Currently, numerical simulations of seismic channel waves for the advance detection of geological structures in coal mine roadways focus mainly on modeling two- dimensional wave fields and therefore cannot accurately ...Currently, numerical simulations of seismic channel waves for the advance detection of geological structures in coal mine roadways focus mainly on modeling two- dimensional wave fields and therefore cannot accurately simulate three-dimensional （3-D） full-wave fields or seismic records in a full-space observation system. In this study, we use the first-order velocity-stress staggered-grid finite difference algorithm to simulate 3-D full-wave fields with P-wave sources in front of coal mine roadways. We determine the three components of velocity Vx, Vy, and Vz for the same node in 3-D staggered-grid finite difference models by calculating the average value of Vy, and Vz of the nodes around the same node. We ascertain the wave patterns and their propagation characteristics in both symmetrical and asymmetric coal mine roadway models. Our simulation results indicate that the Rayleigh channel wave is stronger than the Love channel wave in front of the roadway face. The reflected Rayleigh waves from the roadway face are concentrated in the coal seam, release less energy to the roof and floor, and propagate for a longer distance. There are surface waves and refraction head waves around the roadway. In the seismic records, the Rayleigh wave energy is stronger than that of the Love channel wave along coal walls of the roadway, and the interference of the head waves and surface waves with the Rayleigh channel wave is weaker than with the Love channel wave. It is thus difficult to identify the Love channel wave in the seismic records. Increasing the depth of the receivers in the coal walls can effectively weaken the interference of surface waves with the Rayleigh channel wave, but cannot weaken the interference of surface waves with the Love channel wave. Our research results also suggest that the Love channel wave, which is often used to detect geological structures in coal mine stopes, is not suitable for detecting geological structures in front of coal mine roadways. Instead, the Rayleigh channel wave can be used for the advance detection of geological structures in coal mine roadways.展开更多
The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone...The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers.Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face.A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China.展开更多
基金supported by National Natural Science Foundation of China(Nos.41204077,41372290,41572244,51034003,51174210,and 51304126)natural science foundation of Shandong Province(Nos.ZR2011EEZ002 and ZR2013EEQ019)State Key Research Development Program of China(No.2016YFC0600708-3)
文摘Currently, numerical simulations of seismic channel waves for the advance detection of geological structures in coal mine roadways focus mainly on modeling two- dimensional wave fields and therefore cannot accurately simulate three-dimensional （3-D） full-wave fields or seismic records in a full-space observation system. In this study, we use the first-order velocity-stress staggered-grid finite difference algorithm to simulate 3-D full-wave fields with P-wave sources in front of coal mine roadways. We determine the three components of velocity Vx, Vy, and Vz for the same node in 3-D staggered-grid finite difference models by calculating the average value of Vy, and Vz of the nodes around the same node. We ascertain the wave patterns and their propagation characteristics in both symmetrical and asymmetric coal mine roadway models. Our simulation results indicate that the Rayleigh channel wave is stronger than the Love channel wave in front of the roadway face. The reflected Rayleigh waves from the roadway face are concentrated in the coal seam, release less energy to the roof and floor, and propagate for a longer distance. There are surface waves and refraction head waves around the roadway. In the seismic records, the Rayleigh wave energy is stronger than that of the Love channel wave along coal walls of the roadway, and the interference of the head waves and surface waves with the Rayleigh channel wave is weaker than with the Love channel wave. It is thus difficult to identify the Love channel wave in the seismic records. Increasing the depth of the receivers in the coal walls can effectively weaken the interference of surface waves with the Rayleigh channel wave, but cannot weaken the interference of surface waves with the Love channel wave. Our research results also suggest that the Love channel wave, which is often used to detect geological structures in coal mine stopes, is not suitable for detecting geological structures in front of coal mine roadways. Instead, the Rayleigh channel wave can be used for the advance detection of geological structures in coal mine roadways.
基金Projects Y2007F46 supported by the Natural Science Foundation of Shandong Province20070424005 by the Doctor Disciplines Special Scientific Researc Foundation of the Ministry of Education+1 种基金108158 by the Key Project of the Ministry of Education of China50539080 by the National Natural Scienc Foundation of China
文摘The mechanism of mine water inrushes in coal mines in China differs considerably from that in other countries.In China, most water inrushes occur from floor strata, where the water-inrush sources are karstic limestone aquifers.Our study describes the mechanism of mine water inrushes through a fault in the mine floor using principles of strata mechanics and the path of water inrush from an aquifer to the working face.A criterion to judge whether a ground water inrush will occur through a fault or not is also described, together with a case history of water inflow in the Feicheng coalfield, China.
