scholarly journals Influencing Factors for the Instability and Collapse Mode of the Goaf Structure in a Gypsum Mine

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Zhaowen Du ◽  
Zhihe Liu ◽  
Rui Liu ◽  
Sheng Wang ◽  
Faxin Li
Keyword(s):  
Compressive Strength ◽  
Water Temperature ◽  
Failure Mechanism ◽  
Influencing Factors ◽  
Uniaxial Compressive Strength ◽  
Large Area ◽  
Multiple Factors ◽  
Collapse Mode ◽  
Strength Tests ◽  
Gypsum Rock

Large-area goafs in a gypsum mine tend to collapse after 10 or more years, but the influencing factors are still unclear, and the effects of multiple factors have not been comprehensively considered. In this study, the failure mechanism and collapse mode of the room-pillar goaf structure were analyzed, and the uniaxial compressive strength tests of the pillars under different conditions were carried out in a laboratory. The influences of water, temperature, and time on the strength of the gypsum rock were considered. These three factors weakened the gypsum rock in different degrees. After 120 days of immersion, water had the greatest effect with a strength-weakening rate of 52.61%. After 20 temperature cycles, changes in temperature had little effect with a strength-weakening rate of 12.60%. After 25 years of aging, the strength-weakening rate of time was 25.13%. These results show how different factors affect the instability and collapse of the goaf structure, which are of great significance for predicting and preventing this from happening.

scholarly journals Plane-Strain Compressive Strength of Columnar-Grained and Granular-Snow Ice

1977 ◽  
Vol 18 (80) ◽  
pp. 505-516 ◽  
Author(s):  
R. Frederking
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Plane Strain ◽  
Uniaxial Compressive Strength ◽  
Ice Cover ◽  
Anisotropic Structure ◽  
Compression Tests ◽  
Isotropic Structure ◽  
Plane Strain Case

Abstract An ice cover impinging on a long straight structure is assumed to be under a condition of plane strain. A technique is described for performing plane-strain compression tests, and results are presented for the strain-rate dependence of strength. The plane-strain compressive strength of ice having anisotropic structure (columnar-grained ice) is at least two and a half times the uniaxial compressive strength, whereas the plane-strain compressive strength of ice having an isotropic structure (granular-snow ice) is at most 25% greater than the uniaxial case. The greater plane-strain compressive strength of columnar grained ice when the loading and confining directions are in the plane of the ice cover, can be attributed to its anisotropic structure, which leads to a different failure mechanism for the plane-strain case.

EFFECT OF PETROLOGICAL FEATURES ON MECHANICAL PROPERTIES OF ROCK SALT FROM THE LGOM (LEGNICA–GŁOGÓW COPPER DISTRICT)

2016 ◽  
pp. 51-64 ◽  
Author(s):  
Katarzyna CYRAN ◽  
Tomasz TOBOŁA ◽  
Paweł KAMIŃSKI
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Rock Salt ◽  
Fluid Inclusions ◽  
Mechanical Parameters ◽  
Research Results ◽  
Strength Tests ◽  
Crystal Boundaries

The paper presents the attempt to find a correlation between the content of impurities and mechanical parameters of rock salt from the LGOM. Research was carried out in three steps: uniaxial compressive strength tests, determination of the content of insoluble minerals (impurities), and observations under the microscope and Raman microspectroscopy. The research results reveal that the rock salt which is characterized by low content of insoluble minerals (0.13–2.11% wt.) shows no correlation between the mechanical properties and the content of impurities. However, it was found that mechanical properties depend on both the distribution of impurities in halite crystals and the presence of fluid inclusions and hydrocarbons along the crystal boundaries. Moreover, the distribution of anhydrite at the edges of halite crystals may influence an increase of rock salt strength. On the contrary, the presence of fluid inclusions and hydrocarbons along the halite crystal boundaries may reduce the rock salt strength.

scholarly journals Plane-Strain Compressive Strength of Columnar-Grained and Granular-Snow Ice

1977 ◽  
Vol 18 (80) ◽  
pp. 505-516 ◽  
Author(s):  
R. Frederking
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Plane Strain ◽  
Uniaxial Compressive Strength ◽  
Ice Cover ◽  
Anisotropic Structure ◽  
Compression Tests ◽  
Isotropic Structure ◽  
Plane Strain Case

AbstractAn ice cover impinging on a long straight structure is assumed to be under a condition of plane strain. A technique is described for performing plane-strain compression tests, and results are presented for the strain-rate dependence of strength. The plane-strain compressive strength of ice having anisotropic structure (columnar-grained ice) is at least two and a half times the uniaxial compressive strength, whereas the plane-strain compressive strength of ice having an isotropic structure (granular-snow ice) is at most 25% greater than the uniaxial case. The greater plane-strain compressive strength of columnar grained ice when the loading and confining directions are in the plane of the ice cover, can be attributed to its anisotropic structure, which leads to a different failure mechanism for the plane-strain case.

scholarly journals Plane-Strain Compressive Strength of Columnar-Grained and Granular-Snow Ice

1977 ◽  
Vol 19 (81) ◽  
pp. 657-658
Author(s):  
R. Frederking
Keyword(s):  
Compressive Strength ◽  
Strain Rate ◽  
Failure Mechanism ◽  
Plane Strain ◽  
Uniaxial Compressive Strength ◽  
Ice Cover ◽  
Anisotropic Structure ◽  
Compression Tests ◽  
Isotropic Structure ◽  
Plane Strain Case

AbstractAn ice cover impinging on a long straight structure is assumed to be under a condition of plane strain. A technique is described for performing plane-strain compression tests, and results are presented for the strain-rate dependence of strength. The plane-strain compressive strength of ice having anisotropic structure (columnar-grained ice) is at least two and a half times the uniaxial compressive strength, whereas the plane-strain compressive strength of ice having an isotropic structure (granular-snow ice) is atmost 25% greater than the uniaxial case. The greater plane-strain compressive strength of columnar-grained ice, when the loading and confining directions are in the plane of the ice cover, can be attributed to its anisotropic structure, which leads to a different failure mechanism for the plane-strain case.

scholarly journals Influence of Specimen Size and Shape on the Uniaxial Compressive Strength Values of Rocks

2021 ◽  
Author(s):  
Tatiana Durmeková ◽  
Martin Bednarik ◽  
Petra Dikejová ◽  
Renáta Adamcová
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Rock Specimen ◽  
Slenderness Ratio ◽  
Factors Affecting ◽  
Size And Shape ◽  
Strength Tests ◽  
Ucs Test ◽  
Variable Impact ◽  
Significant Factors

Abstract The most significant factors affecting the results of Uniaxial Compressive Strength (UCS) test are the size, slenderness ratio h/d (ratio of height to diameter), and the shape of the rock specimen. The proposed experimental study shows the variable impact of these parameters on UCS values by implementing several lithological types. Standard strength tests were performed on four lithological types: granodiorite, limestone, sandstone and andesite. Cylindric and cube-shaped test specimens of different sizes were prepared from each rock. Cylindric specimens with diameter 20 mm, 35 mm, 50 mm and 70 mm with height to diameter ratio of 1:1 and 2:1, and cubic and prismatic specimens with an edge dimension of 50 mm were tested and analyzed. Obtained results of strength tests confirmed a high variability of current research opinions on how the size and shape of specimens influence the strength values of rocks. The study revealed the impossibility of conclusive correlations between the UCS and specimens to be generally applicable for all lithological types. Of the observed effects on the strength, the aspect of the specimen slenderness ratio was the most pronounced on all studied rocks.

scholarly journals Stiffness and Strength of Granular Soils Improved by Biological Treatment Bacteria Microbial Cements

2018 ◽  
Vol 2 (4) ◽  
Author(s):  
Mehdi Jalili ◽  
Mohmad Reza Ghasemi ◽  
Ali Reza Pifloush
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Physical And Mechanical Properties ◽  
Soil Improvement ◽  
Granular Soils ◽  
Industrial Town ◽  
Strength Tests ◽  
Problematic Soils ◽  
Strength And Stiffness

In some parts of the world mechanical properties of problematic soils are not suitable for construction purposes. Today, regard to the importance of the soil improvement; by considering methods with more concordance with the environmental mechanisms in the nature, and with study and combination of geotechnical science, microbiology and geochemistry; researchers try to provide a suitable way to improve the physical and mechanical properties of the problematic soils. In this paper, the effect of the aerobic microorganisms of Sporosarsina Pasteurii (PTCC 1645), as a producer of Urease for the sedimentation of calcium carbonate and improvement of granular soil of Garmsar Industrial Town is evaluated experimentally in order to check the effects of this phenomena on the shear strength and stiffness of the granular soils. The results of the uniaxial compressive strength tests show the effect of adding the above mentioned microbial solution to the soils, in case of increased uniaxial compressive strength and stiffness of the soil. It should be mentioned that the granular soils have no compressive strength, naturally but after bio cementation the samples got notable values.

Large-Scale Ice Strength Tests at Slow Strain Rates

1988 ◽  
Vol 110 (3) ◽  
pp. 302-306 ◽  
Author(s):  
A. C. T. Chen ◽  
J. Lee
Keyword(s):  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Large Scale ◽  
Failure Modes ◽  
Sheet Thickness ◽  
Crystallographic Structure ◽  
Strain Rates ◽  
Strength Tests ◽  
Loading System ◽  
Ice Strength

In the winter of 1979/80, five petroleum companies participated in an Exxon Production Research Company program in which thirteen large-scale ice strength tests were conducted offshore in the vicinity of Prudhoe Bay. The purpose of the program was to determine the uniaxial compressive strength of annual sea ice as a function of strain rate and direction of loading with respect to preferred crystal alignment. Full ice sheet thickness test blocks with dimensions of 10 ft × 20 ft (3.05 m × 6.10 m) were cut free from the surrounding sheet ice. A hydraulic loading system with two million pounds of force capacity was used to compress the ice blocks at constant strain rates ranging from 10−7 s−1 to 10−5 s−1. Deformation in three orthogonal dimensions along with the axial had were measured and recorded throughout the test. This paper describes the field operations and test results, including uniaxial compressive strength, stiffness, Poisson’s ratio, and failure modes. Measured ice temperature, salinity and crystallographic structure are also presented.

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