scholarly journals Study on Catastrophe Instability of Support System in Gypsum Goaf Based on Energy Dissipation Theory

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Yuejin Zhou ◽  
Xiaoding Xu ◽  
Xiaotong Li ◽  
Meng Li ◽  
Yugui Yang
Keyword(s):  
Energy Dissipation ◽  
Support System ◽  
Catastrophe Theory ◽  
Field Research ◽  
Geometric Parameters ◽  
Mechanical Instability ◽  
Static State ◽  
Geometric Deformation ◽  
Quasistatic Process ◽  
The Stability

The stability of the goaf support system is the key to safe production in gypsum mines. Therefore, this study constructed a pillar-beam support system which contained pillar plastic zones. In this support system, the beam and pillar were taken as energy releaser and energy dissipater, respectively. Through establishing a cusp catastrophe model based on energy theory, the new criterion for instability was obtained which is related with geometric stiffness and system energy dissipation. The results indicate the instability of the support system is caused by the incompatibility of energy release, dissipation, and geometric deformation. When K > 1, the energy released by the support system is compatible with geometric deformation. The support system experiences a quasistatic process from the static state in bottom page to the static state in top page along Path I. When K < 1, the energy released by the support system cannot be in tune with geometric deformation. The support system experiences a catastrophe process along Path II. The evolution from the static state in bottom page to the static state in top page is not progressive, but catastrophic. The redundant energy released in this process leads to mechanical instability of the support system. This study provided theoretical foundation for the mining and treatment of mines. Based on actual engineering examples, the sensitivity of the geometric parameters of the support system was analyzed as well. These parameters are ranked by their sensitivity from high to low, as is shown below: beam thickness, plastic zone width, room span, pillar width, and pillar height. Then, the goaf was classified according to the geometric parameters. Energy catastrophe theory was applied to analyze the stability of the support system in different classes of goaf. The analysis results showed that Class D goaf should be labeled as the unstable zone, which was consistent with the result of field research. To conclude, energy catastrophe theory can be used to demonstrate the nonlinear mechanical mechanism of support system instability in room-pillar mining goaf.

scholarly journals HYDRAULIC PARAMETERS OF THE BLOCK RAMP WITH RIDGE TYPE NOTCH: THE GRAJCAREK IN SZCZAWNICA, POLISH CARPATHIANS

2020 ◽  
Vol 19 (3) ◽  
pp. 43-58
Author(s):  
Karol Plesiński ◽  
◽  
Artur Radecki-Pawlik ◽  
Nadzieja Jurkowska ◽  
◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Numerical Modelling ◽  
Cross Sections ◽  
Water Movement ◽  
Field Research ◽  
Field Measurements ◽  
Hydraulic Jumps ◽  
The Stability ◽  
Hydrodynamic Data ◽  
Block Ramp

Aim of the study: The aim of this study is to analyze the hydrodynamic parameters in the area of one of the block ramp in the analyzed stream. Material and methods: The field research included geodetic measurements on the basis of which the longitudinal profile and cross-sections of the watercourse bed and structures were made. Numerical modelling of flood flows was also performed in the HEC-RAS program, from which hydrodynamic data were obtained. The data obtained from field measurements and numerical modelling were used to calculate the length of the energy dissipation basins of the structure and to determine the type of water movement using the Froude number. The calculations were performed for several variants. The real lengths of the energy dissipation basin were compared with the lengths of hydraulic jumps that are formed on them. Results and conclusions: The obtained results indicate that the length of the energy dissipation basin is too short because the hydraulic jumps go beyond them. As a result, a scour is formed below the structure, which in the event of further development may threaten the stability of the structure.

DEVELOPMENT OF THE BASIC CRITERIA FOR RUSSIAN COASTS TYPIFICATION

2017 ◽  
Author(s):  
Рубен Косян ◽  
Ruben Kosyan ◽  
Viacheslav Krylenko ◽  
Viacheslav Krylenko
Keyword(s):  
Coastal Zone ◽  
Coastal Area ◽  
Economic Activity ◽  
Basic Information ◽  
Dynamic Features ◽  
Static State ◽  
Evolutionary Features ◽  
Coastal Features ◽  
The Stability

There are many types of coasts classifications that indicate main coastal features. As a rule, the "static" state of the coasts is considered regardless of their evolutionary features and ways to further transformation. Since the most part of the coastal zone studies aimed at ensuring of economic activity, it is clear that the classification of coast types should indicate total information required by the users. Accordingly, the coast classification should include the criterion, characterizing as dynamic features of the coast and the conditions and opportunities of economic activity. The coast classification, of course, should be based on geomorphological coast typification. Similar typification has been developed by leading scientists from Russia and can be used with minimal modifications. The authors propose to add to basic information (geomorphological type of coast) the evaluative part for each coast sector. It will include the estimation of the coast changes probability and the complexity of the coast stabilization for economic activity. This method will allow to assess the dynamics of specific coastal sections and the processes intensity and, as a result – the stability of the coastal area.

Effect of Geometric Parameters of New Semisubmersible Platform on Stability and Hydrodynamic Performance

2021 ◽  
Author(s):  
Tianying Wang ◽  
Yanjun Zhou ◽  
Honglin Tang ◽  
Shihua Zhang ◽  
Haiqing Tian
Keyword(s):  
Geometric Parameters ◽  
Hydrodynamic Performance ◽  
Geometrical Parameters ◽  
Main Body ◽  
Floating Bodies ◽  
Full Picture ◽  
New Type ◽  
Design Plan ◽  
The Stability ◽  
Shape Characteristics

Abstract The JCSM concept (short for Jackup Combined Semisubmersible Multifunction Platform) is a new type of semisubmersible platform presented by the first author, which overcomes the shortcomings of the available semisubmersible platforms, and combines the advantages of the traditional semisubmersible platform, the Jackup platform and the new FPSO concept - IQFP. Due to the complicated interaction between stability and hydrodynamic performance, it is necessary to explore the effect of geometrical parameters of the main body on the stability and hydrodynamic performance in order to obtain the optimal design plan of a JCSM platform. Firstly, the structure components and innovations of the JCSM were briefly reviewed in order to facilitate readers to understand its full picture. Then, six independent geometric parameters were selected by carefully studying the shape characteristics of the initial design plan of a JCSM study case. Furthermore, the stability heights and motion responses of various floating bodies of the JCSM case with different geometric parameters in wave were calculated using boundary element method based on potential flow theory. Lastly, effect of the shape parameters on stability and hydrodynamic performance of the JCSM was qualitatively evaluated. The research would shed lights on the shape design of the JCSM main body.

Judgement Method for Surrounding Rock Stability of Guanjiao Tunnel Based on Catastrophe Theory

2011 ◽  
Vol 90-93 ◽  
pp. 2307-2312 ◽  
Author(s):  
Wen Jiang Li ◽  
Su Min Zhang ◽  
Xian Min Han
Keyword(s):  
Plastic Strain ◽  
Catastrophe Theory ◽  
Soft Rock ◽  
Surrounding Rock ◽  
In Situ Monitoring ◽  
Engineering Practice ◽  
Stability Of Surrounding Rock ◽  
The Stability ◽  
Rock Tunnel

The stability judgement of surrounding rock is one of the key jobs in tunnel engineering. Taking the Erlongdong fault bundle section of Guanjiao Tunnel as the background, the stability of surrounding rock during construction of soft rock tunnel was discussed preliminarily. Based on plastic strain catastrophe theory, and combining numerical results and in-situ data, the limit displacements for stability of surrounding rock were analyzed and obtained corresponding to the in-situ monitoring technology. It shows that the limit displacements obtained corresponds to engineering practice primarily. The plastic strain catastrophe theory under unloading condition provides new thought for ground stability of deep soft rock tunnel and can be good guidance and valuable reference to construction decision making and deformation managing of similar tunnels.

scholarly journals Literacy Culture Development through Class Library at SDIT Salsabila 2 Klaseman Ngaglik Sleman

2019 ◽  
Vol 11 (2) ◽  
pp. 183-203
Author(s):  
Ahmad Safi'i
Keyword(s):  
Life Skills ◽  
Human Life ◽  
School Library ◽  
Field Research ◽  
Class Library ◽  
Reduction Techniques ◽  
The Government ◽  
Using Data ◽  
The Stability ◽  
Culture Development

Life skills are proven to be able to improve human civilization.  Improving literacy culture is one way to develop human life skills.  The National Literacy Movement/ Gerakan Literasi Nasional (GLN) initiated by the government is an effort to realize it.  SDIT Salsabila 2 Klaseman has a Class Literacy Movement/ Gerakan Literasi Kelas (GLK) program.  The limited space available is not a reason to discourage GLK.  This type of research was case study field research.  The institution studied was SDIT Salsabila 2 Klaseman.  The subjects consisted teachers, principals, students and parents.  Data was obtained by observation, interviews and documentation steps.  Analysis was performed by using data reduction techniques, data display, triangulation, and conclusion drawing/verification.  The data showed that the main purpose of GLK was to intensify the culture of school literacy, library revitalization, and maintain the stability of school library functions.  The technical implementation is by creating a class library in each class, fostering a sense of belonging to the class library, supplying books from the school library to the class library, providing educational playgrounds in the area of the class library, giving rewards for students who are diligent in reading, achievements are informed in public, and explore the student guardian support. The problems that arise are the lack of teacher exemplariness, lack of consistency, supply of books from school libraries is still small, and the system of re-education has not been orderly.

Instabilities of a buoyancy-driven system

1969 ◽  
Vol 35 (4) ◽  
pp. 775-798 ◽  
Author(s):  
A. E. Gill ◽  
A. Davey
Keyword(s):  
Prandtl Number ◽  
Order Effects ◽  
Mechanical Instability ◽  
Rotating Fluids ◽  
First Order ◽  
Vertical Slot ◽  
Driven System ◽  
Prandtl Numbers ◽  
The Stability ◽  
Sommerfeld Equation

A buoyancy-driven system can be unstable due to two different mechanisms—one mechanical and the other involving buoyancy forces. The mechanical instability is of the type normally studied in connexion with the Orr-Sommerfeld equation. The buoyancy-driven instability is rather different and is related to the ‘Coriolis’-driven instability of rotating fluids. In this paper, the stability of a buoyancy-driven system, recently called a ‘buoyancy layer’, is examined for the whole range of Prandtl numbers, s. The buoyancy-driven instability becomes increasingly important as the Prandtl number is increased and so particular interest is attached to the limit in which the Prandtl number tends to infinity. In this limit, the system is neutrally stable to first order, but second-order effects render the flow unstable at a Reynolds number of order σ-½. Consequences of the results for the stability of convection in a vertical slot are examined.

scholarly journals On the alternative approaches to stability analysis in decision support for damaged passenger ships

2019 ◽  
Vol 18 (3) ◽  
pp. 477-494 ◽  
Author(s):  
Pekka Ruponen ◽  
Petri Pennanen ◽  
Teemu Manderbacka
Keyword(s):  
Decision Support ◽  
Stability Analysis ◽  
Decision Support System ◽  
Support System ◽  
Point Of View ◽  
Additional Information ◽  
Damage Stability ◽  
Passenger Ships ◽  
Minimum Requirements ◽  
The Stability

Abstract A decision support system with damage stability analysis has been recognized as an important tool for passenger ships. Various software applications have been developed and taken into use over the years, without a direct link to any compelling requirement, set forth in the international regulatory framework. After the Costa Concordia accident, new regulations have been established, setting minimum requirements for a decision support system, as an extension to a loading computer. Yet, more advanced systems have been developed recently, aiming at providing valuable additional information on the predicted development of the stability of the damaged ship. This paper presents these alternative decision support systems with damage stability analysis methods for flooding emergencies on passenger ships. The technical background, usability, and usefulness of the various approaches are compared and discussed, taking into account the important statutory approval point of view. In addition, practical examples, including past accidents, are presented and discussed.

scholarly journals Experimental Research on Mechanical and Energy Characteristics of Reinforced Rock under Dynamic Loading

2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Xinxi Liu ◽  
Yu Li ◽  
Fujun Zhao ◽  
Yanming Zhou ◽  
Weiwei Wang ◽  
...  
Keyword(s):  
Energy Dissipation ◽  
Strain Rate ◽  
Dynamic Loading ◽  
Split Hopkinson Pressure Bar ◽  
Dynamic Compression ◽  
Surrounding Rock ◽  
Absorbed Energy ◽  
Energy Characteristics ◽  
Deep Mining ◽  
The Stability

The properties of anchored surrounding rock may vary considerably under complex geological and stress conditions, especially dynamic loading in deep mining. Therefore, comprehensive study of the reinforced mechanism is required to prevent failures associated with deep mining. In this paper, with sandstone as matrix and steel bar as bolt, the dynamic compression test of reinforced rock was carried out by using a 50 mm rod diameter split Hopkinson pressure bar (SHPB) test device. The mechanical and energy characteristics of reinforced rock under dynamic loading were analyzed. The results show that the dynamic strength of reinforced sample is greater than that of unreinforced sample and increases with the increase of the strain rate. The reflected energy and absorbed energy increase with the increase of incident energy, while the transmitted energy increases slightly. The higher the strain rate, the larger the energy dissipation rate and the higher the degree of fragmentation. It shows that the energy dissipation characteristic reflects the internal damage process to some extent. Compared with the results of unreinforced samples, the reflected energy of reinforced samples significantly increases and the absorbed energy will significantly decrease. It can be seen that the bolt can reduce absorbed energy of surrounding rock, thereby improving the stability of roadway surrounding rock. The results may provide reference for the stability of deep roadway and support design.

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