Molecular statics was employed to simulate interaction between screw dislocation and twin boundaries（TB） in hexagonal close-packed zirconium. In the moving TB model, the interaction of a moving {10ˉ12} TB with a st...Molecular statics was employed to simulate interaction between screw dislocation and twin boundaries（TB） in hexagonal close-packed zirconium. In the moving TB model, the interaction of a moving {10ˉ12} TB with a static 1/311ˉ20{10ˉ10} screw dislocation was investigated. Twinning dislocation（TD） nucleation and movement play an important role in the interaction. The screw dislocation passes through the moving TB and changes to a basal one with a wide core. In the moving dislocation model, a moving 1/31120{1010} dislocation passes through the TB, converting into a basal one containing two partial dislocations and an extremely short stacking fault. If the TB changes to the {1011} one, the moving1/31120{1010} prismatic screw dislocation can be absorbed by the static TB and dissociated into two TDs on the TB. Along with the stress-strain relationship, results reveal the complicated mechanisms of interactions between the dislocation and TBs.展开更多
The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pi...The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pingzhuang Western Surface Mine and based on strength reduction method, the dynamic instability processes of the top high and steep slope was simulated. Also, the landslide mode was determined, the characteristics of the displacement distribution, the deformation, failure, and the stress distribution in the slope were demonstrated, and the stability was calculated. Conclusions can be drawn as follows： the landslide or failure of high and steep slopes on a surface mine is a gradual process, in which the slope undergoes the generation, expansion, and connection of the fractures and the displacement increases until landslide occurs; a small portion of the upper rocks fail due to the tension and the lower rocks fail due to the shear; the potential sliding surface is combined and the essential cause of the landslide is the shear stress concentration.展开更多
On 25 April 2015,an M_w 7.8 earthquake occurred on the Main Himalaya Thrust fault with a dip angle of^7° about77 km northwest of Kathmandu,Nepal.This Nepal Gorkha event is the largest one on the Himalayan thrust ...On 25 April 2015,an M_w 7.8 earthquake occurred on the Main Himalaya Thrust fault with a dip angle of^7° about77 km northwest of Kathmandu,Nepal.This Nepal Gorkha event is the largest one on the Himalayan thrust belt since 1950.Here we use the compressive sensing method in the frequency domain to track the seismic radiation and rupture process of this event using teleseismic P waves recorded by array stations in North America.We also compute the distribution of static shear stress changes on the fault plane from a coseismic slip model.Our results indicate a dominant east-southeastward unilateral rupture process from the epicenter with an average rupture speed of ~3 km s^(-1).Coseismic radiation of this earthquake shows clear frequency-dependent features.The lower frequency(0.05-0.3 Hz) radiation mainly originates from large coseismic slip regions with negative coseismic shear stress changes.In comparison,higher frequency(0.3-0.6 Hz) radiation appears to be from the down-dip part around the margin of large slip areas,which has been loaded and presents positive coseismic shear stress changes.We propose an asperity model to interpret this Nepal earthquake sequence and compare the frequency-dependent coseismic radiation with that in subduction zones.Such frequency-dependent radiation indicates the depth-varying frictional properties on the plate interface of the Nepal section in the main Himalaya thrust system,similar to previous findings in oceanic subduction zones.Our findings provide further evidence of the spatial correlation between changes of static stress status on the fault plane and the observed frequency-dependent coseismic radiation during large earthquakes.Our results show that the frequency-dependent coseismic radiation is not only found for megathrust earthquakes in the oceanic subduction environment,but also holds true for thrust events in the continental collision zone.展开更多
基金Projects(11372032,11602015)supported by the National Natural Science Foundation of China
文摘Molecular statics was employed to simulate interaction between screw dislocation and twin boundaries（TB） in hexagonal close-packed zirconium. In the moving TB model, the interaction of a moving {10ˉ12} TB with a static 1/311ˉ20{10ˉ10} screw dislocation was investigated. Twinning dislocation（TD） nucleation and movement play an important role in the interaction. The screw dislocation passes through the moving TB and changes to a basal one with a wide core. In the moving dislocation model, a moving 1/31120{1010} dislocation passes through the TB, converting into a basal one containing two partial dislocations and an extremely short stacking fault. If the TB changes to the {1011} one, the moving1/31120{1010} prismatic screw dislocation can be absorbed by the static TB and dissociated into two TDs on the TB. Along with the stress-strain relationship, results reveal the complicated mechanisms of interactions between the dislocation and TBs.
基金Supported by the National Natural Science Foundation of China （50375026） the Project of Liaoning Province Department of Education （20060387） Liaoning Province, Guideline Plan Project on Safety in Production and Development of Technology （[2009] No. 88）
文摘The instability and failure mechanism of high and steep slopes in surface mines, and the basis for some reasonable landslide prevention measures were provided using the RFPA-SRM. Based on the actual progress of the Pingzhuang Western Surface Mine and based on strength reduction method, the dynamic instability processes of the top high and steep slope was simulated. Also, the landslide mode was determined, the characteristics of the displacement distribution, the deformation, failure, and the stress distribution in the slope were demonstrated, and the stability was calculated. Conclusions can be drawn as follows： the landslide or failure of high and steep slopes on a surface mine is a gradual process, in which the slope undergoes the generation, expansion, and connection of the fractures and the displacement increases until landslide occurs; a small portion of the upper rocks fail due to the tension and the lower rocks fail due to the shear; the potential sliding surface is combined and the essential cause of the landslide is the shear stress concentration.
基金supported by National Natural Science Foundation of China(Grant Nos.41374055,41225010)Chinese University of Hong Kong Direct Grant for Research(Grant No. 3132771)+1 种基金HKSAR Research Grant Council ECS(Grant No.2191093) and GRF(Grant No.2130509)the Fundamental Research Funds for the Central Universities(Grant No.WK2080000053)
文摘On 25 April 2015,an M_w 7.8 earthquake occurred on the Main Himalaya Thrust fault with a dip angle of^7° about77 km northwest of Kathmandu,Nepal.This Nepal Gorkha event is the largest one on the Himalayan thrust belt since 1950.Here we use the compressive sensing method in the frequency domain to track the seismic radiation and rupture process of this event using teleseismic P waves recorded by array stations in North America.We also compute the distribution of static shear stress changes on the fault plane from a coseismic slip model.Our results indicate a dominant east-southeastward unilateral rupture process from the epicenter with an average rupture speed of ~3 km s^(-1).Coseismic radiation of this earthquake shows clear frequency-dependent features.The lower frequency(0.05-0.3 Hz) radiation mainly originates from large coseismic slip regions with negative coseismic shear stress changes.In comparison,higher frequency(0.3-0.6 Hz) radiation appears to be from the down-dip part around the margin of large slip areas,which has been loaded and presents positive coseismic shear stress changes.We propose an asperity model to interpret this Nepal earthquake sequence and compare the frequency-dependent coseismic radiation with that in subduction zones.Such frequency-dependent radiation indicates the depth-varying frictional properties on the plate interface of the Nepal section in the main Himalaya thrust system,similar to previous findings in oceanic subduction zones.Our findings provide further evidence of the spatial correlation between changes of static stress status on the fault plane and the observed frequency-dependent coseismic radiation during large earthquakes.Our results show that the frequency-dependent coseismic radiation is not only found for megathrust earthquakes in the oceanic subduction environment,but also holds true for thrust events in the continental collision zone.
