scholarly journals Concept of workings reuse with application of resource-saving bolting systems

2019 ◽  
Vol 133 ◽  
pp. 02001 ◽  
Author(s):  
Volodymyr Bondarenko ◽  
Iryna Kovalevska ◽  
Oleksandr Husiev ◽  
Vasyl Snihur ◽  
Ildar Salieiev
Keyword(s):  
High Load ◽  
Resource Saving ◽  
Load Bearing Capacity ◽  
Resistance Level ◽  
Roof Bolting ◽  
Roof Bolts ◽  
Horizontal Thrust ◽  
Roof Rocks ◽  
Thrust Forces

The new support patterns have been revealed for controlling the combinations of the roof rocks strengthening processes in extraction mine workings with combined roof-bolting systems. It has been established that in adjacent roof rocks, by means of a combination of rope bolts and resin-grouted roof bolts, an armored and rock plate is formed, the high load-bearing capacity of which is achieved by maintaining the horizontal thrust forces that reduces the concentrations of all the stresses components to a level many times lower than the strength characteristics of the lithotypes. The criterion has been substantiated for assessing the resistance level of roof-bolts as a part of the combined roof-bolting system, which is used for determination of the most important geomechanical factors in terms of the system loading degree. The patterns have been established of a degree of loading the roof-bolts being a part of the combined roof-bolting system from the main influencing geomechanical factors. The calculated expressions have been obtained to determine the needed parameters for effectively strengthening the roof in workings by a combined roof-bolting system. The mine experiment analysis has been performed as well.

scholarly journals Constructing a biomimetic robust bi-layered hydrophilic lubrication coating on surface of silicone elastomer

Friction ◽  
2021 ◽  
Author(s):  
Luyao Gao ◽  
Xiaoduo Zhao ◽  
Shuanhong Ma ◽  
Zhengfeng Ma ◽  
Meirong Cai ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Composite Layer ◽  
High Load ◽  
Silicone Elastomer ◽  
Aqueous Lubrication ◽  
Low Friction ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Lubrication Performance ◽  
Wide Range

AbstractSilicone elastomers-based materials have been extensively involved in the field of biomedical devices, while their use is extremely restricted due to the poor surface lubricity and inherent hydrophobicity. This paper describes a novel strategy for generating a robust layered soft matter lubrication coating on the surface of the polydimethylsiloxane (PDMS) silicone elastomer, by entangling thick polyzwitterionic polyelectrolyte brush of poly (sulfobetaine methacrylate) (PSBMA) into the sub-surface of the initiator-embedded stiff hydrogel coating layer of P(AAm-co-AA-co-HEMA-Br)/Fe, to achieve a unified low friction and high load-bearing properties. Meanwhile, the stiff hydrogel layer with controllable thickness is covalently anchored on the surface of PDMS by adding iron powder to provide catalytic sites through surface catalytically initiated radical polymerization (SCIRP) method and provides high load-bearing capacity, while the topmost brush/hydrogel composite layer is highly effective for aqueous lubrication. Their synergy effects are capable of attaining low friction coefficient (COFs) under wide range of loaded condition in water environment with steel ball as sliding pair. Furthermore, the influence of mechanical modulus of the stiff hydrogel layer on the lubrication performance of layered coating is investigated, for which the COF is the lowest only when the modulus of the stiff hydrogel layer well matches the PDMS substrate. Surprisingly, the COF of the modified PDMS could remain low friction (COF < 0.05) stably after encountering 50,000 sliding cycles under 10 N load. Finally, the surface wear characterizations prove the robustness of the layered lubricating coating. This work provides a new route for engineering lubricious silicon elastomer with low friction, high load-bearing capacity, and considerable durability.

scholarly journals Determination of the neutralization depth of concrete under the aggressive environment influence

2018 ◽  
Vol 33 ◽  
pp. 02010 ◽  
Author(s):  
Anastasia Morzhukhina ◽  
Stanislav Nikitin ◽  
Elena Akimova
Keyword(s):  
Reinforced Concrete ◽  
Chloride Ions ◽  
The Body ◽  
Chemical Plants ◽  
Reinforced Concrete Structure ◽  
Load Bearing Capacity ◽  
High Rise ◽  
Capacity Loss ◽  
Air Penetration

Aggressive environments have a significant impact on destruction of many reinforced concrete structures, such as high-rise constructions or chemical plants. For example, some high-rise constructions are equipped with a swimming pool, so they are exposed to chloride ions in the air. Penetration of aggressive chemical substances into the body of concrete contributes to acceleration of reinforced concrete structure corrosion that in turn leads to load bearing capacity loss and destruction of the building. The article considers and analyzes the main technologies for calculating penetration depth of various aggressive substances into the body of concrete. The calculation of corrosion depth was made for 50-year service life.

scholarly journals Comparative study for designing the horizontal thrust blocks in pipelines for water and sewage networks

2021 ◽  
Author(s):  
Osama S. Hussien
Keyword(s):  
Drinking Water ◽  
Comparative Study ◽  
Thrust Force ◽  
Block Design ◽  
Surrounding Area ◽  
Design And Implementation ◽  
Horizontal Thrust ◽  
Bend Angles ◽  
Thrust Forces ◽  
Block Dimensions

Abstract The thrust block is one of the most widely recognized methods of resisting thrust forces. This type of infrastructure should be installed in bends, dead ends, tees and wyes. Thrust blocks perform the function of transferring thrust force to the ground safely. Thrust block dimensions are designed based on hydrostatic pressures, bend angles, and soil properties in the surrounding area. Several codes exist for designing thrust blocks, but we focus on Egyptian code for design and implementation of pipelines for drinking water and sewage networks (ECDIPWSN) and the American Water Works Association (AWWA). In this methodology, the steps of thrust block design by the codes are demonstrated and applied individually to one of the published papers. The goal of the study is to find the optimum percentages between the dimensions of the block in the two codes and to compare the quantity of concrete after the block is designed by each code. Based on the research, it was found that the concrete amount of the block designed by (AWWA) is smaller than that designed by (ECDIPWSN). HIGHLIGHT Results of the study discovered the volume of the thrust block created by the AWWA method was smaller than the volume created by the ECDIPWSN method when excavation depth was low but was larger when excavation depth was large.

Continuously Growing Ultrathick CrN Coating to Achieve High Load-Bearing Capacity and Good Tribological Property

2018 ◽  
Vol 10 (3) ◽  
pp. 2965-2975 ◽  
Author(s):  
Zechao Li ◽  
Yongxin Wang ◽  
Xiaoying Cheng ◽  
Zhixiang Zeng ◽  
Jinlong Li ◽  
...  
Keyword(s):  
Bearing Capacity ◽  
Tribological Property ◽  
High Load ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Crn Coating

Assessment of Load-Bearing Capacity of Bridges

2017 ◽  
Vol 259 ◽  
pp. 113-118 ◽  
Author(s):  
Jaroslav Navrátil ◽  
Michal Drahorád ◽  
Petr Ševčík
Keyword(s):  
Bearing Capacity ◽  
Prestressed Concrete ◽  
Iterative Solution ◽  
Concrete Bridges ◽  
Load Bearing Capacity ◽  
Load Bearing ◽  
Prestressed Concrete Bridges ◽  
Existing Structures ◽  
Non Linear

The paper aims to the determination of load-bearing capacity of reinforced/prestressed concrete bridges subjected to the combination of all components of internal forces according to Eurocode standards for assessment of existing structures. Undoubtedly bridge load rating is laborious hand-iterative process, especially when it comes to reinforced and/or prestressed concrete bridges. The engineer can spend days and weeks trials and errors in the estimation of bridge load-carrying capacity. The problem lies in the determination of load-bearing capacity of cross-section subjected to the combination of normal and shear forces, bending and torsional moments. Due to the different effects of permanent and variable loads and the non-linear behavior of structural materials, the problem becomes non-linear and its solution requires the use of suitable iterative method. Optimized iterative solution was implemented into IDEA StatiCa software and the results are presented in this paper.

scholarly journals Determination of Cr (VI) Content in Water-Soluble Dyes

2020 ◽  
Vol 59 (1) ◽  
pp. 88-94
Author(s):  
M P Sathianarayanan ◽  
Rina Nayak ◽  
Yogesh Hande
Keyword(s):  
Spectroscopic Analysis ◽  
Extraction Procedure ◽  
Cost Effective ◽  
High Load ◽  
Water Soluble ◽  
Recovery Study ◽  
Good Repeatability ◽  
Repeatability And Reproducibility ◽  
Standard Solution

Abstract Hexavalent chromium detection in the presence of high load of colorants is a challenge, and it is an important area of study. Colorants are a class of interfering substance in many spectroscopic analysis and chromatographic separation and detection. In this study, a method has been developed to separate out Cr (VI) and water-soluble dyes by using activated charcoal as an absorption medium. The extraction procedure was optimized with Cr (VI) standard solution for quantification. The efficacy of the extraction procedure for the removal of water-soluble dyes and detection of Cr (VI) was checked with a spike recovery study. Based on the spike recovery study, the method has been validated as per the international validation protocol. The method is simple, cost effective and has a detection limit down up to 3.0 mg/kg. The recovery rate of Cr (VI) in water-soluble dyes like reactive yellow HE 6G, reactive red 218, turquoise blue HGN, reactive navy blue RX and reactive black 5A was found to be more than 90% with a good repeatability and reproducibility.

A Study of Influence of the Machining Accuracy on Reliability of Cycloidal Gears

2020 ◽  
pp. 9-17
Author(s):  
Y.V. Sinitsyna
Keyword(s):  
Probability Of Failure ◽  
High Load ◽  
Maximum Effect ◽  
Machining Accuracy ◽  
Positional Error ◽  
Aircraft Industry ◽  
Load Bearing Capacity ◽  
The Monte Carlo Method ◽  
Manufacturing Errors ◽  
Fixed Period

Cycloidal gears are widely used in modern robotics, aircraft industry and other industries due to their compactness, high load bearing capacity, rigidity and accuracy. This paper examines a method for calculating stresses at the points of contact of the satellite gear and the pins taking into account manufacturing errors. Based on the Monte Carlo method, the probability of failure-free operation of the cycloid gear is determined by the criterion of contact endurance, taking into account the randomness of deviations of gear sizes from the nominal ones. Graphs showing the relationships between the probability of failure-free operation for a fixed period of time and the torque are presented. It is established that a 2kv gear has a higher reliability compared to the gear manufactured using the khv scheme. Based on the analysis of sensitivity of the failure-free operation probability to manufacturing errors, it is concluded that the positional error of the pin hole has the maximum effect on the gear performance.

Determination of roof bolting parameters for the space near the face in developing placer deposits with filling

1989 ◽  
Vol 25 (6) ◽  
pp. 569-572
Author(s):  
N. L. Kychkin ◽  
E. E. Petrov ◽  
V. Yu. Izakson ◽  
G. G. Sugarenko
Keyword(s):  
Roof Bolting ◽  
The Face ◽  
Placer Deposits
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