Effect of thermal treatment on unloading-induced fracture activation of granites during triaxial shear slip experiments  

作　　者：Richeng Liu Xinjie Zhu Mingyao Wei Wei Qiao Liyuan Yu Minghui Hu 

机构地区：[1]State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou,221116,China [2]CUMT-IoT Perception Mine Research Center,China University of Mining and Technology,Xuzhou,221116,China [3]School of Resources and Geosciences,China University of Mining and Technology,Xuzhou,221116,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2025年第2期931-945,共15页岩石力学与岩土工程学报(英文)

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);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.

摘　　要：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.

关 键 词：Thermal treatment Unloading-induced slip Fracture activation Damage mode 

分 类 号：TU45[建筑科学—岩土工程]