Earthquakes result from continuous geodynamic processes.A topic of significant interest for the scientific community is to elaborate on the phenomena governing the faulting and fracturing of crustal rocks.Therefore,in...Earthquakes result from continuous geodynamic processes.A topic of significant interest for the scientific community is to elaborate on the phenomena governing the faulting and fracturing of crustal rocks.Therefore,in this study,uniaxial compressive shear failure experiments were conducted on Fangshan marble rock samples with a prefabricated slot to simulate thrust faulting.The center of each marble plate(105 mm × 80 mm × 5 mm) was engraved with a 30-mm long double-sided nonpenetrating slot(depth:2 mm,width:0.5 mm).The deformation and destruction processes of the rock surface were recorded using a high-speed camera.The digital image correlation method was used to calculate the displacement and strain distribution and variation at different loading stages.The accumulative and incremental displacement fields u and v,strain field exand e_(y),and shear strain e_(xy) were analyzed.When the loading level reached its ultimate value,the strain field was concentrated around the prefabricated slot.The concentration reached a maximum at the ends of the prefabricated slot.The magnitude of shear strain reached 0.1.This experiment contributes to our understanding of the dynamic process of active faulting.展开更多
Seismic hazard analysis is gaining increased attention in the present era because of the catastrophic effects of earthquakes.Scientists always have as a goal to develop new techniques that will help forecast earthquak...Seismic hazard analysis is gaining increased attention in the present era because of the catastrophic effects of earthquakes.Scientists always have as a goal to develop new techniques that will help forecast earthquakes before their reoccurrence. In this research,we have performed a shear failure experiment on rock samples with prefabricated cracks to simulate the process of plate movement that forms strike-slip faults. We studied the evolution law of the deformation field to simulate the shear failure experiment, and these results gave us a comprehensive understanding of the elaborate strain distribution law and its formation process with which to identify actual fault zones. We performed uniaxial compression tests on marble slabs with prefabricated double shear cracks to study the distribution and evolution of the deformation field during shear failure. Analysis of the strain field at different loading stages showed that with an increase in the load, the shear strain field initially changed to a disordered-style distribution. Further, the strain field was partially concentrated and finally completely concentrated near the crack and then distributed in the shape of a strip along the crack. We also computed coefficients of variation(CVs) for the physical quantities u, v, and exy, which varied with the load. The CV curves were found to correspond to the different loading stages. We found that at the uniform deformation stage, the CV value was small and changed slowly,whereas at the later nonuniform deformation stage, the CV value increased sharply and changed abruptly. Therefore, the precursor to a rock sample breakdown can be predicted by observing the variation characteristics of CV statistics. The correlation we found between our experimental and theoretical results revealed that our crack evolution and sample deformation results showed good coupling with seismic distribution characteristics near the San Andreas Fault.展开更多
基金This research was supported by the National Key R&D Program of China(Nos.2018YFC1504203 and SQ2017YFSF040025).
文摘Earthquakes result from continuous geodynamic processes.A topic of significant interest for the scientific community is to elaborate on the phenomena governing the faulting and fracturing of crustal rocks.Therefore,in this study,uniaxial compressive shear failure experiments were conducted on Fangshan marble rock samples with a prefabricated slot to simulate thrust faulting.The center of each marble plate(105 mm × 80 mm × 5 mm) was engraved with a 30-mm long double-sided nonpenetrating slot(depth:2 mm,width:0.5 mm).The deformation and destruction processes of the rock surface were recorded using a high-speed camera.The digital image correlation method was used to calculate the displacement and strain distribution and variation at different loading stages.The accumulative and incremental displacement fields u and v,strain field exand e_(y),and shear strain e_(xy) were analyzed.When the loading level reached its ultimate value,the strain field was concentrated around the prefabricated slot.The concentration reached a maximum at the ends of the prefabricated slot.The magnitude of shear strain reached 0.1.This experiment contributes to our understanding of the dynamic process of active faulting.
基金Support for this research was provided by the National Key R&D Program of China(grant numbers 2018YFC1504203 and SQ2017YFSF040025)
文摘Seismic hazard analysis is gaining increased attention in the present era because of the catastrophic effects of earthquakes.Scientists always have as a goal to develop new techniques that will help forecast earthquakes before their reoccurrence. In this research,we have performed a shear failure experiment on rock samples with prefabricated cracks to simulate the process of plate movement that forms strike-slip faults. We studied the evolution law of the deformation field to simulate the shear failure experiment, and these results gave us a comprehensive understanding of the elaborate strain distribution law and its formation process with which to identify actual fault zones. We performed uniaxial compression tests on marble slabs with prefabricated double shear cracks to study the distribution and evolution of the deformation field during shear failure. Analysis of the strain field at different loading stages showed that with an increase in the load, the shear strain field initially changed to a disordered-style distribution. Further, the strain field was partially concentrated and finally completely concentrated near the crack and then distributed in the shape of a strip along the crack. We also computed coefficients of variation(CVs) for the physical quantities u, v, and exy, which varied with the load. The CV curves were found to correspond to the different loading stages. We found that at the uniform deformation stage, the CV value was small and changed slowly,whereas at the later nonuniform deformation stage, the CV value increased sharply and changed abruptly. Therefore, the precursor to a rock sample breakdown can be predicted by observing the variation characteristics of CV statistics. The correlation we found between our experimental and theoretical results revealed that our crack evolution and sample deformation results showed good coupling with seismic distribution characteristics near the San Andreas Fault.
