scholarly journals Experimental Investigation on the Influence of Water Content on the Mechanical Properties of Coal under Conventional Triaxial Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Meichang Zhang ◽  
Rongshan Nie
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Conventional Triaxial Compression ◽  
Influence Of Water ◽  
Confining Pressures ◽  
Water Contents

The presence of water is one of the most important factors in coal mining, and it has a dual influence on the mechanical behavior of rock. To study the influence of water content on the mechanical properties of coal under complicated stress conditions, dry coal specimens and wet coal specimens with water contents of 1.8% and 3.6% were conducted by uniaxial and conventional triaxial compression tests. The relations between the uniaxial compressive strength, deformation, and water content were observed. The reductions in the strength and elastic modulus under different confining pressures were obtained. The mechanical properties of coal specimens with different water contents under triaxial compression were studied. The influences of water content on the microstructure, clay minerals, internal friction angle, and cohesive force of coal were discussed. The results show that the strengths and elastic moduli of wet specimens are clearly lower than those of dry specimens under different confining pressures. The water content has a significant influence on the postfailure mechanical behavior of coal. The loss rates of strength and elastic modulus decrease with increasing confining pressure. The water content has almost no effect on the internal friction angle, while the cohesive force of the saturated specimens is 36.5% lower than that of the dry specimens. The results can provide a reference for inhibiting the occurrence of disasters during coal mining and exploiting coal efficiently.

Influence of Water Contents on Shear Strength of Rammed Earth Wall of Earth-Building

2011 ◽  
Vol 382 ◽  
pp. 172-175
Author(s):  
Ren Wei Wu ◽  
Xing Qian Peng ◽  
Li Zhang
Keyword(s):  
Shear Strength ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
World Heritage Site ◽  
Rammed Earth ◽  
Compression Tests ◽  
Rammed Earth Wall ◽  
Influence Of Water ◽  
Water Contents

As the "Fujian earth-building" have been inscribed by UNESCO in 2008 as World Heritage Site, attentions of protection about the "Fujian earth-building" has getting more and more. This article takes samples of a rammed-earth wall from Yongding earth-buildings and determines the shear strength of the samples with different water content through triaxial compression tests. The influence on shear strength of water content of rammed-earth samples is analyzed. Test results show that the shear strength of rammed-earth has much to do with the water content of the soil, the greater the water content is，the smaller the shear strength is. With water content increasing, cohesion and internal friction angle of rammed-earth were decreases, and its changing trend is of marked characteristic of stage. When water contents of rammed-earth is under some value, its cohesion changes in small ranges; when water contents of rammed-earth is over the value, its cohesion decreases with water content increasing.

Experimental Study on the Influence of Temperature on Shale Mechanical Properties under Conventional Triaxial Compression

2011 ◽  
Vol 250-253 ◽  
pp. 1452-1455 ◽  
Author(s):  
Lu Bo Meng ◽  
Tian Bin Li ◽  
Liang Wen Jiang ◽  
Hong Min Ma
Keyword(s):  
Mechanical Properties ◽  
Thermal Stress ◽  
Elastic Modulus ◽  
High Temperature ◽  
Poisson’S Ratio ◽  
Triaxial Compression ◽  
Poisson's Ratio ◽  
Influence Of Temperature ◽  
Conventional Triaxial Compression ◽  
Influence Of Temperature On

High temperature conventional triaxial compression test of shale are carried out by the MTS815 servo-controlled testing machine, based on the experimental results, the relationships between temperature and shale peak strength, elastic modulus, Poisson's ratio, cohesion, internal friction angle are investigated. Although the experimental results are discrete comparatively, the general law is obvious. When the confining pressure imposed on shale is constant and the temperature changes form 25°C to 120°C, with the increasing of the temperature, the triaxial compression strength, shear strength gradually increase, while average elastic modulus, Poisson's ratio has a slightly decrease. The thermal stress generated by the high temperature plays a role to accommodate the deformation and the function of preventing crack propagation, thus the bearing capacity of shale samples are strengthened. But the influence of temperature on shale mechanical properties mutates when the temperature is at 80°C. Shale peak strength dramatically decreased, average elastic modulus decreased slightly, and Poisson's ratio also increased slightly, which indicated that at 80°C, different thermal expansivity of mineral particles of shale may cause cross-grain boundary thermal expansion incongruous, creating additional thermal stress, thus the sample’s bearing capacity decreased.

An Experimental Study on the Mechanical Properties of Soils of the Landslide Induced by Rainfall

2011 ◽  
Vol 90-93 ◽  
pp. 1303-1306
Author(s):  
Dong Heng Hao ◽  
Jian Feng Qi ◽  
Bin Wang ◽  
Shu Qin Zhao
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Internal Friction ◽  
Water Content ◽  
Strain Softening ◽  
Friction Angle ◽  
Mechanical Parameters ◽  
Strain Stress ◽  
Geotechnical Tests ◽  
Sliding Zone

Geotechnical tests are performed to study the strain-stress behavior and mechanical parameters by using the automatic KTG triaxial shear apparatus. This study shows that the strain softening phenomenon emerges after the peak values of strain-stress relations appear for the sliding-body soils, and that the strain-stress relations are in the sate of strain hardening all the time for the sliding-zone soils although the water content keeps sameness. The variation laws of cohesion and internal friction angle with water content are respectively consistent with an exponential function and linear relation.

Gravel Content Effect on the Shear Strength of Clay-Gravel Mixtures

2011 ◽  
Vol 71-78 ◽  
pp. 4685-4688 ◽  
Author(s):  
Chen Wang ◽  
Chuan Ni Zhan
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Triaxial Compression ◽  
Constant Strain Rate ◽  
Friction Angle ◽  
Confining Pressure ◽  
Internal Friction Angle ◽  
Compression Tests ◽  
Gravel Content ◽  
Confining Pressures

Gravel content is an important factor affecting the mechanical properties of clay-gravel mixtures. To study the effects of gravel content on the shear strength of clay-gravel mixtures, constant-strain-rate drained triaxial compression tests were conducted for various mixtures. The gravel contents were 30%, 40%, 50% and 70%. The confining pressures were varied from 50kPa to 300kPa. Test results indicate that the deviator stress at failure under the same confining pressure increases with the increase in gravel content. As the gravel content in the mixtures is between 30% and 50%, the shear strength is jointly attributed by clay and gravel. An increase in gravel content results in slight increases in both the cohesion intercept and internal friction angle. At gravel content of up to 70%, the shear strength of the mixture is controlled by that of the gravel, and the cohesion intercept and the internal friction angle increase sharply.

Stability Analysis of the Cutting Slope Considering the Influence of Water Content of Soil

2012 ◽  
Vol 204-208 ◽  
pp. 115-118 ◽  
Author(s):  
Qiang Ma ◽  
Heng Lin Xiao ◽  
Qi Zhi Hu ◽  
Li Hua Li
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Safety Factors ◽  
Strength Parameters ◽  
Direct Shear Tests ◽  
Cutting Slope ◽  
Influence Of Water ◽  
The Stability

Based on the method of strength reduction, numerical simulations were carried out to analyze the stability of the cutting slope. The direct shear tests of slope soil samples with different water content were carried out, and the safety factors of stability of the cutting slope were investigated with different cohesions and internal friction angles. At last, displacements and safety factors of stability of the slope with drains and without drains were calculated, and the observations of displacement of the cutting slope in field were also carried out. The results show that: The water content of the slope soil has great effects on the strength parameters, the cohesion and the internal friction angle decrease with the increase of the water content, and the effect is more significant on the cohesion than that on the internal friction angle. The safety factor of stability for the slope increases with the increase of the strength parameters, hence it increases with the decrease of the water content. The section of the slope without drains in the field is unstable, while the section with drains maintains stable.

scholarly journals Experimental Study on the Impact of Water Content on the Strength Parameters of Coral Gravelly Sand

2020 ◽  
Vol 8 (9) ◽  
pp. 634
Author(s):  
Yang Wu ◽  
Xing Wang ◽  
Jian-Hua Shen ◽  
Jie Cui ◽  
Chang-Qi Zhu ◽  
...  
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Particle Breakage ◽  
Internal Friction Angle ◽  
Capillary Water ◽  
Strength Parameters ◽  
Apparent Cohesion ◽  
The Impact

The effect of capillary water caused by heavy rainfall and groundwater level fluctuations can induce the erosion and collapse of island reef coral sand foundations. Here, the effects of water content (ω) on the shear strength parameters of coral gravelly sand are analyzed at the macro and micro scales by laboratory consolidated-drained triaxial compression and nuclear magnetic resonance tests. Furthermore, particle breakage characteristics of coral gravelly sand under the static load are discussed. With increasing ω, (1) the internal friction angle increases slightly (<1°) then decreases; (2) the apparent cohesion is more sensitive to the change in the ω; (3) with an increase from 5.4% to 21.3%, the bound water content remains almost unchanged; (4) the capillary water content is the main factor impacting the apparent cohesion; (5) the increase in free water content is the internal cause of the decreasing internal friction angle of coral gravelly sand with ω > 11.1%; and (6) the particle breakage increases, and there is an approximately linear relationship between the median particle diameter (d50) and relative breakage index (Br). The established physical model can reflect the influence of water content and plastic work and describe the evolution law of particle breakage.

Effect of Clay Dosage on Mechanical Properties of Plastic Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 664-667 ◽  
Author(s):  
Qiao Yan Guan ◽  
Peng Zhang
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Shear Strength ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Friction Angle ◽  
Splitting Tensile Strength ◽  
Plastic Concrete

A designed experimental study has been conducted to investigate the effect of clay dosage on mechanical properties of plastic concrete. The mechanical properties include compressive strength, splitting tensile strength, shear strength and elastic modulus. On the basis of the experimental results of the specimens of eight sets of mix proportions, the mechanism of action of clay on these mechanical properties has been analyzed in details. The results indicate that there is a tendency of decrease in the compressive strength, splitting tensile strength, shear strength and elastic modulus of plastic concrete with the increase of clay dosage. However, the internal friction angle of the shear specimens is increasing gradually with the increase of clay dosage. Further, the clay appears can improve the ductility of plastic concrete and this can help plastic concrete to bear larger deformation before failure.

Influence of Water Content on the Strength of Silt Soil in Yellow River Alluvial Plain

2012 ◽  
Vol 256-259 ◽  
pp. 481-487
Author(s):  
Xiao Ming Yi ◽  
Song Gen Wang ◽  
Zhen Qing Liu ◽  
Gang Xu
Keyword(s):  
Elastic Modulus ◽  
Water Content ◽  
Yellow River ◽  
Friction Angle ◽  
Cohesive Soil ◽  
High Water ◽  
Alluvial Plain ◽  
High Water Content ◽  
Optimum Water Content ◽  
Influence Of Water

Hydrophilic characteristic of silt soil in Yellow River alluvial plain was studied in order to reveal the water content changes of silt. Then strength tests were used to research how engineering parameters such as elastic modulus, cohesion and friction angle change at different water content. The results show that high permeability coefficient and strong capillary are main factors to increase the water content, and the influence of capillary rising is greater than that of rainfall infiltration. The strength characteristic of silt soil is similar to the character of non-cohesive soil in low water content and that of clay in high water content. If the water content is greater than optimum water content, the elastic modulus and cohesion of silt shall decay obviously. Friction angle decreases dramatically as well, when the soil is saturated.

Study on mechanical properties and damage evolution of carbonaceous shale under triaxial compression with acoustic emission

2021 ◽  
pp. 105678952199119
Author(s):  
Kai Yang ◽  
Qixiang Yan ◽  
Chuan Zhang ◽  
Wang Wu ◽  
Fei Wan
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Water Content ◽  
Damage Evolution ◽  
Damage Assessment ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Damage Variable ◽  
Natural State ◽  
Carbonaceous Shale

To explore the mechanical properties and damage evolution characteristics of carbonaceous shale with different confining pressures and water-bearing conditions, triaxial compression tests accompanied by simultaneous acoustic emission (AE) monitoring were conducted on carbonaceous shale rock specimens. The AE characteristics of carbonaceous shale were investigated, a damage assessment method based on Shannon entropy of AE was further proposed. The results suggest that the mechanical properties of carbonaceous shale intensify with increasing confining pressure and degrade with increasing water content. Moisture in rocks does not only weaken the cohesion but also reduce the internal friction angle of carbonaceous shale. It is observed that AE activities mainly occur in the post-peak stage and the strong AE activities of saturated carbonaceous shale specimens appear at a lower normalized stress level than that of natural-state specimens. The maximum AE counts and AE energy increase with water content while decrease with confining pressure. Both confining pressure and water content induce changes in the proportions of AE dominant frequency bands, but the changes caused by confining pressure are more significant than those caused by water content. The results also indicate that AE entropy can serve as an applicable index for rock damage assessment. The damage evolution process of carbonaceous shale can be divided into two main stages, including the stable damage development stage and the damage acceleration stage. The damage variable increases slowly accompanied by a few AE activities at the first stage, which is followed by a rapid growth along with intense acoustic emission activities at the damage acceleration stage. Moreover, there is a sharp rise in the damage evolution curve for the natural-state specimen at the damage acceleration stage, while the damage variable develops slowly for the saturated-state specimen.

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