摘要
中低应变率扰动荷载诱发的张拉破坏失稳是引起深部煤炭资源和遗留煤炭资源开采动力灾害事故发生的主要原因之一,分析动力扰动作用下煤岩的拉伸力学响应特征对灾害的预测与防治具有重要意义。对此,开展中低应变率扰动荷载作用下的砂岩巴西劈裂试验,分析不同预静载水平和扰动荷载幅值对砂岩动态拉伸力学响应特征的影响。结果表明:扰动荷载导致的损伤程度与预静载水平正相关,预静载由7 kN增大为20 kN,AE能量水平增大约11倍,宏观上表现为抗拉强度的降低,预静载为11和16 kN的扰动损伤砂岩的抗拉强度分别为12.4和11.5MPa,分别降低5.6%和12.7%;验证扰动荷载应力门槛值的存在,高应力状态砂岩在小幅动力扰动荷载作用过程中并不会发生破坏,拉应变呈对数型缓增;高应力状态砂岩在越过应力门槛值的扰动荷载作用过程中发生破坏,破坏前扰动荷载作用周期数随着扰动荷载幅值增加指数型递减;预静载和动载幅值的增加均促进岩样中心主张拉裂纹附近次级张拉裂纹扩展。岩样动态拉伸破坏前的应变突增前兆可以为动力灾害预警提供参考。
The tensile failure and instability induced by medium and low strain rate disturbance load is one of the main causes of dynamic disasters in deep coal resources and residual coal resources mining.And it is of great significance to analyze the tensile mechanical response characteristics of coal and rock under dynamic disturbance for disaster prediction and prevention.In this regard,Brazilian splitting test of sandstone under medium low strain rate disturbance load was carried out.To analyze the influence of different pre-static load levels and disturbance load amplitude on dynamic tensile mechanical response characteristics of sandstone.The results show that:The degree of damage due to disturbed loading was positively correlated with the pre-static load level,and the AE energy level increased by about 11 times when the pre-static load increased from 7 kN to 20 kN.Macroscopically,this is manifested as a reduction in tensile strength.The tensile strength of disturbed sandstone with pre-static load of 11kN and 16 kN is 12.4 MPa and 11.5 MPa,respectively,which is 5.6%and 12.7%lower than that of static tensile strength.The existence of stress threshold value of disturbance load is verified.The sandstone in high stress state will not be destroyed in the process of small amplitude dynamic disturbance load,and the tensile strain increases logarithmically.The sandstones in high stress state are destroyed during the application of disturbing loads greater than the stress threshold.And the number of cycles of perturbation loading before damage decreases exponentially with increasing amplitude.The increase of pre-static load level and dynamic load amplitude both promotes the expansion of secondary tension cracks in the vicinity of the central tensile crack in the rock sample.The precursor of strain surge before dynamic tensile failure of rock specimen can provide reference for dynamic disaster warning.
作者
文晓泽
冯国瑞
郭军
王朋飞
钱瑞鹏
朱林俊
郝晨良
樊一江
WEN Xiaoze;FENG Gourui;GUO Jun;WANG Pengfei;QIAN Ruipeng;ZHU Linjun;HAO Chenliang;FAN Yijiang(College of Mining Technology,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Research Center of Green Mining Engineering Technology in Shanxi Province,Taiyuan University of Technology,Taiyuan,Shanxi 030024,China;Postdoctoral Research Station of Shanxi Coking Coal Group Co.,Ltd.,Taiyuan,Shanxi 030024,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2022年第S01期2812-2822,共11页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金青年基金项目(51904203)
国家杰出青年科学基金项目(51925402)
山西省科技重大专项项目(20201102004)
关键词
岩石力学
动静载耦合作用
动态响应
巴西劈裂
砂岩
破坏形态
rock mechanics
dynamic and static load coupling action
dynamic response
Brazilian splitting test
sandstone
destruction properties
