scholarly journals Research on Effects of Blast Casting Vibration and Vibration Absorption of Presplitting Blasting in Open Cast Mine

2016 ◽  
Vol 2016 ◽  
pp. 1-9 ◽  
Author(s):  
Li Ma ◽  
Kemin Li ◽  
Shuangshuang Xiao ◽  
Xiaohua Ding ◽  
Sydney Chinyanta
Keyword(s):  
Slope Stability ◽  
Blast Hole ◽  
Dynamic Loads ◽  
Blast Vibration ◽  
Detection Scheme ◽  
Stability Coefficient ◽  
Vibration Absorption ◽  
The Impact ◽  
Presplit Blasting ◽  
Blast Vibrations

The impact energy produced by blast casting is able to break and cast rocks, yet the strong vibration effects caused at the same time would threaten the safety of mines. Based on the theory of Janbu’s Limit Equilibrium Method (LEM), pseudo-static method has been incorporated to analyze the influence of dynamic loads of blasting on slope stability. The horizontal loads produced by blast vibrations cause an increase in sliding forces, and this leads to a lower slope stability coefficient. When the tensile stresses of the two adjacent blast holes are greater than the tensile strength of rock mass, the radical oriented cracks are formed, which is the precondition for the formation of presplit face. Thus, the formula for calculating the blast hole spacing of presplit blasting can be obtained. Based on the analysis of the principles of vibration tester and vibration pick-up in detecting blast vibrations, a detection scheme of blast vibration is worked out by taking the blast area with precrack rear and non-precrack side of the detection object. The detection and research results of blast vibration show that presplit blasting can reduce the attenuation coefficient of stress wave by half, and the vibration absorption ratio could reach 50.2%; the impact of dynamic loads on the end-wall slope stability coefficient is 1.98%, which proves that presplit blasting plays an important role in shock absorption of blast casting.

scholarly journals Stability conditions of the Vistula Valley attained by a multivariate approach – a case study from the Warsaw Southern Ring Road

Geologos ◽  
2015 ◽  
Vol 21 (4) ◽  
pp. 249-260 ◽  
Author(s):  
Łukasz Kaczmarek ◽  
Paweł Dobak
Keyword(s):  
Slope Stability ◽  
Road Traffic ◽  
Dynamic Loads ◽  
Ring Road ◽  
Load Factors ◽  
Geological Conditions ◽  
The Impact ◽  
Slope Design ◽  
Calculation Models

Abstract Localised landslide activity has been observed in the area of the plateau slope analysed, in the vicinity of the planned Warsaw Southern Ring Road. Using calculation models quantitative and qualitative evaluations of the impact of natural and anthropogenic load factors on slope stability (and hence, safety) are made. The present paper defines six stages of slope stability analysis, leading to an indication of optimum slope design in relation to the development planned. The proposed procedure produces a ranking of factors that affect slope stability. In the engineering geological conditions under consideration, the greatest factors impacting degradation and failure of slope stability are changes in soil strength due to local, periodic yielding and the presence of dynamic loads generated by intensification of road traffic. Calculation models were used to assess the impact of destabilisation factors and to obtain mutual equivalence with 3D-visualisation relations. Based on this methodology, various scenarios dedicated to specific engineering geological conditions can be developed and rapid stability evaluations of changing slope loads can be performed.

scholarly journals Application and Development of an Environmentally Friendly Blast Hole Plug for Underground Coal Mines

2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Donghui Yang ◽  
Yixin Zhao ◽  
Zhangxuan Ning ◽  
Zhaoheng Lv ◽  
Huafeng Luo
Keyword(s):  
Split Hopkinson Pressure Bar ◽  
Low Cost ◽  
Blast Hole ◽  
Environmentally Friendly ◽  
Test System ◽  
Industrial Test ◽  
Labor Intensity ◽  
Rock Blasting ◽  
Hopkinson Pressure Bar ◽  
The Impact

Drilling and blasting technology is one of the main methods for pressure relief in deep mining. The traditional method for blasting hole blockage with clay stemming has many problems, which include a large volume of transportation, excess loading time, and high labor intensity. An environmentally friendly blast hole plug was designed and developed. This method is cheap, closely blocks the hole, is quickly loaded, and is convenient for transportation. The impact test on the plug was carried out using an improved split Hopkinson pressure bar test system, and the industrial test was carried out in underground tunnel of coal mine. The tests results showed that, compared with clay stemming, the new method proposed in this paper could prolong the action time of the detonation gas, prevent premature detonation gas emissions, reduce the unit consumption of explosives, improve the utilization ratio, reduce the labor intensity of workers, and improve the effect of rock blasting with low cost of rock breaking.

The Specific Characteristics of Shock and Blast Impacts on Construction Sites

2021 ◽  
pp. 81-88
Author(s):  
A.A. Komarov ◽  
Keyword(s):  
Dynamic Load ◽  
Static Load ◽  
Dynamic Loads ◽  
Potential Hazard ◽  
Construction Sites ◽  
Static Loads ◽  
Equivalent Static Loads ◽  
Plane Crash ◽  
Nuclear Plants ◽  
The Impact

The practices of hazardous and unique facilities’ construction imply that specific attention is paid to the issues of safety. Threats associated with crash impacts caused by moving cars or planes are considered. To ensure safety of these construction sites it is required to know the potential dynamic loads and their destructive capacity. This article considers the methodology of reducing dynamic loads associated with impacts caused by moving collapsing solids and blast loads to equivalent static loads. It is demonstrated that practically used methods of reduction of dynamic loads to static loads are based in schematization only of the positive phase of a dynamic load in a triangle forms are not always correct and true. The historical roots of this approach which is not correct nowadays are shown; such approach considered a detonation explosion as a source of dynamic load, including TNT and even a nuclear weapon. Application of the existing practices of reduction of dynamic load to static load for accidental explosions in the atmosphere that occur in deflagration mode with a significant vacuumization phase may cause crucial distortion of predicted loads for the construction sites. This circumstance may become a matter of specific importance at calculations of potential hazard of impacts and explosions in unique units — for instance, in the nuclear plants. The article considers a situation with a plane crash, the building structure load parameters generated at the impact caused by a plane impact and the following deflagration explosion of fuel vapors are determined.

scholarly journals The Specific Energy Modal Components of the Impact Dynamic Loads in a Solid

2015 ◽  
Vol 111 ◽  
pp. 556-560 ◽  
Author(s):  
Zhanna G. Mogilyuk ◽  
Mikhail S. Hlystunov ◽  
Valery I. Prokopiev
Keyword(s):  
Specific Energy ◽  
Dynamic Loads ◽  
The Impact

Aeroelastic Tailoring of Helicopter Blades

2013 ◽  
Author(s):  
Donatien Cornette ◽  
Benjamin Kerdreux ◽  
Yves Gourinat ◽  
Guilhem Michon
Keyword(s):  
Dynamic Behaviour ◽  
Vertical Shear ◽  
Dynamic Loads ◽  
Modal Approach ◽  
Aeroelastic Tailoring ◽  
Helicopter Blades ◽  
Shear Modification ◽  
Elastic Couplings ◽  
The Impact ◽  
Aerodynamic Lift

The dynamic loads transmitted from the rotor to the airframe are responsible for vibrations, discomfort and alternate stress of components. A new and promising way to minimize vibration is to reduce dynamic loads at their source by performing an aeroelastic optimization of the rotor. This optimization is done thanks to couplings between the flapwise-bending motion and the torsion motion. The impact of elastic couplings (composite anisotropy) on the blade dynamic behaviour and on dynamic loads are evaluated in this paper. Firstly, analytical results, based on a purely linear modal approach, are given to understand the influence of those couplings in terms of frequency placement, aerodynamic lift load and vertical shear modification. Then, those elastic couplings are introduced on a simplified but representative blade (homogeneous beam with constant chord) and results are presented.

scholarly journals Impact Coefficient Analysis of Curved Box Girder Bridge Based on Vehicle-Bridge Coupling

2022 ◽  
Vol 2022 ◽  
pp. 1-11
Author(s):  
Fei Guo ◽  
Heng Cai ◽  
Huifang Li
Keyword(s):  
Shear Force ◽  
Primary Beam ◽  
Dynamic Loads ◽  
Box Girder ◽  
Impact Coefficient ◽  
Force Impact ◽  
Girder Bridge ◽  
The Moment ◽  
The Impact ◽  
Load Weight

In the current vehicle-bridge dynamics research studies, displacement impact coefficients are often used to replace the moment and shear force impact coefficients, and the vehicle model is also simplified as a moving-load model without considering the contribution of vehicle stiffness and damping to the system in some concerned research studies, which cannot really reflect the mechanical behavior of the structures under vehicle dynamic loads. This paper presents a vehicle-bridge coupling model for the prediction of dynamic responses and impact coefficient of the long-span curved bending beam bridge. The element stiffness matrix and mass matrix of a curved box girder bridge with 9 freedom degrees are directly deduced based on the principle of virtual work and dynamic finite element theory. The vibration equations of vehicle-bridge coupling are established by introducing vehicle mode with 7 freedom degrees. The Newmark-β method is adopted to solve vibration response of the system under vehicle dynamic loads, and the influences of flatness of bridge surface, vehicle speed, load weight, and primary beam stiffness on the impact coefficient are comprehensively discussed. The results indicate that the impact coefficient presents a nonlinear increment as the flatness of bridge surface changes from good to terrible. The vehicle-bridge coupling system resonates when the vehicle speeds reach 60 km/h and 100 km/h. The moment design value will maximally increase by 2.89%, and the shear force design value will maximally decrease by 34.9% when replacing moment and shear force impact coefficients with the displacement impact coefficient for the section internal force design. The load weight has a little influence on the impact coefficient; the displacement and moment impact coefficients are decreased with an increase in primary beam stiffness, while the shear force impact coefficient is increased with an increase in primary beam stiffness. The theoretical results presented in this paper agree well with the ANSYS results.

scholarly journals Empirical Analysis of the Impact Strength of Textile Knitted Barrier Meshes

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Zbigniew Mikołajczyk ◽  
Beata Szałek ◽  
Katarzyna Pieklak
Keyword(s):  
Measurement Data ◽  
Test Stand ◽  
Dynamic Loads ◽  
Measuring System ◽  
Electronic Measuring ◽  
Computer Data ◽  
Analysis System ◽  
Data Analysis System ◽  
Dynamic Stress Distribution ◽  
The Impact

AbstractThe assumptions of instrumental methodology for measuring dynamic loads of knitted barrier meshes were defined. A test stand was built, original in terms of both mechanical construction and electronic measuring system, connected to a computer data analysis system. Maximum values of dynamic forces in the mesh fastening strings were determined. The correctness of the strain gauges construction and measurement data transmission systems was confirmed. Tests of multidirectional resistance to dynamic loads in the mesh fastening strings were carried out. The experiment involved dropping a ball with a mass of 5 kg and a diameter of 10 cm, from a height of 1 m and 2 m onto the mesh surface. The potential impact energy equaled Ep1 = 49.05 J and Ep2 = 98.1 J. The tests showed that the highest force values were observed for meshes with square-shaped a-jour structure, and for mesh with diamond-shaped a-jour geometry the force values were lower. A symmetrical forces distribution was observed in all the strings. The highest forces were recorded in the middle strings and the lowest in the outer ones. The conducted tests confirmed the correctness of the adopted constructional solutions of test stand for identification of dynamic stress distribution in mesh fastening strings. The developed method is a useful verification tool for numerical analysis of mechanical properties of barrier meshes.

scholarly journals An Energy-Based Safety Evaluation Index of Blast Vibration

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Mingsheng Zhao ◽  
Dong Huang ◽  
Maosen Cao ◽  
En-an Chi ◽  
Jun Liu ◽  
...  
Keyword(s):  
Seismic Waves ◽  
Failure Modes ◽  
Guizhou Province ◽  
Damage Potential ◽  
Blast Vibration ◽  
Restoring Force ◽  
Safety Criterion ◽  
Plastic Damage ◽  
Field Investigations ◽  
Blast Vibrations

The combined peak particle velocity (PPV) and frequency safety criterion for blast vibration is widely used in blasting engineering. However, some field investigations are inconsistent with this criterion. On the basis of field investigations, it is found that there are two failure modes of structures subjected to blasting seismic waves, that is, first-excursion failure and cumulative plastic damage failure. Moreover, the nature of structural responses under blast vibrations is a process of energy input, transformation, and dissipation. Therefore, an energy-based dual safety standard is proposed in this work to more comprehensively explain all failure modes of structures under blast vibrations. To this end, structures are simplified into elastic-plastic single degree of freedom (SDOF) systems with bilinear restoring force models, and energy responses of SDOF systems are then determined using theNewmark-βmethod. From the energy responses, the maximum instantaneous input energy and hysteretic energy are selected as the basis of the dual safety criterion, because they can reflect first-excursion failure and cumulative plastic damage failure, respectively. Finally, field investigations in a blasting site in Zunyi, Guizhou province, China, are used to prove that compared to the PPV-frequency criterion the proposed energy-based dual safety criterion is more capable of assessing the damage potential of blast vibrations.

Numerical Analysis on the Response of Deck Plates Laterally Impacted by a Rectangular Indenter

2018 ◽  
Author(s):  
Ling Zhu ◽  
Junying Gao ◽  
Yinggang Li
Keyword(s):  
Permanent Deformation ◽  
Dynamic Loads ◽  
Parametric Studies ◽  
Ice Floes ◽  
Maximum Impact Force ◽  
Impact Energies ◽  
The Impact ◽  
Deformation Modes ◽  
Theoretical Procedure ◽  
Good Agreement

Ship deck plates are often subjected to localized dynamic loads, such as the loads of landing helicopter or impacts of ice floes. In order to investigate the dynamic response of ship plates subjected to such dynamic loads, a series of numerical simulations are performed on ship plates with different thicknesses. Parametric studies are performed on the impact response of plates, including the thickness of the plates, mass and impact velocity of the rectangular indenter. The maximum permanent deflections of the plates are obtained during the simulation. The relation between maximum force and permanent deflection is obtained and the deformation modes are analyzed. A theoretical procedure is developed to predict the deformation of plates with different initial impact energies, and a good agreement between the theoretical and numerical results is obtained. It has also been observed that the thickness of plates has little effect on the dimensionless maximum permanent deformation and dimensionless maximum impact force.

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