scholarly journals The Change of the Spatial Parameters of the Destruction of the Rock mass by Borehole Charge with Low-Density Tamping

2018 ◽  
Vol 41 ◽  
pp. 01018
Author(s):  
Igor Katanov
Keyword(s):  
Rock Mass ◽  
Mass Velocity ◽  
Specific Impulse ◽  
Low Density ◽  
Detonation Products ◽  
Impact Time ◽  
Borehole Charge ◽  
Theoretical Reasoning ◽  
Spatial Parameters ◽  
The Impact

Explosive destruction of the rock formation is substantiated by several theories developed by well-known scientists. The improvement of quality of preparation of rock mass to excavation, by an excavator without an increase in the value of specific consumption of explosives is important in the present time. Traditionally, to increase the impact time of detonation products on the rock hard tamping was used. The problem is in the rational redistribution of the explosion energy due to the use of a borehole charge, and in particular, in the tamping of low-density, porous materials. The more intensive attenuation of the mass velocity of particles in the material of such tamping in comparison with the mass velocity of the rock mass particles contributes to the well channel compression and increases the impact time of detonation products on the rock mass. As a result of redistribution of energy of detonation products, the specific impulse of explosion increases. The value of the radius of the controlled crushing zone increases by more than 1.6 times. The results of industrial explosions in coal mines have confirmed the theoretical reasoning.

scholarly journals Windblown Sand-Induced Degradation of Glass Panels in Curtain Walls

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 607
Author(s):  
Yuxi Zhao ◽  
Rongcheng Liu ◽  
Fan Yan ◽  
Dawei Zhang ◽  
Junjin Liu
Keyword(s):  
Visible Light ◽  
Mass Loss ◽  
Effective Area ◽  
Area Ratio ◽  
Light Transmittance ◽  
Relative Mass ◽  
Impact Time ◽  
Windblown Sand ◽  
Glass Panels ◽  
The Impact

The windblown sand-induced degradation of glass panels influences the serviceability and safety of these panels. In this study, the degradation of glass panels subject to windblown sand with different impact velocities and impact angles was studied based on a sandblasting test simulating a sandstorm. After the glass panels were degraded by windblown sand, the surface morphology of the damaged glass panels was observed using scanning electron microscopy, and three damage modes were found: a cutting mode, smash mode, and plastic deformation mode. The mass loss, visible light transmittance, and effective area ratio values of the glass samples were then measured to evaluate the effects of the windblown sand on the panels. The results indicate that, at high abrasive feed rates, the relative mass loss of the glass samples decreases initially and then remains steady with increases in impact time, whereas it increases first and then decreases with an increase in impact angle such as that for ductile materials. Both visible light transmittance and effective area ratio decrease with increases in the impact time and velocities. There exists a positive linear relationship between the visible light transmittance and effective area ratio.

scholarly journals Multi-platform app-embedded model for hybrid air-breathing rocket-cycle engine in hypersonic atmospheric ascent

2021 ◽  
pp. 1-23
Author(s):  
S.E. Tsentis ◽  
V.G. Gkoutzamanis ◽  
A.D. Gaitanis ◽  
A.I. Kalfas
Keyword(s):  
Specific Impulse ◽  
Performance Parameters ◽  
Interested Reader ◽  
Component Level ◽  
Air Breathing ◽  
Evaluation Of Performance ◽  
Embedded Model ◽  
The Impact ◽  
Rocket Technology ◽  
Engine Concept

ABSTRACT This paper presents a performance analysis on a novel engine concept, currently under development, in order to achieve hybrid air-breathing rocket technology. A component-level approach has been developed to simulate the performance of the engine at Mach 5, and the thermodynamic interaction of the different working fluids has been analysed. The bypass ramjet duct has also been included in the model. This facilitates the improved evaluation of performance parameters. The impact of ram drag induced by the intake of the engine has also been demonstrated. The whole model is introduced into a multi-platform application for aeroengine simulation to make it accessible to the interested reader. Results show that the bypass duct modelling increases the overall efficiency by approximately 7%. The model calculates the specific impulse at approximately 1800 seconds, which is 4 times higher than any chemical rocket.

scholarly journals The impact of drilling and slitting construction on damage field: evolution characteristics in low-permeability coal seam

2021 ◽  
Vol 37 ◽  
pp. 205-215
Author(s):  
Heng Chen ◽  
Hongmei Cheng ◽  
Aibin Xu ◽  
Yi Xue ◽  
Weihong Peng
Keyword(s):  
Finite Element ◽  
Rock Mass ◽  
Damage Mechanics ◽  
Effective Strain ◽  
Secondary Development ◽  
Distribution Area ◽  
Finite Element Program ◽  
Element Program ◽  
Mining Face ◽  
The Impact

ABSTRACT The fracture field of coal and rock mass is the main channel for gas migration and accumulation. Exploring the evolution law of fracture field of coal and rock mass under the condition of drilling and slitting construction has important theoretical significance for guiding efficient gas drainage. The generation and evolution process of coal and rock fissures is also the development and accumulation process of its damage. Therefore, based on damage mechanics and finite element theory, the mathematical model is established. The damage variable of coal mass is defined by effective strain, the elastoplastic damage constitutive equation is established and the secondary development of finite element program is completed by FORTRAN language. Using this program, the numerical simulation of drilling and slitting construction of the 15-14120 mining face of Pingdingshan No. 8 Mine is carried out, and the effects of different single borehole diameters, different kerf widths and different kerf heights on the distribution area of surrounding coal fracture field and the degree of damage are studied quantitatively. These provide a theoretical basis for the reasonable determination of the slitting and drilling arrangement parameters at the engineering site.

Study on Deformation and Damage of Rock Mass Subject to High In Situ Stress by Using a Elastoplastic Damage Model and Considering the Impact of Weak Planes

2013 ◽  
Vol 838-841 ◽  
pp. 705-709
Author(s):  
Yun Hao Yang ◽  
Ren Kun Wang
Keyword(s):  
Rock Mass ◽  
Large Scale ◽  
Damage Model ◽  
Back Analysis ◽  
In Situ Stress ◽  
Surrounding Rock ◽  
High In Situ Stress ◽  
Underground Caverns ◽  
The Impact

Large scale underground caverns are under construction in high in-situ stress field at Houziyan hydropower station. To investigate deformation and damage of surrounding rock mass, a elastoplastic orthotropic damage model capable of describing induced orthotropic damage and post-peak behavior of hard rock is used, together with a effective approach accounting for the presence of weak planes. Then a displacement based back analysis was conducted by using the measured deformation data from extensometers. The computed displacements are in good agreement with the measured ones at most of measurement points, which confirm the validities of constitutive model and numerical simulation model. The result of simulation shows that damage of surrounding rock mass is mainly dominated by the high in-situ stress rather than the weak planes and heavy damage occur at the cavern shoulders and side walls.

Analysis on the Impact Force of a Ship Colliding with a Bridge Pier

2012 ◽  
Vol 193-194 ◽  
pp. 693-701
Author(s):  
Jian Guo Ding ◽  
Zhi Qiao
Keyword(s):  
Mechanical Model ◽  
Mass Velocity ◽  
Impact Force ◽  
Impact Angle ◽  
Bridge Pier ◽  
Velocity Coefficient ◽  
The Impact

Because many accidents in China involve a ship in a barge fleet colliding with a bridge pier, determining the impact force of the ship is important. To obtain an equation that describes the impact force of a ship colliding with a bridge pier, a mechanical model of the collision is simplified, and the results from other researchers are applied. Based on the equation, it is found that the impact force of a ship colliding with a bridge pier is not only relevant to the mass，velocity, board thicknesses of the ship, and the impact angle, but also to the remaining velocity coefficient. It has been demonstrated that the result from the proposed equation in this paper is in accordance with that of Gkss’s test in Wosin G theory.

The impact of structural-tectonic of the rock mass on the formation and development of geo-deformation processes

2011 ◽  
pp. 2047-2051
Author(s):  
E Freiberg ◽  
E Bellendir ◽  
V Golitsyn ◽  
N Ablyamitov ◽  
E Cherkez ◽  
...  
Keyword(s):  
Rock Mass ◽  
Deformation Processes ◽  
The Impact

scholarly journals Evaluation of hydrated extract of phaseolus Vulgaris L. (bean plant) on hypoglycemia and hypolipidemic in streptozotocin-induced diabetic albino Wistar rats

2019 ◽  
Vol 10 (4) ◽  
pp. 3704-3710
Author(s):  
Helisha Ruth Obonyo ◽  
Senthemarai Selvi V
Keyword(s):  
Phaseolus Vulgaris ◽  
Blood Serum ◽  
Common Bean ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Diabetic Rats ◽  
Low Density ◽  
Phaseolus Vulgaris L ◽  
Reference Drug ◽  
The Impact

The current research was intended to comprehend hypoglycemic and anti-lipidaemic exercises of hydrated common bean (phaseolus Vulgaris L.) seed extracts on streptozotocin-induced diabetic albino rats. At a set portion fluctuate of 100, 200,300 mg/kg body weight of common bean extracts was orally directed as one portion for every day to polygenic disorder rats for a measure of thirty days. The impact of P.vulgaris L. on hypoglycemic, glycosylated hemoprotein (HbA1c) and blood serum lipid profile (Total cholesterin), Triglyceride (TG), very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), High-density lipoprotein (HDL)) in plasma were estimated in the regular and diabetic induced rat. The outcomes demonstrated that quick glucose,serum TC, TG, LDL, VLDL, levels were significantly (p<0.05) attenuate, while blood serum HDL, the level was extensively (p<0.05) upgraded inside the diabetic rats. The inconclusive amount of pace of 300 mg/kg is more reasonable than that of a hundred mg/kg. Our examination so shows that Phaseolus vulgaris L has a powerful adversary to diabetic and anti-lipidaemic impacts on streptozotocin-induced diabetic rats, and results were comparable to reference drug glibenclamide.

scholarly journals ANALISIS KEKUATAN TARIK DAN IMPAK MATERIAL KOMPOSIT POLIMER DALAM APLIKASI FIBERBOAT

2021 ◽  
Vol 4 ◽  
pp. 121-126
Author(s):  
Rezza Ruzuqi ◽  
Victor Danny Waas
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Composite Materials ◽  
Impact Strength ◽  
Metal Corrosion ◽  
Phase System ◽  
Low Density ◽  
Weight Percentage ◽  
Multi Phase ◽  
The Impact

Composite material is a material that has a multi-phase system composed of reinforcing materials and matrix materials. Causes the composite materials to have advantages in various ways such as low density, high mechanical properties, performance comparable to metal, corrosion resistance, and easy to fabricate. In the marine and fisheries industry, composite materials made from fiber reinforcement, especially fiberglass, have proven to be very special and popular in boat construction because they have the advantage of being chemically inert (both applied in general and marine environments), light, strong, easy to print, and price competitiveness. Thus in this study, tensile and impact methods were used to determine the mechanical properties of fiberglass polymer composite materials. Each test is carried out on variations in the amount of fiberglass laminate CSM 300, CSM 450 and WR 600 and variations in weight percentage 99.5% -0.5%, 99% -1%, 98.5% -1, 5%, 98% -2% and 97.5%-2.5% have been used. The results showed that the greater the number of laminates, the greater the impact strength, which was 413,712 MPa, and the more the percentage of hardener, the greater the impact strength, which was 416,487 MPa. The results showed that the more laminate the tensile strength increased, which was 87.054 MPa, and the more the percentage of hardener, the lower the tensile strength, which was 73.921 MPa.

scholarly journals Stability Assessment of Mining Excavations: the Impact of Large Depths

2018 ◽  
Vol 40 (3) ◽  
pp. 180-187
Author(s):  
Tadeusz Majcherczyk ◽  
Zbigniew Niedbalski ◽  
Łukasz Bednarek
Keyword(s):  
Rock Mass ◽  
In Situ Monitoring ◽  
Stability Assessment ◽  
Underground Excavations ◽  
Deformation Prediction ◽  
Large Depth ◽  
Coal Deposits ◽  
The Impact

AbstractBack in the early 1980s, coal deposits occurring at depths of ~700 m below surface were already regarded as large-depth deposits. Meanwhile, today the borderline depth of large-depth mining has extended to >1,000 m. Design, excavation and maintenance of mining roadways at the depth of >1,000 m have, therefore, become crucial issues in a practical perspective in recent years. Hence, it is now extremely important to intensify research studies on the influence of large depths on the behaviour of rock mass and deformation of support in underground excavations. The paper presents the results of the study carried out in five mining excavations at depths ranging from 950 to 1,290 m, where monitoring stations with measurement equipment were built. The analysis of data from laboratory and coal mine tests, as well as in situ monitoring, helped to formulate a set of criteria for stability assessment of underground excavations situated at large depths. The proposed methodology of load and deformation prediction in support systems of the excavations unaffected by exploitation is based on the criteria referring to the depth of excavation and the quality of rock mass. The depth parameter is determined by checking whether the analysed excavation lies below the critical depth, whereas the rock mass quality is determined on the basis of the roof lithology index (WL) and the crack intensity factor (n)

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