Experimental Research on Strength Characteristics of Bulky Rock Material with Different Coarse Grain Content in Waste Pile of Mine

2012 ◽  
Vol 170-173 ◽  
pp. 295-300 ◽  
Author(s):  
Jun Du ◽  
Ke Peng Hou ◽  
Wei Liang
Keyword(s):  
Shear Modulus ◽  
Normal Stress ◽  
Friction Angle ◽  
Rock Material ◽  
Shear Displacement ◽  
Coarse Grain ◽  
Horizontal Loading ◽  
Shear Process ◽  
Main Basis ◽  
Rock And Soil

Bulky rock material of waste pile was composed of discarded rock and soil which was blasted and stripped from stope. It was characterized by dispersibility, complexity and variability. Shear strength index of bulky rock material was the main basis for analyzing slope stability of the waste pile. After the study on bulky rock material with different coarse grain content by indoor direct shear test, the results indicated that there was no obvious peak strength during the shear process, and variation of the shear displacement was slight in initial horizontal loading stage. Horizontal loading increased slowly and shear displacement had obvious change when shear displacement exceeded 5mm. Under the same normal stress, shear modulus G0.01 increased with the increase of coarse grain content when shear strain of specimen is 1/100. Shear modulus G0.01 of the specimen with same coarse grain content increased with the increase of normal stress, varying sensitive of G0.01 reduced when coarse grain content was larger. When the specimens with same coarse grain content were under failure, the shear modulus Gfailure was smaller than G0.01. Cohesive force c of the bulky rock material began to increase and then decrease with the increase of coarse grain content, and reached its maximum of 31.25KPa when the coarse grain content was 70%, internal friction angle increased with the increase of coarse grain content.

Effect of Grain Orientation Distribution on Anisotropy of Idealized Granular Materials

2012 ◽  
Vol 174-177 ◽  
pp. 24-29
Author(s):  
Bo Zhou ◽  
Ji Wei Li ◽  
Peng Shuai
Keyword(s):  
Granular Materials ◽  
Grain Orientation ◽  
Volumetric Strain ◽  
Friction Angle ◽  
Orientation Distribution ◽  
Biaxial Compression ◽  
Shape Effect ◽  
Vertical Loading ◽  
Horizontal Loading ◽  
Long Rod

Abstract. The regular grain orientation of granular materials is a common phenomenon in nature. Based on the research of grain shape effect on mechanical property of granular materials, two kinds of idealized shape grain (kind of long rod and square) assemblies with different grain orientation were studied by simulated biaxial compression test using Discrete Element Method. The significant orientation which can be computed as the mean value of all grain orientation is introduced to represent the orientation regularity of granular materials. In order to study the anisotropy, the mobilized friction angle and volumetric strain of assemblies with different significant orientation were obtained under both vertical and horizontal loading. The results show that the regular orientation of grains influences the movement such as motion and rotation obviously; with the increasing of significant orientation, peak mobilized friction angle of long rod grain assembly gradually increases under horizontal loading, and decreasing under vertical loading.

An experimental method for the investigation of rigid polyurethane foams in shear

2018 ◽  
Vol 54 (5) ◽  
pp. 851-884
Author(s):  
Ilze Beverte
Keyword(s):  
Shear Modulus ◽  
Polyurethane Foams ◽  
Shear Displacement ◽  
Test Material ◽  
Experimental Investigations ◽  
Plastic Foams ◽  
Tension Tests ◽  
Different Dimensions ◽  
Porous Plastic

Widespread applications of rigid polyurethane and plastic foams lead to shear deformations. Therefore, methods for ensuring shear using experimental investigations are necessary, including the possibility of determining the shear modulus, strength and limit angle. Therefore, a device that allows investigating the shear properties of highly porous plastic foams was developed. The proposed device comprises a clip-on extensometer, commonly exploited in uni-axial compression/tension tests, for the determination of the shear displacement directly on the foams’ sample, on a measurement zone of certain dimensions and location. An innovative construction of the extensometer’s legs is elaborated, permitting to investigate the shear displacement field for different dimensions of the measurement zone. Precision of the device is examined by performing a penetration test on materials of different densities: (a) polyurethane foams and (b) wood. Technology for the production of isotropic polyurethane foams as a test material is described in detail. Experimental determination of shear modulus and strength of one and the same sample, in one and the same experiment is elaborated. Displacements in different zones of sample’s work beam are investigated. Experimental data are compared with the results of mathematical modelling and a good correlation is proved to exist.

Ecological Highway Slope Stability Analysis by Inversion Method

2011 ◽  
Vol 250-253 ◽  
pp. 2161-2166
Author(s):  
Jun Zhao Gao ◽  
Guo Feng Xiao ◽  
Hai Qiang Miao
Keyword(s):  
Slope Stability ◽  
Soil Mechanics ◽  
Friction Angle ◽  
Inversion Method ◽  
Time Inversion ◽  
Long Time ◽  
Main Factors ◽  
Reinforcement Design ◽  
Rock And Soil

Side slop losing stability is one of the main factors which greatly influences freeway expedite construction, especially after side slop losing stability the determination of rock and soil mechanics parameter may take a long time. Inversion method to analyze slope stability can preferably solve the problem. During the treatment of the ecological freeway landslide, we can not obtain important Parameters due to great disparity of sample Parameters of landslide. However, using inversion method to get cohesion and internal friction Angle, and anglicizing its sensitivity during calculation of stability can identify reliable Parameters. According to slope stability calculus, the ecological reinforcement design scheme come into effect.

scholarly journals Shear Mechanical Behaviours and Multistrength Parameter Characteristics of Fault Gouge

2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Han Bao ◽  
Qun Qi ◽  
Hengxing Lan ◽  
Changgen Yan ◽  
Wei Xu ◽  
...  
Keyword(s):  
Water Content ◽  
Normal Stress ◽  
Clay Minerals ◽  
Residual Strength ◽  
Failure Modes ◽  
Friction Angle ◽  
Strength Properties ◽  
Fault Gouge ◽  
Normal Stresses ◽  
Fault Gouges

Fault gouge has special mechanical properties and remarkable engineering effects. Using a ring shear test, the strength properties of the differently colored remolded fault gouges of the Shendaogou Fault in Yan’an were studied by changing moisture contents and normal stresses. Chlorite and illite are the main clay minerals in fault gouges; differences in mineral composition make fault gouges appear in different colors. Besides clay minerals, the dried fault gouges disintegration in water is also due to the transformation of gypsum. The gradation of green fault gouge and multicolor fault gouge is better than that of the red fault gouge, while the fault gouges’ strain softening properties become weaker as the coarse grain content increases. Affected by water content and normal stress, the shear planes can be divided into three failure modes: peeling failure, grooved failure, and sliding failure. With the increase of water content, there will be a significant weakening on cohesion and friction angle. A new parameter, the “Normal Stress Threshold (NST),” is introduced as a critical value for the emergence of the strain hardening phenomenon, and the NSTs of different fault gouges are significantly different. The functions obtained from the relation of residual strength, peak strength, and normal stress can be used to calculate shear strength parameters under any normal stresses. In addition, the residual strength of fault gouge is obviously different from clay and loess, which can be qualitatively explained by clay particle contents.

An Analysis on Influencing Factors of Interlayer Separation of Complex Roof in Deep Coal Mining

2010 ◽  
Vol 146-147 ◽  
pp. 976-979
Author(s):  
De Yi Wu ◽  
Ai Lang Wang ◽  
Hua Qiang Liang
Keyword(s):  
Numerical Simulation ◽  
Normal Stress ◽  
Coal Mining ◽  
Influencing Factors ◽  
Friction Angle ◽  
Rock Stress ◽  
Roof Collapse ◽  
Tunnel Width ◽  
Original Rock

In order to control construction face instability of complex roof and predict roof collapse in deep coal mining, by numerical simulation, distribution of normal stress and interlayer separation of construction surface were calculated and influencing factors on separation of construction surface were analyzed in different conditions. The conclusions were drawn that original rock stress, rock characters, rock thickness and tunnel width had obvious influence and cohesion and friction angle of construction surface had little influence on separation of construction surface.

Moisture Dependent Dynamic Flow Properties of Coconut Flours

2016 ◽  
Vol 12 (6) ◽  
pp. 577-585 ◽  
Author(s):  
M. R. Manikantan ◽  
R. P. Kingsly Ambrose ◽  
Sajid Alavi
Keyword(s):  
Moisture Content ◽  
Normal Stress ◽  
Flow Characteristics ◽  
Coconut Oil ◽  
Friction Angle ◽  
Wall Friction ◽  
Flow Properties ◽  
Dynamic Flow ◽  
Virgin Coconut Oil ◽  
Air Velocity

Abstract The dynamic flow properties of two important coproducts of virgin coconut oil (VCO) i. e. coconut milk residue flour (MRF) and VCO cake flour (CF) were studied. The basic flowability energy of CF was higher than MRF and increased with moisture content. The change in compressibility and shear stress, with applied normal stress and moisture content, indicated that these powders are highly cohesive. For both flours, the energy required to make the powder flow increased with moisture at all experimental air velocity. Moisture did not significantly influence the cohesion and unconfined yield strength of MRF, whereas for CF there was significant effect due to the presence of moisture. The wall friction angle of both the flours increased significantly with moisture and decreased with applied normal stress. The results from this study indicated that, both CF and MRF at around 4.00 % moisture content had better flow characteristics than at higher moisture levels.

scholarly journals Permeability Evolution of an Intact Marble Core during Shearing under High Fluid Pressure

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-18
Author(s):  
Yuan Wang ◽  
Yu Jiao ◽  
Shaobin Hu
Keyword(s):  
Normal Stress ◽  
Laser Scanning ◽  
Shear Failure ◽  
Fluid Pressure ◽  
Shear Displacement ◽  
Permeability Evolution ◽  
Fracture Permeability ◽  
Effective Normal Stress ◽  
High Fluid ◽  
High Fluid Pressure

The progressive shear failure of a rock mass under hydromechanical coupling is a key aspect of the long-term stability of deeply buried, high fluid pressure diversion tunnels. In this study, we use experimental and numerical analysis to quantify the permeability variations that occur in an intact marble sample as it evolves from shear failure to shear slip under different confining pressures and fluid pressures. The experimental results reveal that at low effective normal stress, the fracture permeability is positively correlated with the shear displacement. The permeability is lower at higher effective normal stress and exhibits an episodic change with increasing shear displacement. After establishing a numerical model based on the point cloud data generated by the three-dimensional (3D) laser scanning of the fracture surfaces, we found that there are some contact areas that block the percolation channels under high effective stress conditions. This type of contact area plays a key role in determining the evolution of the fracture permeability in a given rock sample.

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