The thermal effect has a significant impact on the activation and slip characteristics of fractures.In this study,four pairs of granite fractures were treated by temperatures T ranging from 25℃to 900℃.The fractures ...The thermal effect has a significant impact on the activation and slip characteristics of fractures.In this study,four pairs of granite fractures were treated by temperatures T ranging from 25℃to 900℃.The fractures were then employed to carry out triaxial unloading-induced shear slip experiments.The step unloading of confining pressure σ_(3) was used as a disturbed stress to activate fractures that were in a near-critical stress state.The slip characteristics,frictional behaviors,as well as damage modes of fractures with different T,were systematically investigated.The results show that at T=25℃ and 300℃,no stick-slip events were observed,and the slipping process of the fractures was characterized by aseismic slip and creep,respectively.For T=600℃ and 900℃,the fractures slipped stably,with occasional interruptions by episodic stick-slip events.Ultimately,they entered the dynamic slip stage after a series of consecutive stick-slip episodes.With increasing T,the number of sheared-off asperities increases due to thermal damage,which in turn leads to an increase in the occurrence of stick-slip events.The slip modes of the fractures transited from friction strengthening to friction weakening.As T increased from 300℃to 900℃,a considerable quantity of generated gouge layer acted as a lubricant for the slipping of fractures.This resulted in a notable increase in the proportion of aseismic slip,which rose from 24%to 54%.As the temperature increased from 25℃to 900℃,the crack length increased exponentially from 2.975 mm to 45.349 mm.For T=600℃ and 900℃,the duration between stick-slip events decreased as stick-slip events occurred more frequently.展开更多
基金funded by the National Key Research and Development Program of China,(Grant No.2022YFE0128300)the Natural Science Foundation of China(Grant No.52379113)+1 种基金the Fundamental Research Funds for the Central Universities of China(Grant No.2024-10945)the Postgraduate Research&Practice Innovation Program of Jiangsu Province of China.
文摘The thermal effect has a significant impact on the activation and slip characteristics of fractures.In this study,four pairs of granite fractures were treated by temperatures T ranging from 25℃to 900℃.The fractures were then employed to carry out triaxial unloading-induced shear slip experiments.The step unloading of confining pressure σ_(3) was used as a disturbed stress to activate fractures that were in a near-critical stress state.The slip characteristics,frictional behaviors,as well as damage modes of fractures with different T,were systematically investigated.The results show that at T=25℃ and 300℃,no stick-slip events were observed,and the slipping process of the fractures was characterized by aseismic slip and creep,respectively.For T=600℃ and 900℃,the fractures slipped stably,with occasional interruptions by episodic stick-slip events.Ultimately,they entered the dynamic slip stage after a series of consecutive stick-slip episodes.With increasing T,the number of sheared-off asperities increases due to thermal damage,which in turn leads to an increase in the occurrence of stick-slip events.The slip modes of the fractures transited from friction strengthening to friction weakening.As T increased from 300℃to 900℃,a considerable quantity of generated gouge layer acted as a lubricant for the slipping of fractures.This resulted in a notable increase in the proportion of aseismic slip,which rose from 24%to 54%.As the temperature increased from 25℃to 900℃,the crack length increased exponentially from 2.975 mm to 45.349 mm.For T=600℃ and 900℃,the duration between stick-slip events decreased as stick-slip events occurred more frequently.
