Seafloor Polymetallic Sulfides Mechanical Property Test

2014 ◽  
Vol 1015 ◽  
pp. 316-319
Author(s):  
Zhong Hua Huang ◽  
Shao Jun Liu ◽  
Ying Guang Xu ◽  
Wang Hu
Keyword(s):  
Compressive Strength ◽  
Internal Friction ◽  
Uniaxial Compressive Strength ◽  
Compression Strength ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Test Method ◽  
Dry Density ◽  
Average Value

Seafloor polymetallic sulfide specimens were developed according to engineering rock test method standard (GB/T 50266-2013). Seafloor polymetallic sulfide wet density and dry density were tested. Uniaxial compressive strength and triaxial compression strength of seafloor polymetallic sulfide were tested using rock mechanics test system MTS 815. Elasticity modulus and Poisson's ratio of seafloor polymetallic sulfide were calculated based on specimens stress-strain curves. Cohesion and internal friction angle were calculated based on specimens triaxial test Mohr stress circle. Test results show that seafloor polymetallic sulfide dry density average value is 2.6 g/cm3, wet density average value is 2.94 g/cm3. Uniaxial compressive strength and triaxial compression strength of seafloor polymetallic sulfide are unstable. Average value of the uniaxial compressive strength is 10.243MPa. Average value of triaxial compression strength test peak load is 47.166KN. Cohesion is 2.447MPa and internal friction angle is 38.04o.

scholarly journals Experimental Study on the Effect of Freezing and Thawing on the Shear Strength of the Frozen Soil in Qinghai-Tibet Railway Embankment

2022 ◽  
Vol 2022 ◽  
pp. 1-12
Author(s):  
B. Wang ◽  
J. H. Gao ◽  
Y. Q. Wang ◽  
X. J. Quan ◽  
Y. W. Gong ◽  
...  
Keyword(s):  
Growth Rate ◽  
Internal Friction ◽  
Moisture Content ◽  
Initial Moisture Content ◽  
Friction Angle ◽  
Frozen Soil ◽  
Internal Friction Angle ◽  
Freezing Process ◽  
Dry Density ◽  
Freezing And Thawing

The direct shear tests of different dry density and moisture content samples at different temperatures of the frozen soil in the Qinghai-Tibet Railway embankment between Tanggula South and Anduo section were carried out to analyze the influence rules of each experimental factor on the mechanical properties of frozen soil during the freeze-thaw process. The results show the following. (1) When the frozen soil temperature is below 0°C and continues to drop during the freezing and thawing process, each sample shows the law of a significant increase in cohesion and a slight decrease in the internal friction angle. In the meantime, the cohesion obtained during the thawing process of the sample at the same temperature point is higher than that obtained during the freezing process. In contrast, the internal friction angles exhibit an opposite law, where the internal friction angle during the melting process is lower than the internal friction angle during the freezing process. After freezing-thawing action, it deserves to be mentioned that the cohesion increases slightly while the internal friction angles present a slight decrease trend compared to the initial state. (2) With the decrease in temperature and the gradual increase in cohesion, the temperature curve can be divided into a fast-growing section from 0 to −2°C, a slow-growing section from −2 to −8°C, and a second fast-growing section from −8 to −10°C owing to the combined effect of the pressure-thawing action and ice-water phase change. In addition, the rate of decrease in the internal friction angle also shows a similar pattern. (3) The cohesion and the internal friction angle of samples both tend to increase first and then decrease with the rise of the initial moisture content, and the critical initial moisture content is near the optimal moisture content of 15%. (4) Both the cohesion and the internal friction angle of the samples increase with dry density growth. The growth rate of cohesion will gradually increase as the temperature decreases. Moreover, the growth rate of cohesion of low dry density samples is more susceptible to temperature, while the internal friction angle growth rate is not affected by temperature.

Testing of Strength Parameters and Deformation Parameters of Surrounding Rock and their Distributions

2011 ◽  
Vol 261-263 ◽  
pp. 1360-1364 ◽  
Author(s):  
Chun Ling Yan ◽  
De Xin Ding ◽  
Yi Qun Tang ◽  
Zhong Wei Bi
Keyword(s):  
Tensile Strength ◽  
Internal Friction ◽  
Normal Distribution ◽  
Lognormal Distribution ◽  
Hypothesis Test ◽  
Probability Distributions ◽  
Hanging Wall ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Test Method

Cores were taken from the hanging wall of the III -1 ore body at Kangjiawan Lead, Zinc and Gold Mine. 50 samples for compression and tension tests were fabricated. 50 compressive and 50 tensile strength values were obtained by RMT-150B testing systems. The probability distributions for the compressive and tensile strength were tested by the hypothesis test method. It proves that uniaxial compressive strength follows normal distribution and tensile strength follows the lognormal distribution. And it proves that elastic modulus and Poson’s ratio follow normal distribution. 50 pairs of cohesion and internal friction angle were obtained by randomly drawing a uniaxial compressive and tensile strength samples from 50 measured values. Cohesion follows lognormal distribution and internal friction angle follows normal distribution through hypothesis test method. With the results, some references can be conveniently provided for prediction of the strength and distribution of similar rocks in related geotechnical projects.

scholarly journals Mechanical properties and damage mode of cemented tailings backfill in an acidic environment

2021 ◽  
Vol 121 (6) ◽  
Author(s):  
Y. Huang ◽  
G. Wang ◽  
Y. Rao ◽  
W. Liu
Keyword(s):  
Compressive Strength ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Sulphuric Acid ◽  
Damage Evolution ◽  
Acid Corrosion ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Acidic Environment ◽  
Corrosion Time

SYNOPSIS The properties and deterioration in strength of cemented tailings backfill (CTB )in the underground acidic environment under oxidizing conditions were studied. X-ray diffraction analysis and scanning electron microscopy of the surface of the CTB was carried out, and the sulphuric acid corrosion mechanism elucidated. The properties tested included compressive strength, elastic modulus, cohesion, internal friction angle, variation in the hydrogen ion concentration, and stress-strain relationship in different corrosion periods. The damage model of the CTB was established considering the effects of parameters such as corrosion time and strain on the damage evolution. It was found that the compressive strength, elastic modulus, cohesion (binder effect), and internal friction angle increased at first and then decreased with exposure time. In the long term, the peak stress decreased with corrosion time while the peak strain increased; elastic modulus, and deformation modulus also decreased. The damage caused by corrosion and by load were related by means of a mathematical model, which revealed the relationships between sulphuric attack, load, and damage to backfill in complex underground environments. During corrosion, the expansion of gypsum and ettringite caused microfractures in the CTB. With increasing corrosion time, micro-cracks developed and proliferated. The mechanism of corrosion damage was found to be the dissolution of hydrogen ions and a sulphate ion reaction that produces an expansive substance, resulting in deterioration of the strength of CTB. Keywords: underground environment, sulphuric acid corrosion, porosity, cemented tailings backfill, damage evolution model.

scholarly journals Effect of Freeze-Thaw Cycles on the Mechanical Properties of Polyacrylamide- and Lignocellulose-Stabilized Clay in Tibet

2021 ◽  
Vol 2021 ◽  
pp. 1-16
Author(s):  
Haiping Shi ◽  
Zhongyao Li ◽  
Wenwei Li ◽  
Shaopeng Wang ◽  
Baotian Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Internal Friction ◽  
Unconfined Compressive Strength ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Test Results ◽  
Freeze Thaw ◽  
Original Strength ◽  
Compressive Tests

Laboratory freezing experiments were conducted to evaluate the effect of polyacrylamide (PAM) and lignocellulose on the mechanical properties and microstructural characteristics of Tibetan clay. Direct shear and unconfined compressive tests and field emission scanning electron microscopy analyses were performed on clay samples with different contents of stabilizers. The test results show that the addition of PAM can improve the unconfined compressive strength and cohesion of Tibetan clay, but an excessive amount of PAM reduces the internal friction angle. After several freeze-thaw cycles, the unconfined compressive strength and cohesion of samples stabilized by PAM decrease significantly, while the internal friction angle increases. Samples stabilized by PAM and lignocellulose have higher internal friction angles, cohesion, and unconfined compressive strength and can retain about 80% of the original strength after 10 freeze-thaw cycles. PAM fills the pores between soil particles and provides adhesion. The addition of lignocellulose can form a network, restrict the expansion of pores caused by freeze-thaw cycles, and improve the integrity of PAM colloids. It is postulated that the addition of a composite stabilizer with a PAM content of 0.4% and a lignocellulose content of 2% may be a technically feasible method to increase the strength of Tibetan clay.

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.

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.

scholarly journals Influences of Curing Environment on Strength Performances of Shanghai Clayey Soil Reinforced with Palm Fiber

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Jili Qu ◽  
Kun Xiong
Keyword(s):  
Compressive Strength ◽  
Shear Strength ◽  
Internal Friction ◽  
Shear Modulus ◽  
Unconfined Compressive Strength ◽  
Clayey Soil ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Curing Conditions ◽  
Palm Fiber

Owing to its environment-friendly, economically available, and sustainable property, the palm fiber was attempted to improve the quality of Shanghai clayey soil together with lime. The direct shear tests (DST), ultrasonic pulse velocity tests (UPV), and the unconfined compressive tests (UCT) have been carried out on soils mixed with palm fiber and lime under 3 curing conditions of immersion in water, cyclic wetting-drying, and air curing at a series of contents of additives. The corresponding indexes of shear strength (τ), cohesion (c), internal friction angle (φ), initial shear modulus (G0), and unconfined compressive strength (qu) were obtained and analyzed. Results show that immersed-in-water environment is optimum for the formation of shear strength, initial shear modulus, cohesion, and unconfined compressive strength (UCS), while the air curing condition is the worst for admixture treated soil. Lime can increase G0, but palm fiber can slightly reduce G0. Lime has significant effect on increase of internal friction angle; on the contrary, palm fiber has only limited effect. c/G0 for any type of sample remains almost constant under different curing conditions. It demonstrates that c and G0 possess the comparative development trend under different curing environment.

Experimental Study on Shear Strength of West Sichuan Unsaturated Mixed-Soil

2013 ◽  
Vol 353-356 ◽  
pp. 772-778 ◽  
Author(s):  
Kai Cui ◽  
Bang Wen Huang
Keyword(s):  
Internal Friction ◽  
Moisture Content ◽  
Water Content ◽  
Mineral Water ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Cohesive Force ◽  
Dry Density ◽  
Control Matrix ◽  
Matrix Suction

By controlling moisture content to control matrix suction indirectly, three typical unsaturated remolded mixed-soil from west Sichuan are studied by the consolidated untrained triaxial shear test .The test data show that for different kinds of soil samples, the sample with less amount of clay and high content of quartz has bigger internal friction angle relatively, and the sample with hydrophilic mineral and high content of clay has bigger cohesive force. Meanwhile, for the sample without or less hydrophilic mineral, cohesive force is affected mainly by water content, and for the sample with large content of hydrophilic mineral, water content and dry density affect cohesive force together. For a certain sample, the variation of moisture content and dry density affects internal friction angle less, while affects cohesive force more. In addition, the change of internal friction angle resulting from the variation of matrix suction is less, and cohesive force increases as matrix suction increases.

scholarly journals Strength of Vegetated Coal-Bearing Soil under Dry-Wet Cycles: An Experimental Study

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Gang Huang ◽  
Mingxin Zheng
Keyword(s):  
Internal Friction ◽  
Water Content ◽  
Southern China ◽  
Orthogonal Design ◽  
Friction Angle ◽  
Chain Structure ◽  
Internal Friction Angle ◽  
Soil Reinforcement ◽  
Dry Density ◽  
Mineral Particles

Strength of vegetated coal-bearing soil is of great significance to evaluate the shallow stability of vegetated slopes in coal-bearing soil regions. This paper takes D-W cycles, dry density, water content, and vegetation root (VR) content as four factors and carries out the triaxial test for the orthogonal design of vegetated coal-bearing soil in southern China. The strength curves of vegetated coal-bearing soil under four factors were obtained. The Taguchi method was used to quantitatively analyse the effects of four factors. The microstructure of coal-bearing soil under D-W cycles and the theory of soil reinforcement by VR were discussed. The results indicated that D-W cycles had a significant effect on the cohesion and internal friction angle ( P < 0.05 ). The internal friction angle was little affected by the water content and VR content, which had considerable influence on the cohesion. The cohesion could be improved with less than 2% VR content. The cohesion was the largest for no D-W cycles, 10% water content, and 2% VR content. The links between mineral particles go from a stable layered structure to unsteadiness chain structure with the increase in the number of D-W cycles.

scholarly journals Influence of Water Content on the Mechanical Parameters of the Intact Rock and Rock Mass

2018 ◽  
Author(s):  
Balázs Vásárhelyi ◽  
Morteza Davarpanah
Keyword(s):  
Tensile Strength ◽  
Compressive Strength ◽  
Rock Mass ◽  
Internal Friction ◽  
Water Content ◽  
Uniaxial Compressive Strength ◽  
Water Saturation ◽  
Friction Angle ◽  
Intact Rock ◽  
Mechanical Parameters

The goal of this paper is to present the influence of the water saturation of the intact rock on different mechanical parameters, such as internal friction angle, cohesion, Hoek-Brown constant (mi ). Analyzing the previously published results, it was found that due to water saturation both the uniaxial compressive strength and tensile strength decrease similarly, i.e. the ratio of these two values is constant, thus the internal friction angle does not change but only the cohesion. Likewise, Hoek-Brown constant (mi ) remains constant; it is independent on the moisture content.The ratio of the elastic modulus and the uniaxial compressive strength of the intact rock is also calculated. According to the laboratory results, this ratio (namely modulus ratio) is also independent on the water content.It is shown that the mechanical parameters of the rock mass (such as compressive strength, tensile strength, deformation modulus) similarly depend on the water content than the intact rock.

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