In this paper,we determined an earthquake sequence location in the Xingfengjiang area from June,2007 to July,2014 and the 3 D P-wave velocity structure by a simultaneous inversion method. On that basis,we studied the ...In this paper,we determined an earthquake sequence location in the Xingfengjiang area from June,2007 to July,2014 and the 3 D P-wave velocity structure by a simultaneous inversion method. On that basis,we studied the occurrence features of active tectonics and the earthquake source mechanism. The results show that the reservoir fracture system has a tendency to increase with gradual depth from southeast to northwest,consistent with gravitational field research results. There are 4 high velocity zones( HVZ) under the depth of the 7 km-12 km crust between the Xinfengjiang Reservoir dam and Xichang District,Dongyuan. The max velocity of the biggest HVZ which is under Xichang is 6. 3 km/s. Under the reservoir dam there is a strong tectonic deformation zone,as the center exit Renzishi fault( F_2),Nanshan-Aotou faults( F_4),Heyuan fault( F_1) and Shijiao-Xingang-Baitian fault( F_5),7 earthquakes with M_L≥ 5. 0( including M 6. 1 in March,1962) occurred at the high gradient zone of the HVZ Ⅲ and HVZ Ⅳ edge which has been under the reservoir dam since 1960, with relativity energy releasing more thoroughly. Moderate seismic activity occurred at the HVZ Ⅰ edge which has been under Xichang since 2012,and is a danger zone for M5. 0 earthquakes in the future.展开更多
We perform Rayleigh wave tomography in east Guangdong and its surrounding regions by applying the ambient noise method to broadband data recorded at 26 stations from Guangdong,Fujian and Jiangxi Digital Seismic Networ...We perform Rayleigh wave tomography in east Guangdong and its surrounding regions by applying the ambient noise method to broadband data recorded at 26 stations from Guangdong,Fujian and Jiangxi Digital Seismic Networks.Cross-correlations of verticalcomponent ambient noise data are computed in one-day segments and stacked over seven months from March to September,2011.Then Rayleigh wave group dispersion curves are measured using the frequency-time analysis method.Group velocity maps at periods from5s to 15s are inverted.The resulting group velocity maps generally show good correlation with tectonic features,reflecting the velocity variations in the shallow crust.The basin areas are clearly resolved with lower group velocities at the short periods due to thick sedimentary layers,and the mountain areas with higher group velocities due to thin sedimentary layers.The variations of group velocity on the map can draw out the distribution of basins and mountains in study areas.The geothermal field can change the group velocity obviously,and lower group velocities are always found in high geothermal areas.The velocity maps indicate that a low-velocity layer may be found in the study areas.展开更多
The stability of the centrifugal pump has not been well revealed because of the complexity of internal flow. To analyze the flow characteristics of a centrifugal pump operating at low capacity, methods of numerical si...The stability of the centrifugal pump has not been well revealed because of the complexity of internal flow. To analyze the flow characteristics of a centrifugal pump operating at low capacity, methods of numerical simulation and experimental research were adopted in this paper. Characteristics of the inner flow were obtained. Standard k-s turbulence models were used to calculate the inner flow of the pump under off-design conditions. The distri- bution of the energy gradient function K was obtained by three-dimensional numerical simulation at different flow rates. The relative velocity component was acquired from the absolute velocity obtained in particle image velocimetry. By comparing with experimental results, it was found that flow instability occurs at the position of maximum K. The flow stability reduces with an increasing flow rate. The research results provide a theoretical basis for the optimization design of a centrifugal pump.展开更多
Studying the effect of geometrically irregular bodies on the mechanical behavior of fault activity is of significance in understanding the seismic activity along a fault zone. By using rock mechanics ex- periment with...Studying the effect of geometrically irregular bodies on the mechanical behavior of fault activity is of significance in understanding the seismic activity along a fault zone. By using rock mechanics ex- periment with medium-scale samples, we have studied the effect of fault jogs, the most common irregularity along fault zones, on frictional behavior. The research indicates that extensional fault jog can be easily fractured because of its low strength and the fractured jog has no obvious resistance to fault sliding, and the micro-fractures occurring in the jog are indicative of stick-slip along the faults. The fault zone containing extensional jogs is characterized by velocity weakening and can be described by rate and state friction law. Compressional fault jog makes fault sliding more difficult because of its high fracturing strength, but the micro-fractures occurring in the tensile areas around fault ends at higher stress level can provide necessary condition for occurrence of stick-slip along the faults before the jog is fractured and thus act as precursors of fault instability. Compression jog can be taken as a stable indicator of fault segmentation until the jog is completely fractured and two faults are linked.展开更多
基金sponsored by the National Natural Science Foundation of China(41676057)the Scientific Program of Guangdong Province(2012A030200005)
文摘In this paper,we determined an earthquake sequence location in the Xingfengjiang area from June,2007 to July,2014 and the 3 D P-wave velocity structure by a simultaneous inversion method. On that basis,we studied the occurrence features of active tectonics and the earthquake source mechanism. The results show that the reservoir fracture system has a tendency to increase with gradual depth from southeast to northwest,consistent with gravitational field research results. There are 4 high velocity zones( HVZ) under the depth of the 7 km-12 km crust between the Xinfengjiang Reservoir dam and Xichang District,Dongyuan. The max velocity of the biggest HVZ which is under Xichang is 6. 3 km/s. Under the reservoir dam there is a strong tectonic deformation zone,as the center exit Renzishi fault( F_2),Nanshan-Aotou faults( F_4),Heyuan fault( F_1) and Shijiao-Xingang-Baitian fault( F_5),7 earthquakes with M_L≥ 5. 0( including M 6. 1 in March,1962) occurred at the high gradient zone of the HVZ Ⅲ and HVZ Ⅳ edge which has been under the reservoir dam since 1960, with relativity energy releasing more thoroughly. Moderate seismic activity occurred at the HVZ Ⅰ edge which has been under Xichang since 2012,and is a danger zone for M5. 0 earthquakes in the future.
基金funded by the 2011 Earthquake Tracking Project of CEA(Grant No.2011020105)the open fund project of State Key Laboratory of Earthquake Dynamics(Grant No.LED2011B04)
文摘We perform Rayleigh wave tomography in east Guangdong and its surrounding regions by applying the ambient noise method to broadband data recorded at 26 stations from Guangdong,Fujian and Jiangxi Digital Seismic Networks.Cross-correlations of verticalcomponent ambient noise data are computed in one-day segments and stacked over seven months from March to September,2011.Then Rayleigh wave group dispersion curves are measured using the frequency-time analysis method.Group velocity maps at periods from5s to 15s are inverted.The resulting group velocity maps generally show good correlation with tectonic features,reflecting the velocity variations in the shallow crust.The basin areas are clearly resolved with lower group velocities at the short periods due to thick sedimentary layers,and the mountain areas with higher group velocities due to thin sedimentary layers.The variations of group velocity on the map can draw out the distribution of basins and mountains in study areas.The geothermal field can change the group velocity obviously,and lower group velocities are always found in high geothermal areas.The velocity maps indicate that a low-velocity layer may be found in the study areas.
基金supported by Key Projects in the National Science & Technology Pillar Program (No. 2013 BAF05B01)Public Projects of Zhejiang Province (No. 2014C31116)+1 种基金521 Talent Project of Zhejiang Sci-Tech University, Fluid Engineering Innovation Team of Zhejiang Sci-Tech University (No. 11132932611309)National Natural Science Foundation of China (No. 51409233)
文摘The stability of the centrifugal pump has not been well revealed because of the complexity of internal flow. To analyze the flow characteristics of a centrifugal pump operating at low capacity, methods of numerical simulation and experimental research were adopted in this paper. Characteristics of the inner flow were obtained. Standard k-s turbulence models were used to calculate the inner flow of the pump under off-design conditions. The distri- bution of the energy gradient function K was obtained by three-dimensional numerical simulation at different flow rates. The relative velocity component was acquired from the absolute velocity obtained in particle image velocimetry. By comparing with experimental results, it was found that flow instability occurs at the position of maximum K. The flow stability reduces with an increasing flow rate. The research results provide a theoretical basis for the optimization design of a centrifugal pump.
基金the National Basic Research Program of China (Grant No. 2004CB418405)National Key Technologies R&D Program (Grant No. 2006BAC01B03)
文摘Studying the effect of geometrically irregular bodies on the mechanical behavior of fault activity is of significance in understanding the seismic activity along a fault zone. By using rock mechanics ex- periment with medium-scale samples, we have studied the effect of fault jogs, the most common irregularity along fault zones, on frictional behavior. The research indicates that extensional fault jog can be easily fractured because of its low strength and the fractured jog has no obvious resistance to fault sliding, and the micro-fractures occurring in the jog are indicative of stick-slip along the faults. The fault zone containing extensional jogs is characterized by velocity weakening and can be described by rate and state friction law. Compressional fault jog makes fault sliding more difficult because of its high fracturing strength, but the micro-fractures occurring in the tensile areas around fault ends at higher stress level can provide necessary condition for occurrence of stick-slip along the faults before the jog is fractured and thus act as precursors of fault instability. Compression jog can be taken as a stable indicator of fault segmentation until the jog is completely fractured and two faults are linked.
