggest that decreasing the aspect ratio and choosing materials with a high internal friction angle and Poisson’s ratio are important for designing the stope backfill. The cohesive force index and elastic modulus also have significant effects on the stress distribution. Our findings have practical implications in designing stope backfills.

scholarly journals Differences of Mechanical Parameters and Rockburst Tendency Indices between Coal and Non-Coal Rocks and Modified Rockburst Tendency Classification Criteria for Non-Coal Rocks

2021 ◽  
Vol 11 (6) ◽  
pp. 2641
Author(s):  
Kun Du ◽  
Yu Sun ◽  
Songge Yang ◽  
Shizhan Lv ◽  
Shaofeng Wang
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Dynamic Fracture ◽  
Poisson’S Ratio ◽  
Elastic Strain Energy ◽  
Classification Criteria ◽  
Poisson's Ratio ◽  
Uniaxial Tensile ◽  
Mechanical Parameters ◽  
Energy Index

Rockbursts represent hazardous dynamic disasters for underground coal mines and other underground rock engineering projects. Some bursting liability indices are put forward and applied to identify the likelihood of rock burst occurrence. The classification criteria of the bursting liability indices are proved to be reasonable for coals, but they are still immature for non-coal rocks. Thus, it is uncertain that it is reasonable to use the classification criteria of coal for evaluating the bursting liability of non-coal rocks. Hence, in this study, a large amount of data, such as the basic mechanical parameters, i.e., Poisson’s ratio μ, elastic modulus E, uniaxial compressive strength σc, and uniaxial tensile strength σt, and the bursting liability indices, i.e., elastic strain energy index WET, bursting energy index Wcf, dynamic fracture duration time DT, and brittleness index B, of different coals and non-coal rocks were collected in China. Then, the differences of mechanical parameters and rockburst tendency indices between coal and non-coal rocks were studied systematically, and apart from the Poisson’s ratio μ, the other three basic mechanical parameters of coal and non-coal rocks have great differences in data distribution and concentration scope, which proved that the non-coal rocks cannot share the same index system and classification criteria of coals. In addition, the evaluation results of a single index for rock bursting liability of rocks were directly compared in pairs, and the inconsistency rate for coals is about 42–68%. It is necessary to build a comprehensive evaluation method to evaluate the bursting liability of rocks. At last, the modified rockburst tendency classification criteria for non-coal rocks were put forward. It is reasonable to use the classification criteria of the WET and Wcf to classify the bursting liability of non-coal rocks, while it is unreasonable to use that of the DT and σc. It has been concluded that the index B are more suitable for non-coal rocks, and a new index, named strength decrease rate (SDR), was proposed to determine the bursting liability, which is the ratio of uniaxial compressive strength σc to duration of dynamic fracture DT.

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