Mechanics of Dynamic Ice Failure Against Vertical Structures

2014 ◽  
Author(s):  
Ian Jordaan ◽  
Paul Barrette
Keyword(s):  
Confining Pressure ◽  
Triaxial Tests ◽  
Future Research ◽  
State Variable ◽  
Key Factor ◽  
Modified Ice ◽  
Viscoelastic Theory ◽  
Local Pressures ◽  
Ice Failure ◽  
Prior Stress

Ice interaction with vertical faces of structures can result in regular vibrations given certain conditions such as temperature and speed of interaction. The mechanism that can provide this regular behaviour is studied. Fracture in general does not offer a solution in compressive failure. An approach based on viscoelastic theory, with softening resulting from microstructural change, is given. The pivotal observation was a layer of microstructurally modified ice adjacent to the structure or indentor, together with high local pressures transmitted into the layer. The microstructural changes include microfracturing and recrystallization. A series of triaxial tests was performed to determine the inputs into the viscoelastic theory. The theory recognizes changes in the microstructure of the ice by means of a state variable, which is a function of prior stress history, and therefore of location within the ice mass. The theory and the calibration thereof are reviewed, and the results of triaxial tests examined. One feature of these tests is the occurrence of “runaway” strains and associated localization of damage. This appears to be sensitive to confining pressure, and is considered to be a key factor in the rapid load drops observed in ice-structure interaction. Temperature effects are also studied. Directions for future research are identified.

A Change of Undrain Shear Strength of Soft Ground during Consolidation Process

2014 ◽  
Vol 513-517 ◽  
pp. 269-272
Author(s):  
Yeong Mog Park ◽  
Ik Joo Um ◽  
Norihiko Miura ◽  
Seung Cheol Baek
Keyword(s):  
Shear Strength ◽  
Soft Clay ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Test Results ◽  
Exponential Equation ◽  
Consolidation Process ◽  
Degree Of Consolidation ◽  
Clay Ground ◽  
Strength Increment

The purpose of this study is to investigate the undrain shear strength increment during consolidation process of soft clayey soils. Thirty kinds of laboratory triaxial tests have been performed using undisturbed and remolded Ariake clay samples with different degree of consolidation and 5 kinds of confining pressure. Test results show that well known linear equation proposed by Yamanouchi et al.(1982) is overestimated the strength of undisturbed soft clay ground in the process of consolidation. A new simple and reasonable exponential equation proposed in this paper.

Large-scale triaxial tests of dense gravel material at low confining pressure

2012 ◽  
pp. 587-592
Author(s):  
S Lenart ◽  
J Koseki ◽  
T Sato ◽  
Y Miyashita ◽  
H Thang
Keyword(s):  
Large Scale ◽  
Confining Pressure ◽  
Triaxial Tests

scholarly journals Experimental Study of Stress-Seepage Coupling Properties of Sandstone under Different Loading Paths

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-21
Author(s):  
Xi Chen ◽  
Wei Wang ◽  
Yajun Cao ◽  
Qizhi Zhu ◽  
Weiya Xu ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Pore Pressure ◽  
Complex Loading ◽  
Friction Angle ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Biot Coefficient ◽  
Cyclic Loading And Unloading ◽  
Loading And Unloading

The study on hydromechanical coupling properties of rocks is of great importance for rock engineering. It is closely related to the stability analysis of structures in rocks under seepage condition. In this study, a series of conventional triaxial tests under drained condition and hydrostatic compression tests under drained or undrained condition on sandstones were conducted. Moreover, complex cyclic loading and unloading tests were also carried out. Based on the experimental results, the following conclusions were obtained. For conventional triaxial tests, the elastic modulus, peak strength, crack initiation stress, and expansion stress increase with increased confining pressure. Pore pressure weakened the effect of the confining pressure under drained condition, which led to a decline in rock mechanical properties. It appeared that cohesion was more sensitive to pore pressure than to the internal friction angle. For complex loading and unloading cyclic tests, in deviatoric stress loading and unloading cycles, elastic modulus increased obviously in first loading stage and increased slowly in next stages. In confining pressure loading and unloading cycles, the Biot coefficient decreased first and then increased, which indicates that damage has a great impact on the Biot coefficient.

scholarly journals Resilient modulus and cumulative plastic strain of frozen silty clay under dynamic aircraft loading

2021 ◽  
Vol 3 (10) ◽  
Author(s):  
Xiaolan Liu ◽  
Xianmin Zhang ◽  
Xiaojiang Wang
Keyword(s):  
Plastic Strain ◽  
Resilient Modulus ◽  
Confining Pressure ◽  
Frozen Soil ◽  
Triaxial Tests ◽  
Silty Clay ◽  
Research Findings ◽  
Cumulative Plastic Strain ◽  
Construction Operation ◽  
Compaction Degree

AbstractThis paper describes an investigation into the factors influencing the resilient modulus and cumulative plastic strain of frozen silty clay. A series of dynamic triaxial tests are conducted to analyze the influence of the temperature, confining pressure, frequency, and compaction degree on the resilient modulus and cumulative plastic strain of frozen silty clay samples. The results show that when the temperature is below − 5 °C, the resilient modulus decreases linearly, whereas when the temperature is above − 5 °C, the resilient modulus decreases according to a power function. The resilient modulus increases logarithmically when the frequency is less than 2 Hz and increases linearly once the frequency exceeds 2 Hz. The resilient modulus increases as the confining pressure and compaction degree increase. The cumulative plastic strain decreases as the temperature decreases and as the confining pressure, frequency, and compaction degree increase. The research findings provide valuable information for the design, construction, operation, maintenance, safety, and management of airport engineering in frozen soil regions.

scholarly journals Multi-Layer Quality Inspection System Framework for Industry 4.0

2021 ◽  
Vol 15 (5) ◽  
pp. 641-650
Author(s):  
Victor Azamfirei ◽  
◽  
Anna Granlund ◽  
Yvonne Lagrosen
Keyword(s):  
Industry 4.0 ◽  
Manufacturing Industry ◽  
Production Control ◽  
Measurement Instrument ◽  
Future Research ◽  
Inspection System ◽  
Work Piece ◽  
Quality Inspection ◽  
Industrial Case Study ◽  
Key Factor

In the era of market globalisation, the quality of products has become a key factor for success in the manufacturing industry. The growing demand for customised products requires a corresponding adjustment of processes, leading to frequent and necessary changes in production control. Quality inspection has been historically used by the manufacturing industry to detect defects before customer delivery of the end product. However, traditional quality methods, such as quality inspection, suffer from large limitations in highly customised small batch production. Frameworks for quality inspection have been proposed in the current literature. Nevertheless, full exploitation of the Industry 4.0 context for quality inspection purpose remains an open field. Vice-versa, for quality inspection to be suitable for Industry 4.0, it needs to become fast, accurate, reliable, flexible, and holistic. This paper addresses these challenges by developing a multi-layer quality inspection framework built on previous research on quality inspection in the realm of Industry 4.0. In the proposed framework, the quality inspection system consists of (a) the work-piece to be inspected, (b) the measurement instrument, (c) the actuator that manipulates the measurement instrument and possibly the work-piece, (d) an intelligent control system, and (e) a cloud-connected database to the previous resources; that interact with each other in five different layers, i.e., resources, actions, and data in both the cyber and physical world. The framework is built on the assumption that data (used and collected) need to be validated, holistic and on-line, i.e., when needed, for the system to effectively decide upon conformity to surpass the presented challenges. Future research will focus on implementing and validating the proposed framework in an industrial case study.

scholarly journals ExTaxsI: an exploration tool of biodiversity molecular data

2020 ◽  
Author(s):  
Giulia Agostinetto ◽  
Anna Sandionigi ◽  
Adam Chahed ◽  
Alberto Brusati ◽  
Elena Parladori ◽  
...  
Keyword(s):  
Molecular Data ◽  
Data Availability ◽  
Future Research ◽  
Distribution Data ◽  
Biodiversity Data ◽  
Related Information ◽  
New Information ◽  
Starting Point ◽  
Key Factor ◽  
New Research

AbstractBackgroundThe increasing availability of multi omics data is leading to continually revise estimates of existing biodiversity data. In particular, the molecular data enable to characterize novel species yet unknown and to increase the information linked to those already observed with new genomic data. For this reason, the management and visualization of existing molecular data, and their related metadata, through the implementation of easy to use IT tools have become a key point for the development of future research. The more users are able to access biodiversity related information, the greater the ability of the scientific community to expand the knowledge in this area.ResultsIn our research we have focused on the development of ExTaxsI (Exploring Taxonomies Information), an IT tool able to retrieve biodiversity data stored in NCBI databases and provide a simple and explorable visualization. Through the three case studies presented here, we have shown how an efficient organization of the data already present can lead to obtaining new information that is fundamental as a starting point for new research. Our approach was also able to highlight the limits in the distribution data availability, a key factor to consider in the experimental design phase of broad spectrum studies, such as metagenomics.ConclusionsExTaxI can easily produce explorable visualization of molecular data and its metadata, with the aim to help researchers to improve experimental designs and highlight the main gaps in the coverage of available data.

Overcoming Intersectional Barriers

2018 ◽  
pp. 971-993
Author(s):  
Sara L. Parker ◽  
Kay Standing
Keyword(s):  
Life Experiences ◽  
Future Research ◽  
Key Factors ◽  
Policy Makers ◽  
Key Factor ◽  
Women's Lives ◽  
Just Society ◽  
Set Up ◽  
The Impact ◽  
Research And Policy

This chapter discusses the complexity and challenges of exploring the impact of gender on women's ability to realise their potential in Nepal. It demonstrates the limitations of using binary divisions to exploring ‘gender' as a key factor that impacts upon women's lives. By analysing interviews with ‘inspirational' women in Nepal conducted between 2009 and 2012 the chapter highlights the importance of exploring intersectional factors that also influenced women's life experiences. Based on interviews with 34 ‘inspirational' women in Nepal the chapter explores how the term ‘inspirational' is defines and discusses the range of work being done by so many women in Nepal that is truly inspiring. Through a discourse analysis of their stories of childhood and education we can see what key factors have played a role in enabling these women to realise their potential and to overcome intersectional barriers to work in a range of diverse positions, from the first female District Development Officer to the first women to gain her doctorate from overseas, to women who have set up NGOS working towards a more equitable and just society to others who have set up their own businesses or becoming leading academics. The conclusion draws together some key recommendations for future research and policy makers as well as those seeking to promote more equitable sustainable development that truly includes women in the process as autonomous, heterogeneous actors in the development process

scholarly journals Experimental Study on Dynamic Resilient Modulus of Lime-Treated Expansive Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zheng Lu ◽  
Yang Zhao ◽  
Shaohua Xian ◽  
Hailin Yao
Keyword(s):  
Moisture Content ◽  
Environmental Changes ◽  
Resilient Modulus ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
The Stability ◽  
Compaction Degree

Dynamic resilient modulus is the design index of highway subgrade design code in China, which is significantly affected by the traffic loads and environmental changes. In this study, dynamic triaxial tests were conducted to investigate the influence of moisture content, compaction degree, cyclic deviator stress, and confining pressure on lime-treated expansive soil. The suitability of UT-Austin model to lime-treated expansive soils was verified. The results indicate that the dynamic resilient modulus of lime-treated expansive soils increases nonlinearly with the increase of compaction degree, while decreases nonlinearly with the increase of dynamic stress level. The dynamic resilient modulus decreases linearly with the increase of moisture content and increases linearly with the increase of confining pressure. Moreover, the moisture content has a more significant effect on the dynamic resilient modulus of lime-treated expansive soil. Therefore, it is necessary to ensure the stability of soil humidity state and its excellent mechanical properties under long-term cyclic loading for the course of subgrade filling and service. Finally, the calculated results of the UT-Austin model for dynamic resilient modulus show a good agreement with the test results.

scholarly journals MUSCLE STRENGTH AND CAFFEINE SUPPLEMENTATION: ARE WE DOING MORE OF THE SAME?

2019 ◽  
Vol 25 (2) ◽  
pp. 168-174
Author(s):  
Edgard de Melo Keene Von Koenig Soares ◽  
Giliard Lago Garcia ◽  
Guilherme Eckhardt Molina ◽  
Keila Elizabeth Fontana
Keyword(s):  
Future Research ◽  
Level Of Evidence ◽  
Ergogenic Effects ◽  
Key Factor ◽  
Muscle Groups ◽  
Level I ◽  
Small Muscle ◽  
Intervening Factors ◽  
Isometric Muscle ◽  
Voluntary Strength

ABSTRACT The purpose of this review was to examine in the current literature the advances made in terms of the effects of caffeine supplementation on maximum strength and its associated mechanisms since the publication of two important papers in 2010. Searches were carried out in the PubMed, Medline, Scielo and Web of Science databases for articles published after 2010. Sixteen studies were included based on inclusion and exclusion criteria. Five studies did not report changes in maximal voluntary strength (31.3%). Four of them used isometric muscle contractions, although this may not be a key factor because five other studies also used isometric contractions and reported ergogenic effects. Furthermore, these four studies evaluated small muscle groups and volunteers were not accustomed to consuming caffeine. Caffeine produced ergogenic effects in eleven of the sixteen studies analyzed (68.8%). None of the doses were clearly related to ergogenic effects; however, a dose of at least 3 mg/kg of caffeine is probably necessary. Caffeine ergogenicity was affected by various factors. There was a lack of standardized protocols and controls for intervening factors (e.g., circadian cycles and nutritional states), which could affect results. An ideal caffeine supplementation protocol that is useful for future research, athletes, and physical activity practitioners, has yet to be defined. A small advance made since 2010 involved a possible lack of gender difference; it would appear that caffeine supplementation affects men and women equally. Level of Evidence I; Systematic Review of Level I Studies.

scholarly journals New Structure for Strengthening Soil Embankments

2018 ◽  
Vol 2018 ◽  
pp. 1-16
Author(s):  
Fang Xu ◽  
Wuming Leng ◽  
Rusong Nie ◽  
Qishu Zhang ◽  
Qi Yang
Keyword(s):  
Shear Modulus ◽  
Large Scale ◽  
Dynamic Stress ◽  
Confining Pressure ◽  
Coarse Grained ◽  
Triaxial Tests ◽  
Additional Stress ◽  
Dynamic Shear Modulus ◽  
Dynamic Shear ◽  
Critical Dynamic

A new prestressed reinforcement device (PRD) consisting of two lateral pressure plates (LPPs) and a reinforcement bar is developed to strengthen soil embankments by improving the soil confining pressure and providing lateral constraint on embankment slopes. The reinforcement effects of PRDs were demonstrated by investigating the beneficial effects of increasing confining pressure on the soil behavior via the performance of a series of large-scale static and cyclic triaxial tests on a coarse-grained embankment soil. The results show that PRDs can effectively improve the soil shear strength, bearing capacity, ability to resist elastic and plastic deformation, critical dynamic stress, and dynamic shear modulus, and empirical methods were also developed to determine the critical dynamic stress and initial dynamic shear modulus of the embankment soil. Moreover, 3D finite element analyses (FEAs) with an LPP width of 1.2 m were performed to analyze the additional stress field in a prestressed heavy-haul railway embankment. The FEAs showed that the additional stress at a given external distance from the border of an LPP first increased to a maximum value and then gradually decreased with increasing depth; the additional stress was transferred to the zones where the subgrade tends to have higher stresses with peak stress diffusion angles of 34° (slope direction) and 27° (longitudinal direction); and a continuous effective reinforcement zone with a minimum additional stress coefficient of approximately 0.2 was likely to form at the diffusion surface of the train loads, provided that the net spacing of the LPPs was 0.7 m. The reinforcement zone above the diffusion surface of the train loads can act as a protective layer for the zones that tend to have higher stresses. Finally, the advantages and application prospects of PRDs are discussed in detail. The newly developed PRDs may provide a cost-effective alternative for strengthening soil embankments.

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