A Statistical Analysis of First-Year Level Ice Uniaxial Compressive Strength in the Svalbard Area

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Lucie Strub-Klein
Keyword(s):  
Compressive Strength ◽  
Statistical Analysis ◽  
Failure Mode ◽  
Uniaxial Compressive Strength ◽  
Barents Sea ◽  
Field Investigation ◽  
Visual Observation ◽  
The Arctic ◽  
Sample Orientation ◽  
Level Ice

This paper proposes a methodology for a statistical analysis of uniaxial compressive strength and applies it to full-scale data collected in the Svalbard area from 2005 to 2011. A total of 894 samples were compressed over 7 years of field investigation. The ice was mainly from frozen fjords on Svalbard and also from the Barents Sea and the Arctic Ocean. The analysis consisted in determining the most appropriate distribution for level ice strength according to the sample orientation, the time of the year (which would then relate to the brine configuration in the ice), and the failure mode. Six groups (horizontal, vertical, early, late, brittle, and ductile) were defined, and the gamma, two-parameter Weibull, and lognormal distributions were compared for each group. The Weibull parameters (shape and scale) were estimated with the method of moments and the method of maximum likelihood. The two methods agreed well. A visual observation of quantiles–quantiles plots (QQ-plots) combined with a linear regression and a Kolmogorov–Smirnov (KS) test were conducted to determine the best fitting distribution. Neither the season nor the failure mode appeared to influence the determination of a statistical distribution, contrary to the sample orientation. However, it appeared that the lognormal distribution was a best fit for the failure mode and season groups, whereas the gamma and the Weibull were the best candidates for the vertical and horizontal samples, respectively.

scholarly journals Applying Statistical Analysis and Machine Learning for Modeling the UCS from P-Wave Velocity, Density and Porosity on Dry Travertine

2020 ◽  
Vol 10 (13) ◽  
pp. 4565
Author(s):  
Manuel Saldaña ◽  
Javier González ◽  
Ignacio Pérez-Rey ◽  
Matías Jeldres ◽  
Norman Toro
Keyword(s):  
Machine Learning ◽  
Compressive Strength ◽  
Statistical Analysis ◽  
Uniaxial Compressive Strength ◽  
Wave Velocity ◽  
Accurate Determination ◽  
Effective Porosity ◽  
P Wave ◽  
Strength Parameter ◽  
P Wave Velocity

In the rock mechanics and rock engineering field, the strength parameter considered to characterize the rock is the uniaxial compressive strength (UCS). It is usually determined in the laboratory through a few statistically representative numbers of specimens, with a recommended minimum of five. The UCS can also be estimated from rock index properties, such as the effective porosity, density, and P-wave velocity. In the case of a porous rock such as travertine, the random distribution of voids inside the test specimen (not detectable in the density-porosity test, but in the compressive strength test) causes large variations on the UCS value, which were found in the range of 62 MPa for this rock. This fact complicates a sufficiently accurate determination of experimental results, also affecting the estimations based on regression analyses. Aiming to solve this problem, statistical analysis, and machine learning models (artificial neural network) was developed to generate a reliable predictive model, through which the best results for a multiple regression model between uniaxial compressive strength (UCS), P-wave velocity and porosity were obtained.

scholarly journals Research on crack evolution law and macroscopic failure mode of joint Phyllite under uniaxial compression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jiangbo Xu ◽  
Dongyang Fei ◽  
Yanglin Yu ◽  
Yilun Cui ◽  
Changgen Yan ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Failure Mode ◽  
Uniaxial Compression ◽  
Uniaxial Compressive Strength ◽  
Stress Level ◽  
Joint Effect ◽  
Crack Evolution ◽  
Evolution Law ◽  
Joint Inclination ◽  
Original Crack

AbstractIn order to explore the fracture mechanism of jointed Phyllite, the TAJW-2000 rock mechanics test system is used to carry out uniaxial compression tests on different joint inclination Phyllites. The influence of joint inclination of Phyllite failure mode is discussed, and the progressive failure process of Phyllite is studied. The test results show that the uniaxial compressive strength anisotropy of jointed Phyllite is remarkable. As the inclination increases, it exhibits a U-shaped change; When 30° ≤ α ≤ 75°, the tensile and shear failures along the joint inclination mainly occurs. the joint inclination controls the failure surface form of the Phyllite; The crack initial stress level of the joint Phyllite is 0.30–0.59σf, the crack failure stress level is 0.44–0.86σf. When α = 90°, the σcd value is the largest, and σcd with α = 90° can be used as the maximum reliable value of uniaxial compressive strength of Phyllite. Using the theory of fracture mechanics, it is analyzed that under uniaxial compression of the rock, the crack does not break along the original crack direction, but extends along the direction at a certain angle to the original crack. The joint effect coefficient is proposed to show the influence of the joint inclination on the uniaxial compressive strength of the phyllite. Both the test and simulation results show that when the joint inclination is 60°, the joint effect coefficient is the largest. The compressive strength is the smallest. Numerical simulation analyses the crack evolution law of phyllite under different joint inclination under uniaxial compression, which verifies that there are different failure modes of joint phyllite under uniaxial compression.

The uniaxial compressive strength of the Arctic summer sea ice

2015 ◽  
Vol 34 (1) ◽  
pp. 129-136 ◽  
Author(s):  
Hongwei Han ◽  
Zhijun Li ◽  
Wenfeng Huang ◽  
Peng Lu ◽  
Ruibo Lei
Keyword(s):  
Compressive Strength ◽  
Sea Ice ◽  
Uniaxial Compressive Strength ◽  
The Arctic ◽  
Arctic Summer

scholarly journals Field investigation and analysis of rockburst and spalling in  a deep hard-rock mine

2021 ◽  
Author(s):  
Xiao Peng ◽  
Zhao Guoyan ◽  
Liu Huanxin
Keyword(s):  
Compressive Strength ◽  
Tangential Stress ◽  
Uniaxial Compressive Strength ◽  
Strain Energy ◽  
Hard Rock ◽  
Field Investigation ◽  
Surrounding Rock ◽  
Maximum Tangential Stress ◽  
Ground Pressure ◽  
Energy Absorbing

Abstract In order to investigate the ground pressure disasters in deep hard-rock mines, field investigation and theoretical analysis were carried out in a deep hard-rock mine. It is found that the degree and number of ground pressure disasters in the mine have increased significantly with depth. When the maximum tangential stress between 0.4-0.6 times the uniaxial compressive strength of surrounding rock, surrounding rock is prone to local spalling. When maximum tangential stress is greater than 0.6 times uniaxial compressive strength, serious failure is easy to occur, such as rockbursts and large-area collapses. After excavation, the rebound strain and displacement of surrounding rock increases linearly with buried depth, and the strain energy released of surrounding rock increases rapidly with the second power of buried depth. The rapidly increasing strain energy is main reason why deep ground pressure disasters in the mine are becoming more and more serious. In terms of surrounding rock support, energy-absorbing materials such as energy-absorbing bolts can well absorb strain energy released by surrounding rock. The energy-absorbing bolts are used for design of roadway support in the mine.

scholarly journals Effect of Wheel/Rail Loads on Concrete Tie Stresses and Rail Rollover

2011 ◽  
Author(s):  
Brian P. Marquis ◽  
Michelle Muhlanger ◽  
David Y. Jeong
Keyword(s):  
Compressive Strength ◽  
Research And Development ◽  
Closed Form ◽  
Failure Mode ◽  
Research Program ◽  
Field Investigation ◽  
Pattern Of Failure ◽  
Safety Criterion ◽  
Contact Conditions ◽  
Compressive Strength Of Concrete

As a result of vertical and lateral wheel/rail forces, high contact stresses can develop at the interface between the rail base and tie. Under certain conditions, these stresses can exceed the strength of the concrete tie and result in deterioration of the tie and ultimately derailment due to rail rollover. This failure mode has been determined to be the probable cause of at least two derailments where the ties were found to have a triangular wear pattern. Following these derailments, a field investigation revealed this pattern of failure present in an appreciable portion of concrete ties [1]. Closed-form analyses have been conducted to examine combinations of wheel/rail loads and contact conditions that produce concrete tie rail seat deterioration or rail rollover. These results indicate that under certain circumstances truck-side L/V permitted by the Federal Railroad Administration (FRA) Safety Criterion on Wheel/Rail Loads can result in stresses above the AREMA specified minimum design compressive strength of concrete used in concrete ties. Furthermore the analysis indicated that under certain circumstances truck-side L/V permitted by the FRA Safety Criterion can result in rail rollover. The analyses show that rail rollover can be a problem for new concrete ties, but is more of a problem in the presence of rail seat deterioration described above. This work is sponsored by FRA Office of Research and Development under the track research program.

Summer phytoplankton of the northern Barents Sea (75–80º N)

2019 ◽  
pp. 8-19
Author(s):  
Larisa A. Pautova ◽  
Vladimir A. Silkin ◽  
Marina D. Kravchishina ◽  
Valeriy G. Yakubenko ◽  
Anna L. Chultsova
Keyword(s):  
Barents Sea ◽  
Weighted Average ◽  
Arctic Basin ◽  
High Arctic ◽  
Alexandrium Tamarense ◽  
Warm Water ◽  
The Arctic ◽  
Absolute Maximum ◽  
Deep Trench ◽  
Maximum Biomass

The structure of the summer planktonic communities of the Northern part of the Barents sea in the first half of August 2017 were studied. In the sea-ice melting area, the average phytoplankton biomass producing upper 50-meter layer of water reached values levels of eutrophic waters (up to 2.1 g/m3). Phytoplankton was presented by diatoms of the genera Thalassiosira and Eucampia. Maximum biomass recorded at depths of 22–52 m, the absolute maximum biomass community (5,0 g/m3) marked on the horizon of 45 m (station 5558), located at the outlet of the deep trench Franz Victoria near the West coast of the archipelago Franz Josef Land. In ice-free waters, phytoplankton abundance was low, and the weighted average biomass (8.0 mg/m3 – 123.1 mg/m3) corresponded to oligotrophic waters and lower mesotrophic waters. In the upper layers of the water population abundance was dominated by small flagellates and picoplankton from, biomass – Arctic dinoflagellates (Gymnodinium spp.) and cold Atlantic complexes (Gyrodinium lachryma, Alexandrium tamarense, Dinophysis norvegica). The proportion of Atlantic species in phytoplankton reached 75%. The representatives of warm-water Atlantic complex (Emiliania huxleyi, Rhizosolenia hebetata f. semispina, Ceratium horridum) were recorded up to 80º N, as indicators of the penetration of warm Atlantic waters into the Arctic basin. The presence of oceanic Atlantic species as warm-water and cold systems in the high Arctic indicates the strengthening of processes of “atlantificacion” in the region.

scholarly journals Experimental Analysis of the Mechanical Properties and Resistivity of Tectonic Coal Samples with Different Particle Sizes

Energies ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2303
Author(s):  
Congyu Zhong ◽  
Liwen Cao ◽  
Jishi Geng ◽  
Zhihao Jiang ◽  
Shuai Zhang
Keyword(s):  
Mechanical Properties ◽  
Particle Size ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Uniaxial Compressive Strength ◽  
Coalbed Methane ◽  
Coal Sample ◽  
Fine Particles ◽  
Particle Sizes ◽  
Tectonic Coal

Because of its weak cementation and abundant pores and cracks, it is difficult to obtain suitable samples of tectonic coal to test its mechanical properties. Therefore, the research and development of coalbed methane drilling and mining technology are restricted. In this study, tectonic coal samples are remodeled with different particle sizes to test the mechanical parameters and loading resistivity. The research results show that the particle size and gradation of tectonic coal significantly impact its uniaxial compressive strength and elastic modulus and affect changes in resistivity. As the converted particle size increases, the uniaxial compressive strength and elastic modulus decrease first and then tend to remain unchanged. The strength of the single-particle gradation coal sample decreases from 0.867 to 0.433 MPa and the elastic modulus decreases from 59.28 to 41.63 MPa with increasing particle size. The change in resistivity of the coal sample increases with increasing particle size, and the degree of resistivity variation decreases during the coal sample failure stage. In composite-particle gradation, the proportion of fine particles in the tectonic coal sample increases from 33% to 80%. Its strength and elastic modulus increase from 0.996 to 1.31 MPa and 83.96 to 125.4 MPa, respectively, and the resistivity change degree decreases. The proportion of medium particles or coarse particles increases, and the sample strength, elastic modulus, and resistivity changes all decrease.

scholarly journals Phylogeography of the Brittle Star Ophiura sarsii Lütken, 1855 (Echinodermata: Ophiuroidea) from the Barents Sea and East Atlantic

Diversity ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 40
Author(s):  
Evgeny Genelt-Yanovskiy ◽  
Yixuan Li ◽  
Ekaterina Stratanenko ◽  
Natalia Zhuravleva ◽  
Natalia Strelkova ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Barents Sea ◽  
Haplotype Diversity ◽  
Brittle Star ◽  
The Arctic ◽  
Coi Gene ◽  
High Genetic Diversity ◽  
Svalbard Archipelago ◽  
Mitochondrial Coi ◽  
The Barents Sea

Ophiura sarsii is a common brittle star species across the Arctic and Sub-Arctic regions of the Atlantic and the Pacific oceans. Ophiurasarsii is among the dominant echinoderms in the Barents Sea. We studied the genetic diversity of O.sarsii by sequencing the 548 bp fragment of the mitochondrial COI gene. Ophiurasarsii demonstrated high genetic diversity in the Barents Sea. Both major Atlantic mtDNA lineages were present in the Barents Sea and were evenly distributed between the northern waters around Svalbard archipelago and the southern part near Murmansk coast of Kola Peninsula. Both regions, and other parts of the O.sarsii range, were characterized by high haplotype diversity with a significant number of private haplotypes being mostly satellites to the two dominant haplotypes, each belonging to a different mtDNA clade. Demographic analyses indicated that the demographic and spatial expansion of O.sarsii in the Barents Sea most plausibly has started in the Bølling–Allerød interstadial during the deglaciation of the western margin of the Barents Sea.

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