T.A. Averina1,2, K.A. Rybakov3 1Institute of Computational Mathematics and Mathematical Geophysics of Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia 3Moscow Aviation Institute (National Research University), Moscow, Russia
Keywords: stochastic differential equations, Euler-Maruyama method, Milstein method, Rosenbrock-type method, numerical method, rotational diffusion
This paper reviews recent publications that describe mathematical models with stochastic differential equations (SDEs) and applications in various fields. The purpose of this paper is to briefly describe Rosenbrock-type methods for approximate solution of SDEs. It shows how the performance of the numerical methods can be improved and the accuracy of calculations can be increased without increasing the implementation complexity too much. The paper also proposes a new Rosenbrock-type method for SDEs with multiplicative non-commutative noise. Its testing is carried out by modeling rotational diffusion.
A.V. Voytishek1, N.K. Shlimbetov2 1Institute of Computational Mathematics and Mathematical Geophysics of Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: computational nonparametric estimation of probability density for a given sample, computational functional kernel algorithm, computational functional projection algorithm, multi-dimensional analogue of frequency polygon, Strang-Fix approximation, multi-linear approximation, conditional optimization of computational functional algorithms
In this paper we formulate the requirements for choosing approximation bases in constructing cost-effective optimized computational (numerical) functional algorithms for approximating probability densities for a given sample, with special attention to stability and approximation of the bases. It is shown that to meet the requirements and construct efficient approaches to conditional optimization of the numerical schemes, the best choice is a multi-linear approximation and a corresponding special case for both kernel and projection computational algorithms for nonparametric density estimation, which is a multidimensional analogue of the frequency polygon.
S.A. Gusev1,2, V.N. Nikolaev3 1Institute of Computational Mathematics and Mathematical Geophysics of Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State Technical University, Novosibirsk, Russia 3Siberian Scientific Research Institute of Aviation named after S.A. Chaplygin, Novosibirsk, Russia
Keywords: heat transfer, boundary value problem, random disturbances, mathematical modeling
The main goal of the work is to simulate heat transfer in structural elements of an aircraft under random temperature changes on its outer surface due to rapid changes in environmental parameters. In this case, to model the heat transfer a one-dimensional boundary value problem of the third kind is taken for the heat conduction equation. Random disturbances are specified at the boundary corresponding to the outer surface. The numerical solution is based on an application of the Galerkin method. Modeling the random disturbances of the external environment is carried out using a Wiener integral in a system of differential equations written in integral form. Calculations for a problem with a known exact solution show that when moving away from the boundary with random disturbances, the numerical solution of the boundary value problem with disturbances converges to the known exact solution of the unperturbed boundary value problem. Based on an expansion of the solution to the boundary value problem in trigonometric functions, theoretical estimates are obtained for the influence of a disturbance on the outer surface as a function of the wall thickness and the disturbance magnitude.
B.A. Kargin1, E.G.I. Kablukova1, Q. Mu2, S.M. Prigarin1,3 1Institute of Computational Mathematics and Mathematical Geophysics of Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia 2MSU-BIT University, Shenzhen, China 3Novosibirsk State University, Novosibirsk, Russia
Keywords: radiation transfer, Monte Carlo method, cirrus clouds, geometrical optics
The paper deals with numerical models related to radiation transfer in ice clouds. A mathematical model of crystal particles of irregular shape and an algorithm for modeling such particles based on constructing a convex hull of a set of random points are considered. Two approaches to simulating radiation transfer in optically anisotropic clouds are studied. One approach uses pre-calculated scattering phase functions for crystals of various shapes and orientations. In the other approach, no knowledge of the phase functions is required; the radiation scattering angle is modeled directly in the interaction of a photon with crystal faces. This approach makes it possible to simply adjust the input parameters of the problem to changing microphysical characteristics of the environment, including shape, orientation, transparency of particles and roughness of their boundaries, and does not require time-consuming preliminary calculations. The impact of flutter on radiation transfer by a cloud layer and angular distributions of reflected and transmitted radiation are studied.
G.A. Michailov1,2, G.Z. Lotova1,2, I.N. Medvedev1,2 1Institute of Computational Mathematics and Mathematical Geophysics of Siberian Branch of Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: numerical statistical modeling, random medium, Voronoi tessellation, maximum cross-section method (Woodcock tracking), correlation randomized algorithms, grid approximation, particle flow, overexponential asymptotics, estimation error, computation cost
The paper presents efficiently realized approximations of random functions, which are developed by the authors and numerically modeled for the study of stochastic processes of particle transport, including criticality fluctuations of processes in random media with multiplication. Efficient correlation randomized algorithms for approximating an ensemble of particle trajectories using the correlation function or only the correlation scale of a medium are constructed. A simple grid model of an isotropic random field is formulated reproducing a given average correlation length, which ensures high accuracy in solving stochastic transfer problems for a small correlation scale. The algorithms are tested by solving a test problem of photon transfer and a problem of estimating the overexponential average particle flux in a random medium with multiplication.
V. A. Bunev
Voevodsky Institute of Chemical Kinetics and Combustion, Siberian Branch, Russian Academy of Science, Novosibirsk, Russia
Keywords: dimethyl ether, nitrogen, carbon oxides, flammability limits, super-equilibrium flame temperatures
Numerical simulation has shown that the effect of CO addition in small quantities to rich dimethyl ether mixtures is due only to the physical contribution to the normal flame speed. There is no chemical contribution. Therefore, extrapolation of linear regions of the dependences of rich flammability limits to zero concentrations of nitrogen, CO2, and CO gives the same value of the dimethyl ether concentration. The relationship between the chemical and physical contributions of the effect of a fixed CO additive was obtained over the entire range of dimethyl ether concentration in the mixture with air. The addition of CO affects the occurrence of superadiabatic temperatures in the dimethyl ether flame in the same ways as the addition of inert CO2 and N2.
K. Ya. Troshin1, A. A. Belyaev1, A. V. Arutyunov1,2, V. S. Arutyunov1,3 1N. N. Semenov Federal Research Center for Chemical Physics Russian Academy of Sciences, Moscow, Russia 2Shenzhen MSU-BIT University, Shenzhen, China 3Federal Research Center of Problems of Chemical Physics and Medicinal Chemistry of the Russian Academy of Sciences, Chernogolovka, Russia
Keywords: methane, carbon monoxide, ignition delay, kinetic modeling
Experimental studies and kinetic analysis of ignition in air of stoichiometric mixtures of methane with carbon monoxide at temperatures below 1000 K and pressures of 1-15 atm showed the complex nature of the influence of mixture composition, temperature and pressure on the ignition delay. For mixtures with different carbon monoxide contents, pressure has different effects on ignition, and the values of the effective ignition delay energy of these mixtures are very different, indicating serious changes in the process mechanism when changing all the above parameters. The most obvious changes are associated with the influence of these parameters on the formation reactions and subsequent kinetics of hydroperoxide radicals HO2•, including the role of their interaction with carbon monoxide. It is also necessary to take into account the contribution of highly exothermic processes involving carbon monoxide to the heat balance of the ignition process of such mixtures. Information on the influence of the main parameters on the ignition of mixtures of methane with carbon monoxide at low temperatures is necessary to ensure the safety of technological processes for the production and use of synthesis gas and hydrogen, the operation of coal mines, as well as the optimization of detailed kinetic mechanisms of the oxidation of light hydrocarbons.
B. S. Seplyarskii, R. A. Kochetkov, T. G. Lisina
Merzhanov Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, Chernogolovka, Russia
Keywords: SHS, combustion models, powder mixtures, titanium particle size, granules, impurity gas release.
For the first time, experimental dependences of the combustion rate of powder and granular mixtures 5Ti + 3Si, Ti + Cam, (Ti + Cam) + 20% Cu, (Ti + Cam) + 20% Ni, Ti + Ccr (with amorphous carbon in the form of soot and crystalline carbon in the form of graphite) on the size of titanium particles are discussed using different models of combustion front propagation in a condensed medium. The theory of gasless combustion (taking into account the mechanism of capillary spreading and without it), microheterogeneous models do not even qualitatively explain the difference in the dependences of the combustion rate on the size of titanium particles for powder mixtures of titanium with soot and with graphite or the increase in the combustion rate of powder mixtures Ti + Cam when diluted with nickel and copper, accompanied by a decrease in combustion temperature. Changing the structure of the medium – granulation of powder mixtures – leads to a change in the combustion rate without changing the phase composition of the synthesis products. Within the framework of the convective-conductive combustion model, all these results are explained uniformly by the inhibitory influence of impurity gases released ahead of the combustion front in powder mixtures when the conditions for heating the component particles are met. The influence of impurity gas release on the combustion rate of powder mixtures can be assessed for each composition by the difference in the combustion rates of granular and powder samples. For all studied compositions of granular mixtures, where the influence of impurity gases on the combustion rate is leveled, the analytical approximation of the experimental dependence of the combustion rate on the size of titanium particles showed qualitative agreement with the dependence that follows from the convective-conductive combustion model.
A. A. Syrovaten, I. A. Bedarev, D. A. Tropin
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: ignition, combustion, boron particles, PSU combustion model of boron, numerical simulation
A physico-mathematical model and a computational method have been developed to model the ignition and combustion of a suspension of boron particles in an oxidizer gas behind shock waves of varying intensity. Calculations were carried out for particles with a diameter of 1-20 μm at their volumetric concentrations m2 = 10-4 and 10-5, corresponding to a lightly dusty medium. Oxygen and a mixture of oxygen and water vapor at a mass concentration of water vapor of 10- 90% were considered as an oxidizer. The the structure of combustion waves was examined, and the behavior of the main parameters of the gas and particles was described. The influence of water vapor on the ignition delay time and burning time of boron particles was analyzed. The results were compared with experimental data available in the literature, and agreement on the ignition delay time at a surrounding gas temperature of 2200-3000 K was obtained.
A. M. Astakhov1, D. B. Lempert2 1Reshetnev Siberian State University of Science and Technology, Krasnoyarsk, Russia 2Federal Research Center for Problems of Chemical Physics and Medical Chemistry, Russian Academy of Sciences, Chernogolovka, Russia
Keywords: nitrohydrazine, ammonium dinitramide, solid composite propellant, specific impulse, effective impulse, combustion temperature, two-phase impulse loss
The energy capabilities of a hypothetical zwitterionic nitrohydrazine H3N+N-NO2 as a component of solid composite propellants are estimated. Two-component compositions with a hydrocarbon or active binder and three-component compositions with the addition of aluminum or aluminum hydride are considered. Compositions with an active binder and aluminum hydride show the highest calculated ballistic efficiency. Their specific impulse exceeds 280 s, and with allowance for two-phase losses, the maximum effective impulse of the third stage rocket motor, it reaches 265.4 s, whereas for an optimized similar composition based on ammonium dinitramide, this value is significantly lower (262.5 s).
A. A. Kotomin, S. A. Dushenok, A. S. Kozlov
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Keywords: solid explosives, liquid explosives, mixtures and solutions of explosives, nitromethane, suspensions, detonability, critical detonation diameter, specific surface
The detonability of mixtures of solid and liquid explosives (explosive suspensions) has been little studied, although they are part of plastisol and paste explosive compositions widely used in practice. In this work, the critical detonation diameters of suspensions of PETN, RDX, HMX, and FOX-7 os various dispersion (specific surface area 350-7000 cm2/g) in nitromethane. The content of crystalline explosives in suspensions was 3-60 wt.%. Suspensions were prepared using a vibrovacuum method. The sedimentation stability and homogeneity of suspensions was ensured by their thickening with a small addition of aerosil (2.0-2.5%). Charges of suspensions were prepared in thin-walled polyethyleneterephthalate tubes of various diameter. Thus, the critical detonation diameter of explosive suspensions was determined in fact for charges without a shell. The dependences of the critical detonation diameter of suspensions on the volume fraction of solid explosives have the same S-shaped form. The effect of the dispersion of explosives on these dependences was shown. Obtained dependences for suspensions of solid explosives in nitromethane were compared with similar experimental dependences for other explosive systems: solutions of liquid explosives in nitromethane; solutions of solid explosives in nitromethane; binary mixtures of finely dispersed solid explosives; binary mixtures of coarsely and finely dispersed explosives; compositions containing mixtures of coarsely and finely dispersed explosives and inert binder. It is shown that the dependences for binary mixtures of coarsely and micron-size explosives and compositions based on these mixtures (distinct heterogeneous systems) the same form as for suspensions.
Y.-H. Liu1,2, L. Bao3,4, H.-Z. Wang3,4, B.-Q. Xin1,2, A.-F. Yu3,4, C.-T. Ge1,2 1SINOPEC Research Institute of Safety Engineering Co., Qingdao, China 2SINOPEC National Petrochemical Project Risk Assessment Technical Center Co., Ltd, Qingdao, China 3SINOPEC Research Institute of Safety Engineering Co., Ltd, Qingdao, China 4State Key Laboratory of Safety and Control for Chemicals, Qingdao, China
Keywords: hydrogenation unit, hydrogen cloud explosion, FLACS, flame propagation law, antiknock engineering transformation
During the operation of a hydrogenation unit, there is the danger of leakage and explosion of high-pressure hydrogen. In order to study the evolution of the flame and shock wave in hydrogen explosion accidents, the explosion process and the impact range of hydrogen leakage in the hydrogenation unit are simulated based on the FLACS simulation software. First, we have established a high-precision three-dimensional physical model for the hydrogenation unit and investigated the influence of different equivalence ratio (ER) on the overpressure of the hydrogen cloud explosion. The result shows that, at ER= 0.8-1.4, the peak temperature, flame propagation velocity, and overpressure peak value generated by the hydrogen cloud explosion increase first and then decrease with an increase in the equivalence ratio. At ER = 1.05, the peak temperature and overpressure after the explosion have the largest values, and the flame propagation velocity at this time is 38.2 and 31.7% higher than that at ER = 0.8 and 1.4, respectively. At the same time, flame acceleration during its propagation can effectively promote an increase in the explosion overpressure inside the flame. In addition, the simulation results of this paper also provide theoretical guidance for the antiknock engineering transformation of chemical plant buildings.
A. A. Vasil'ev1,2, V. A. Vasiliev1 1Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: hydrogen power engineering, explosion hazard, ignition delay, kinetic data on detonation, fuel-oxygen mixture (FOM), fuel-air mixture (FAM)
A large pool of data on the detonation hazard of hydrogen in mixtures with oxygen and air in the range of concentrations from the lean to rich limit with variations of the initial pressure and temperature (individually or jointly) are reported. The most important parameter is the critical energy of detonation initiation, which serves as a measure of the explosion hazard of combustible systems: the smaller the value of this parameter, the more hazardous the mixture. The number of reliable measurements of the critical energy of detonation initiation in scientific publications is rather limited (which is even more true for waves with different symmetries) owing both to difficulties in measuring this parameter and to imperfection of mathematical models of energy transfer from the external booster to the combustible mixture.
A. A. Vasil'ev1,2, V. A. Vasiliev1 1Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk State University, Novosibirsk, Russia
Keywords: hydrogen power engineering, safety of atomic power plants, ignition delay, kinetic data on detonation, fuel-oxygen mixture (FOM), fuel-air mixture (FAM)
A large pool of data on the detonation hazard of hydrogen in mixtures with oxygen and air additionally diluted by inert gases and in the presence of steam in the mixture are reported. The most important parameter is the critical energy of detonation initiation, which serves as a measure of the explosion hazard of combustible systems: the smaller the critical energy, the more hazardous the mixture. The number of reliable measurements of the critical energy of detonation initiation in scientific publications is rather limited (which is even more true for waves with different symmetries).
T. A. Khmel, S. A. Lavruk
Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: hybrid detonation, hydrogen-oxygen mixture, aluminum particles, cellular structures, numerical modeling
A physical and mathematical model of hybrid detonation in a mixture of hydrogen - oxygen - argon with additives of microdispersed aluminum particles is presented. The combustion of hydrogen and aluminum is described within the framework of the given kinetics. The combustion reaction of aluminum takes into account the formation of suboxides and particles of solid aluminum oxide. Using numerical simulation methods of two-dimensional flows in a flat channel 10 cm wide, the processes of formation and propagation of cellular detonation in a mixture of 0.72H2 + O2 + 2.58Ar at an initial pressure of 0.26 atm with additions of aluminum particles of size 3.5 were studied. and 5 μm. The properties of regularization and reduction of cell size, an increase in front velocity, peak pressures and temperatures in the hybrid mixture in comparison with gas detonation have been established. Two-front regimes have been obtained that exist for a limited time. After the fronts merge, detonation accelerates and transitions to a fine-cell structure. The relationship between cell size and average detonation velocity is similar to the formula for overcompressed gas detonation.
F. A. Bykovskii, S. A. Zhdan, E. F. Vedernikov
Lavrentyev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: continuous multifront detonation, fuel-water emulsions, kerosene, hot air, transverse detonation waves, annular combustor
Regimes of continuous multifront detonation of a fuel-water emulsion (kerosene TS-1 - water) mixed with hot air preheated by a firing method in the settling chamber from 600 to 1200 K in a flow-type annular combustor 503 mm in diameter are obtained and studied. Regimes with one and two pairs of colliding waves are observed in the range of specific flow rates of air through the slot 600-1400 kg/(s·m2) for the equivalence ratio varied from 0.53 to 1.0. The frequency of rotation of transverse detonation waves is 1.0 ± 0.1 kHz for one pair of detonation waves and 2.4 ± 0.2 kHz for two pairs of detonation waves. For air temperatures up to 800 K, the limits of regimes of continuous multifront detonation are determined in terms of the mass fraction of water in kerosene: 0.38-0.53. It is shown that an increase in the water content in the fuel-water emulsion reduces the degree of dissociation of detonation products. At high air temperatures (1200 К), the specific impulse increases and approaches 2150 s if the impulse of cold species (with no combustion) is taken into account.
E. S. Prokhorov
Lavrent'ev Institute of Hydrodynamics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: explosion, detonation, chemical equilibrium, gas suspension, carbon, coal
This paper presents the results of calculation of the detonation of a homogeneous gas suspension of ultrafine carbon particles with an oxidizer (oxygen or air) assuming chemical equilibrium in the products of detonation combustion. The influence of the mass fraction of carbon in such mixtures on the velocity of the detonation front and the main gas-dynamic parameters of combustion products was studied numerically. The calculation results correlate with available experimental data on detonation velocity in a suspension of coal particles in oxygen and air.
Zh. A. Kostoreva, A. A. Kostoreva, D. Yu. Malyshev, S. V. Syrodoi
Tomsk Polytechnic University, Tomsk, Russia
Keywords: wood particle, biomass, ignition, ignition delay time, ignition mechanism
The influence of the moisture content of woody biomass on the mechanisms of its ignition and combustion. Research was carried out on an experimental setup under conditions corresponding in temperature to the combustion chamber of typical boiler units (873-1273 K). It was found that ignition occurred in the gas phase at a distance depending on the ambient temperature. The higher the air temperature, the larger the distance from the particle surface to the combustion zone of gaseous pyrolysis products of wood. Based on the results of experiments, the influence of the type of woody biomass on the characteristics and conditions of ignition of fuel particles was established. An analysis of the influence of wood fiber orientation in space relative to the direction of the heat flux vector on the ignition characteristics and conditions.
D. P. Kasymov, V. V. Perminov, E. N. Golubnichii, A. S. Yakimov
Tomsk State University, Tomsk, Russia
Keywords: wood, heated particles, combustion, ignition, conjugate heat transfer
A numerical simulation of the ignition of a structure made of wood material by a set of “hot” particles was performed. The problem is considered in Cartesian coordinates in a three-dimensional formulation. It was found that the ignition of the initial reagent is determined by the processes of heat exchange with the fire, drying, pyrolysis of dry wood, and oxidation reactions of carbon monoxide, methane and hydrogen. The dependences of the ignition delay time of wood material on the initial temperatures of the reagent, heated particles and the number of “hot” particles at which ignition conditions are realized have been established. A qualitative comparison of the calculation results with known data is provided.
V. N. Oparin
Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Experimental and theoretical research, physics and geomechanics of rock failure source zones, fire- and rockburst safety, geomechanical and geophysical energy emission events, integrated geoinformation and monitoring system, instrumental measurements, remote sensing, diagnostics, prediction, prevention, safety, stress-strain behavior, hydrocarbon-bearing formations
The article focuses on formulation and substantiation of a problem of safe subsoil management in view of the more and more difficult geological and climatic conditions, as well as growing depth and scale of mineral mining. It is shown that the current basic and applied research has created prerequisites for a successful solution of this problem. In Russia these prerequisites are connected with finding energy-based mechanisms of origination and growth of high-stress concentration and destruction zones in rock masses and geomaterials which feature a hierarchical block structure and many phases, and show properties of open self-organizing geosystems in the tectonic stress and strain field. Using advances in nonlinear geomechanics and geophysics, and cloud technologies of Big Data, a new methodology, technologies and software systems are developed for shaping a multilayer geoinformation and monitoring system for diagnostics, control and prediction of the industrial and ecological safety of mining regions in Russia.
Ronghuan Cai1, Yishan Pan1,2, Yonghui Xiao3, Feiyu Liu1 1Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines, Northeastern University, Shenyang, China 2Institute of Disaster Rock Mechanics, Liaoning University, Shenyang, China 3School of Physics, Liaoning University, Shenyang, China
Keywords: Coal-rock combination, loading rate, rock-coal strength ratio, mechanical properties, failure characteristics
In order to clarify the relationship between the mechanical properties of coal-rock composite and the loading rate and rock-coal strength ratio, uniaxial compression tests were carried out on coal-rock combinations with three different rock-coal strength ratios at four different loading rates. The rock-coal strength ratio λ is a ratio of the compression strength of rock to the compression strength of coal. The test results indicate that the relationship between the mechanical properties of coal-rock composite and loading rate is influenced by both the strong and weak components in the composite. The peak stress and elastic modulus mainly depend on the weak component, while the peak strain is determined by both the strong and weak components. For peak stress and elastic modulus, when the weak body is the same, the relationship with loading rate is the same, otherwise it is different. The relationship between the mechanical properties of coal-rock combination and λ is not affected by the loading rate. The weak body in the coal-rock combination is the main body of damage, and the greater the value of λ, the more severe the damage. At the same time, the failure mode shows a gradual transition from weak body failure inducing strong body failure to only weak body failure.
Wang Kaixing1,2, Wu Bin2, Pan Yishan2, A. P. Khmelinin3, A. I. Chanyshev3 1Ordos Research Institute, Liaoning Technical University, Ordos, China 2School of Mechanics and Engineering, Liaoning Technical University, Fuxin, China 3Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Block rock mass, fracture type effect on P-wave propagation in block model, time-frequency response analysis
This article experimentally investigates the characteristics of P-wave propagation in block rock mass when blocks fracture transversely and longitudinally. The velocity of P-wave, rock block acceleration, kinetic energy, displacement response, and the time-frequency response of rock block were analyzed. The results show that when the rock block fractures, the P-wave velocity decreases, the acceleration response duration time increases, and the maximum acceleration and kinetic energy decrease. However, transverse fractures show a more evident decrease in the acceleration and kinetic energy near the fracture area, and longitudinal fractures show a more evident decrease in the displacement amplitude far from the fracture area. On transverse fractures, the dominant frequency of acceleration and kinetic energy leads to a low value near the fracture area, but the dominant frequency of displacement-to a high value. Longitudinal fracture leads to a dominant frequency of block response occurrence time delayed far from the fracture area.
This article studied the biomechanical properties of salix root sampled from arid and semi-arid regions of China. The damage law of root in the process of stretching was analyzed by acoustic emission technique. The fractal dimension of root failure section was calculated by digital image processing technology. The results show that salix root tensile strength and ultimate elongation decreases with the diameter increasing, while ultimate tensile resistance and diameter are positively correlated. Damage variable characterized by cumulative AE energy can not only help research the rule of root damage quantitatively, but also allows determining the critical elongation when root became inactive. The optimal mining depth values are proposed, which enable reduction of ground surface deformation, elimination of root system damage, protection of planting on ground surface and, thus, decrease of possibility of bench convergence.
Yankui Hao1, Zhanguo Ma2, Zhongxiang Lin1, Wang Liu2, Peng Yue1, Junyu Sun2, Tao Chen2 1China Coal Geology Group Co. Ltd, Beijing, China 2School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou, China
Keywords: Rock deformation, grout injection, similarity-based simulation, coal mining, overburden deformation
Taking working face 8006 of a coal mine in North China as the engineering background, the contact stress of each rock stratum interface is calculated based on the principle of composite beam to predict the development position of the separation layer. The distributed fiber optic sensing technology monitors the horizons where the abscission develops. The test results can accurately reflect the deformation characteristics of the overlying strata in the field, which provides an important theoretical basis and guiding role for the design of the overlying strata grouting scheme in this coal mine. The results show that when the working face is fully mined, the separation layer is mainly developed between the coarse-grained sandstone and the lower sandy mudstone at a distance of 265 m from the coal seam roof. The grouting scheme is effective, which can provide a useful reference for similar grout injection in overburden separation projects.
A large number of cases of tunnel bottom deformation occur in nearly horizontally layered strata. This article analyzes the common characteristics of such tunnel bottom deformation through case studies, and introduces the limitations and requirements for bottom designs for China’s high-speed railway tunnels. The deformation mechanisms of the tunnel bottom were studied through the physical model experiment which revealed the interaction characteristics between the layered surrounding rock and the tunnel bottom structure. Through the numerical simulation study, the effect of different elevated arch curvatures on deformation of the tunnel bottom was investigated, and the effectiveness of elevation arch deepening in deformation control of the tunnel bottom was verified. The classified control countermeasures for deformation at the bottoms of the tunnels in nearly horizontally layered strata are provided.
In response to the engineering problem of severe damage to tunnels caused by coalburst, which leads to support failure and personnel casualties, a method of preventing coalburst through the support and energy-absorbing effects of supports has been proposed. An energy-absorbing hydraulic support is designed for circular or arched tunnels: it is called gantry energy-absorbing hydraulic support. The support mainly consists of three parts: an arched top beam, a micro-arc base, and an energy-absorbing hydraulic column. Through experiments, two types of the energy-absorbing components were compressed and tested. The results show that the average yield strength of a single anti-impact component is 1840 kN, and the energy absorption is 180 kJ when compressed by 100 mm. The average yield strength of the double section anti-impact component is 2460 kN, and the energy absorption is 410kJ when compressed by 100 mm. Both of these energy-absorbing components with a total energy absorption capacity of over 700 kJ are used in actual gantry energy-absorbing hydraulic support.
E. V. Denisova1, K. O. Sokolov2, A. P. Khmelinin1, A. I. Konurin1, D. V. Orlov1 1Chinakal Institute of Mining, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Chersky Institute of Mining of the North, Siberian Branch, Russian Academy of Sciences, Yakutsk, Russia
Keywords: Concrete lining, internal, rock mass, finite-difference time-domain method, electromagnetic properties, ground-penetrating radar
Ground-penetrating radar is used to study defects in the form of internal layers in concrete structures. It is found that modulus of deflection coefficient of GPR signals changes as function of the layer thickness and electromagnetic properties of the material filling the layer (sand, wet sand or air). The experimental and numerical research used the method of peak-to-peak amplitude ratio, which enabled determining the Fresnel coefficients for the upper and lower boundaries of a layer. The minimal layer thickness recorded by GPR was 2 mm.
A. A. Panzhin, N. A. Panzhina
Institute of Mining, Ural Branch, Russian Academy of Sciences, Ekaterinburg, Russia
Keywords: Modern geodynamic movements, rock mass, satellite geodesy, strain tensor, movement vector, monitoring, zoning
Movements and deformations of ground surface at the Almaz-Zhemchuzhina deposit are studied using surveying techniques. The source data in estimation of parameters and patterns of the stress-strain behavior were observations over the modern geodynamic movements using survey markers and GPS / GLONASS technologies. The proposed scientific approach and guidelines on the use of the studies of trend and cycling geodynamic movements made it possible to determine the natural stress-strain parameters and to accomplish zoning of the test area by the intensities of the movements.
Dewei Fan1,2, Aiwen Wang1,2,3, Yishan Pan1,2,3, Linghai Kong4, Shankun Zhao4, Kun Lv4 1Institute of Disaster Rock Mechanics, Liaoning University; Shenyang, China 2Environmental Engineering College, Liaoning University, Shenyang, China 3School of Mechanics and Engineering, Liaoning Technical University, Fuxin, China 4Coal Science and Technology Research Institute Co., Ltd, Beijing, China
Keywords: Coal samples, thermal-mechanical coupled loading, bursting proneness and energy release, fracture mode, coal mass
The spontaneous high-temperature conditions in deep mining cause significant changes in one of the factors that determine the risk of rock burst in coal mine roadways. Therefore, based on the test method of the bursting proneness of coal, uniaxial loading tests were conducted on coal specimens under different thermal loads to explore the variations in the bursting proneness and energy release of heated coal, analyze the variations and mechanism controlling the coal skeleton, physicochemical properties, quality, fracture mode evolution, and macrocrack quantity with different loading rates, and calculate and discuss the changes in the critical conditions of a coal-rock system during heating. In summаry, the study of the change in bursting energy release caused by the heating of coal can lay the foundation for the engineering-based prevention and control of composite dynamic disasters in deep coal mines.
Xu Lianman1, Leng Yuanhao1, Yang Fengshuo1, Li Hongbin2, Ma Yufei1, Li Na3, Wang Hongyang1, Yan Weiting1, Jiang Xinjian2 1School of Environment, Liaoning University, Shenyang, China 2Inner Mongolia Yitai Group Co., Ltd, Erdos, China 3School of Mechanics and Engineering, Liaoning Technical University, Fuxin, China
Keywords: Coal sample, energy absorption, borehole volume, simple free surface, rock burst, impact load
The energy absorption buffer test system is developed, the impact load compression test of single free face coal sample is carried out, and the digital speckle analysis technology is used to obtain the law of the influence of the hole rate, which is the volume of the borehole divided by the volume of the coal sample, on the energy absorption rate and deformation and failure characteristics of coal sample after drilling. The change of the drill layout of two and three holes in coal samples has little effect on the energy absorption performance. The complete coal sample is easy to form vertical main cracks, and the drilled coal sample first forms stress concentration near the borehole, and a large number of cracks appear. The multihole coal samples are easy to form cracks that make the boreholes connected, which converts more impact energy into surface energy and improves the energy absorption rate of coal samples.
S. D. Viktorov, V. M. Zakalinskii, I. E. Shipovskii, R. Ya. Mingazov
Academician Melnikov Research Institute of Comprehensive Exploitation of Mineral Resources-IPKON, Russian Academy of Sciences, Moscow, Russia
Keywords: Explosion, cluster charge, borehole charge design, mining problems, computer modeling, continuum mechanics, conservation laws, directed blasting
The authors put forward a look-ahead concept of science-based problem solving in deep-level mining. The issues of the problem realization and tooling are also addressed. A borehole charge is designed as a cluster of closed-spaced borehole charges to produce the directed blast effect by varying the cluster charge layout in a wide range. Using alternative technical capabilities of drilling, it is possible to variously redisperse the same equivalent energy in the single large-diameter borehole charge and in the cluster of smaller diameter borehole charges. The blast mechanism of the cluster charge pushes the limits of its application range and offers new approaches to problem solving in deep-level mining. Some technological aspects of geotechnologies are presented through the results of modeling the new approach to blast-induced impact using smooth particle hydrodynamics. Some tentative research findings inspire continuing with the study.
V. N. Odintsev1, V. V. Makarov2 1Academician Melnikov Research Institute of Comprehensive Exploitation of Mineral Resources-IPKON, Russian Academy of Sciences, Moscow, Russia 2Far Eastern Federal University, Vladivostok, Russia
Keywords: Rocks, micro structure, stress-strain behavior, mathematical model, cleavage fracture, crack, stability
This study proposes a mathematical fracture model including processes of fracture of structural bonds on micro scale (tens microns) and meso scale (millimeters and centimeters), as well as interaction of structural fragments on macro scale (fractures longer then tens centimeters). The model uses two geometrical criteria of fracture growth, connected with the structure of rocks and governing transition between structural scale. The problem on the stress-strain behavior of an elastic medium near a fracture at the change in the fracture length and in the scale of its influence is solved. The limit equilibrium of a fracture is analyzed. For a meso-scale fracture, such condition is unstable, and the fracture, therefore, develops dynamically and up to a macro scale. Sufficiently long macro fractures can grow in the mode of quasi statics due to independent advance of fracture tips.
a:2:{s:4:"TEXT";s:78:"M. V. Ryl’nikova, R. V. Berger, I. V. Yakovlev, V. I. Tatarnikov, P. O. Zubkov";s:4:"TYPE";s:4:"text";}
Academician Melnikov Research Institute of Comprehensive Exploitation of Mineral Resources-IPKON, Russian Academy of Sciences, Moscow, Russia
Keywords: Potash salt deposit, deep occurrence, extraction completeness, nonlinear deformation, consolidated backfill, backfill mixture, backfill technology, backfill material transport, logistics
To reduce intensity of deformation in rocks prone to buckling and plastic deformation, and sensitive to geo- and gas-dynamic phenomena, the authors propose a consolidated backfill technology using salt waste and processing reuse brine at the consumption limits of water-yielding capacity. A set of laboratory tests is carried out to find backfill mixtures adaptable to deep-level potash mining with estimation of deformation characteristics and strength properties of potash salt rocks. New principles and technologies of deep-level sylvinite extraction and backfill material transport by creating such geotechnical structures in stopes which ensure formation of consolidated backfill mass with the mined-out stope space factor close to one. This approach can enhance mine efficiency owing to increased extraction of sylvinite from rib and safety pillars.
This article uses XGBoost algorithm to calculate rock in-situ stress. By using Pearson correlation coefficient method, it is determined that the logging parameters with the best correlation with minimum horizontal principal stress are Depth, GR, LLD, ILD, AC, VCA, with maximum horizontal principal stress are: Depth, GR, SP, CAL, DEN. In order to verify the performance of the model, linear regression, support vector machine, and random forest models are used for comparison. In order to improve the generalization performance, the k-fold cross-validation method is used. The results show that using XGBoost algorithm to predict rock in-situ stress with a small amount of data has a high average accuracy of 94% and good generalization performance. The linear regression model has a faster fitting speed, but the fitting accuracy is the lowest. The random forest and support vector machine models are in-between. The result confirms that the research method in this article has certain universality and can be extended to solve other rock in-situ stress prediction problems.
A. V. Gireva1, O. M. Shabalina2, D. Yu. Pavlova1
a:2:{s:4:"TEXT";s:160:"1National Park «Krasnoyarskie Stolby», Krasnoyarsk, Russian Federation
2Siberian Federal University, Krasnoyarsk, Russian Federation";s:4:"TYPE";s:4:"html";}
Keywords: Abies sibirica Ledeb, annual growth, length and width of needles, meteorological conditions, Eastern and Western Sayan
The features of individual variability of morphometric characteristics of the shoot of Siberian fir ( Abies sibirica Ledeb.), growing at different altitudes on the northern macroslope of the Eastern Sayan in the territory of the Krasnoyarskie Stolby National Park, were studied. Siberian fir on the northern macroslope of the Eastern Sayan is found over the entire range of absolute heights - from low mountains to middle mountains. However, it was found as part of a tree stand in various forest types and does not demonstrate a strict phytocenotic association. Apparently, in this area, Siberian fir is in conditions of its ecological and phytocenotic optimum. The annual growth and leaf cover of the shoot varies at an average level, the length of the needles - mainly at a low level, the width of the needles - at a very low level. The length and width of needles, characterized by low variability, can be recommended for diagnostic purposes. A comparative analysis of the average values of the studied characteristics showed that as the absolute height increases, there is a statistically significant decrease in the annual growth, length and width of Siberian fir needles, as well as an increase in the shoot cover. Fir shoots from the Krasnoyarskie Stolby National Park (Eastern Sayan) are distinguished by higher values of annual growth, shoot cover and needle length, while the width of the needles is greater in fir from the Western Sayan. The observed differences may be associated not only with climatic differences in the regions, but also with different phytocenotic confinement of the studied cenopopulations. The annual growth of shoots and their cover significantly depend on the meteorological conditions of the year. A close correlation of these characteristics with the July temperature and air humidity in May and July is shown. There was no significant influence of weather conditions of the year on the morphometric characteristics of fir needles.
The formation of sustainable tree stands during timber harvesting in mature and overmature stands is largely determined by logging methods used and the technological methods for their implementation. In clear-cutting, this, first of all, depends on the degree of preservation of undergrowth, small size trees and trees that are not subject to felling, ensuring accelerated reproduction of stands in cleared areas. Among logging technologies, this is facilitated by narrow felling technological schemes with logging widths of 15-30 m, which allow maintaining undergrowth and undergrowth of over 60 %. In selective felling, the main emphasis is on the formation of valuable stands of a certain density, age and structure due to the intensity and uniformity of the selection of tree species, the preservation of forest growing environment and the growing conditions of the main forest-forming species. Here technologies can be used that allow for a uniform selection of trees over an area while maintaining post-harvesting density of at least 0.5. The goal of the study was to identify optimal techniques and methods of felling during timber harvesting, ensuring the formation of sustainable post-logging tree stands for the main forest formations of the Russian Far East.
Behavioral reactions that weaken the limiting influence of abiotic factors play an important role in achieving compliance of plant functioning with the environment. One of such adaptive reactions is the compensation (substitution) of the action of one factor by the influence of an other. It is known that with the deterioration of growing conditions, the proportion of the assimilation apparatus in the total phytomass increases, thereby compensating for its reduced activity in these conditions. In general, an increase in the density of needles on shoots increases the absorption coefficient of photosynthetically active radiation (PhAR) and reflects an increased compensatory ability in unfavorable abiotic conditions. The purpose of our study was to confirm or refute the hypothesis of factor compensation by the example of changes in the share of needles in shoots of Scots pine ( Pinus sylvestris L.) in the gradient of the sum of effective temperatures geographically distributed in Northern Eurasia. Based on the author’s database, which includes 490 definitions of the percentage of needles in the mass of shoots, a regression model of the dependence of needle percentage upon the age, stem diameter and the sum of effective temperatures is constructed, explaining 40 % of the variability of the desired indicator. An inversely proportional dependence of the percentage of needles in shoot phytonass on the sum of effective temperatures has been established. Thus, the hypothesis of compensation of the reduced sum of effective temperatures (and the corresponding PhAR) by an increase in the percentage of needles and the corresponding absorption coefficient of PhAR is confirmed.
Yu. B. Glazunov1, G. A. Polyakova1, S. A. Korotkov1,2, D. V. Lezhnev1 1Institute of Forest Science of the Russian Academy of Sciences, Uspenskoe village, Russian Federation 2Bauman Moscow State Technical University, Mytishchinskiy Branch, Mytishchi, Russian Federation
The character of restorative forest successions after catastrophic disturbances is largely determined by their initial stage. The natural regeneration of tree and shrub species has been investigated, taking into account the influence of herbaceous vegetation on this process in two clear cut area at the site of the 2017 windfall in near Moscow Region. The type of clear cut area is mixed herbs with predominance of reed grass. The soil-forming rocks are sandy loam and light loam. Accounting for the natural renewal of tree and shrub species and soil vegetation cover was carried out on circular test plots with an area of 10 m2, located at different distances from the edges. 102 species of herbs were found. Clearings differ in the species composition of herbaceous vegetation. The Jaccard similarity index was 37.3 %. This difference is due to the presence of rare species, the most represented species are found in both clear cut area. In clear cut area No. 1, 17 species of trees and shrubs were noted, and in clear cut area No. 2, 13 species. Scots pine ( Pinus sylvestris L.), silver ( Betula pendula Roth) and moor ( Betula pubescens Ehrh.) birch, and aspen ( Populus tremula L.) dominated in both clearings. Successful regeneration of pine trees was noted at a distance of no more than 50 m from the forest wall. Small-leaved species are found throughout in the clear cut area. The amount of natural reforestation of pine significantly exceeds the amount of birch and aspen, at the same time, pine is much inferior to these species in height. Among herbaceous plants, the renewal of pine is most hindered by the reed grass ( Calamagrostis arundinacea (L) Roth.), and among deciduous species - aspen. For the successful formation of pine stands, it is recommended to carry out thinning.
At the beginning of the 21st century in St. Petersburg, the number of species of trees and shrubs that have entered a reproductive state has noticeably increased. A number of them produced seed offspring for the first time over a long period of introduction. In such conditions, when the levels of adaptation change so noticeably and the biological characteristics of different plant species manifest themselves differently, the role and importance of conducting and processing long-term series of continuous phenological observations undoubtedly increases. During the period of continuous phenological monitoring (1980-2022) in the Botanical Garden of Peter the Great Komarov Botanical Institute Russian Academy of Sciences established that against the backdrop of climate warming in St. Petersburg, which began in the late 1980s, biological cyclicity, according to N. E. Bulygin, manifests itself in the alternation of early warm periods (1989, 1990, 1992, 1995, 2007, 2008, 2014, 2015, 2016, 2019, 2020, 2022) and late cold years (1980, 1982, 1985, 1987, 1996, 1998, 2003, 2004, 2006, 2011, 2012, 2013), which is reflected on the reproductive activity of woody plants and their ability to survive winter conditions. For the period 2001-2022 238 species entered the reproductive state, many of which had previously been in a vegetative state for decades. The improvement in the reproductive sphere of plants is especially noticeable after the abnormally warm winter of 2006/07; it intensified in 2015. This year and 2020 became the warmest during the period of instrumental meteorological observations in St. Petersburg. 50.8 % of cases of the first flowering and fruiting occur in early warm years; and only 16.4 % of cases - in late cold years. When summing up the results of introduction and assessing the prospects for breeding woody plants for urban floristics, it is necessary to take into account the cyclical climate of the region, the seasonal rhythm of plant development and their rhythm-adaptive connections.
H. Caliskan1, U. Birben2, S. Ozden2 1Cankiri Karatekin University, Graduate School of Natural and Applied Sciences, Cankiri, Turkiye 2Cankiri Karatekin University, Cankiri, Turkiye
Keywords: Forest law, forest perception, legal systems, national point of view, sustainability
Forest governance around the globe has been making positive progress in the sense of resource management in the last decade. However, differences in legal systems and policies cause some difficulties in advancing towards the common goal of forest sustainability. This study is aimed to contribute resources sustainability by comparing forest laws in different legal systems so, as to get good governance and practice examples. The legal systems discussed have been determined as Romano-Germanic (Civilian), Anglo-Saxon, Islamic, and Socialist law. To represent these legal systems Germany, Canada, Nigeria, the People’s Republic of China, and Türkiye have been selected. Forest laws of those countries examined and discussed for definition of forest, ownership types, and protection. It has been concluded different legal systems has an important effect on forest perception and the spatial area of forests. The sustainability approach in the Chinese Forest Law has more positive effects on the forest when compared to other laws. That kind of perception of forest law may lead better forest governance and could be the best example for the rest of the world.
