Based on the application of practical engineering,propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The ...Based on the application of practical engineering,propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that,under blast loading,there are three zones in the rock: a crushed zone nearby the explosive charge,a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.展开更多
In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpres...In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented.展开更多
Plane charge explosion technique (PCET) is one of the major techniques frequently used in large-scale blast-resistant structure tests. An FEM model was established, which can simulate the process of air releasing from...Plane charge explosion technique (PCET) is one of the major techniques frequently used in large-scale blast-resistant structure tests. An FEM model was established, which can simulate the process of air releasing from the blast cavity. The effects of the charge density, the interval of the charge strip, the distance of the charges from the structure, and the mass of backfill soil on the overpressures applied on the tested structures were analyzed by the FEM model. The quantitative relationships between the peak value and the duration of the overpressure and the above-mentioned affecting parameters were established. Agreement between numerical results and the test data was obtained.展开更多
Earthquake, explosion, and a nuclear test data are compared with forward modeling and band-pass filtered surface wave amplitude data for exploring methodologies to improve earthquake–explosion discrimination. The pro...Earthquake, explosion, and a nuclear test data are compared with forward modeling and band-pass filtered surface wave amplitude data for exploring methodologies to improve earthquake–explosion discrimination. The proposed discrimination method is based on the solutions of a double integral transformation in the wavenumber and frequency domains. Recorded explosion data on June 26, 2001（39.212°N, 125.383°E） and October 30, 2001（38.748°N, 125.267°E）, a nuclear test on October 9, 2006（41.275°N, 129.095°E）, and two earthquakes on April 14, 2002（39.207°N, 125.686°E） and June 7, 2002（38.703°N, 125.638°E）, all in North Korea, are used to discriminate between explosions and earthquakes by seismic wave analysis and numerical modeling. The explosion signal is characterized by first P waves with higher energy than that of S waves. Rg waves are clearly dominant at 0.05–0.5 Hz in the explosion data but not in the earthquake data. This feature is attributed to the dominant P waves in the explosion and their coupling with the SH components.展开更多
In recent years,with the development of simulations about supernova explosion,we have a better understanding about the density profiles and the shock waves in supernovae than before.There might be a reverse shock wave...In recent years,with the development of simulations about supernova explosion,we have a better understanding about the density profiles and the shock waves in supernovae than before.There might be a reverse shock wave,another sudden change of density except the forward shock wave,or even no shock wave,emerging in the supernova.Instead of using the expression of the crossing probability at the high resonance,PH,we have studied the matter effects on neutrino oscillations in different supernova models.In detail,we have calculated the survival probability of νe(P_s)and the conversion probability of ν_x(P_c) in the Schrodinger equation within a simplified two-flavor framework for a certain case,in which the neutrino transfers through the supernova matter from an initial flavor eigenstate located at the core of the supernova.Our calculations was based on the data of density in three different supernova models obtained from simulations.In our work,we do not steepen the density gradient around the border of the shock wave,which differs to what was done in most of the other simulations.It is found that the mass and the density distribution of the supernova do make a difference on the behavior of P_s and P_c.With the results of P_s and P_c,we can estimate the number of νe(and ν_x) remained in the beam after they go through the matter in the supernova.展开更多
基金Projects 2002CB412705 supported by the National Basic Research & Development Program (973)50579042 by the National Natural Science Foundation of China+1 种基金NCET-05-0215 by the Chinese New-Century Outstanding FellowshipJD102900553 by the Key Laboratories of Beijing Municipal Commis- sion of Education and Science and Technology Commission
文摘Based on the application of practical engineering,propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that,under blast loading,there are three zones in the rock: a crushed zone nearby the explosive charge,a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.
文摘In the analysis of a structure subjected to an explosion event, the determination of the blast load constitutes a crucial step. The effect of the blast load on the structure depends not only on the peak shock overpressure, but also the impulse (hence the duration). For structures with a regular geometry, the blast load may be fairly well estimated using appropriate empirical formulae; however, for more complex situations, a direct simulation using appropriate computational techniques is necessary. This paper presents a numerical simulation study on the prediction of the blast load in free air using a hydrocode, with focus on the sensitivity of the simulated blast load to the mesh grid size. The simulation results are compared with empirical predictions. It is found that the simulated blast load is sensitive to the mesh size, especially in the close-in range, and with a practically affordable mesh grid density, the blast load tends to be systematically underestimated. The study is extended to internal blast cases. An example concrete slab under internal explosion is analyzed using a coupled analysis scheme. The internal blast load from the simulation is examined and the response of the RC slab is commented.
文摘Plane charge explosion technique (PCET) is one of the major techniques frequently used in large-scale blast-resistant structure tests. An FEM model was established, which can simulate the process of air releasing from the blast cavity. The effects of the charge density, the interval of the charge strip, the distance of the charges from the structure, and the mass of backfill soil on the overpressures applied on the tested structures were analyzed by the FEM model. The quantitative relationships between the peak value and the duration of the overpressure and the above-mentioned affecting parameters were established. Agreement between numerical results and the test data was obtained.
文摘Earthquake, explosion, and a nuclear test data are compared with forward modeling and band-pass filtered surface wave amplitude data for exploring methodologies to improve earthquake–explosion discrimination. The proposed discrimination method is based on the solutions of a double integral transformation in the wavenumber and frequency domains. Recorded explosion data on June 26, 2001（39.212°N, 125.383°E） and October 30, 2001（38.748°N, 125.267°E）, a nuclear test on October 9, 2006（41.275°N, 129.095°E）, and two earthquakes on April 14, 2002（39.207°N, 125.686°E） and June 7, 2002（38.703°N, 125.638°E）, all in North Korea, are used to discriminate between explosions and earthquakes by seismic wave analysis and numerical modeling. The explosion signal is characterized by first P waves with higher energy than that of S waves. Rg waves are clearly dominant at 0.05–0.5 Hz in the explosion data but not in the earthquake data. This feature is attributed to the dominant P waves in the explosion and their coupling with the SH components.
基金Supported by National Science Foundation of China under Grant Nos.11175020 and 11275025
文摘In recent years,with the development of simulations about supernova explosion,we have a better understanding about the density profiles and the shock waves in supernovae than before.There might be a reverse shock wave,another sudden change of density except the forward shock wave,or even no shock wave,emerging in the supernova.Instead of using the expression of the crossing probability at the high resonance,PH,we have studied the matter effects on neutrino oscillations in different supernova models.In detail,we have calculated the survival probability of νe(P_s)and the conversion probability of ν_x(P_c) in the Schrodinger equation within a simplified two-flavor framework for a certain case,in which the neutrino transfers through the supernova matter from an initial flavor eigenstate located at the core of the supernova.Our calculations was based on the data of density in three different supernova models obtained from simulations.In our work,we do not steepen the density gradient around the border of the shock wave,which differs to what was done in most of the other simulations.It is found that the mass and the density distribution of the supernova do make a difference on the behavior of P_s and P_c.With the results of P_s and P_c,we can estimate the number of νe(and ν_x) remained in the beam after they go through the matter in the supernova.
