摘要
煤岩复合承载结构所处的应力边界条件不同,冲击地压在巷道中的显现特征和前兆规律亦不相同。采用高频振动采集及孔内成像三轴动静载试验系统,开展了高静载和动静载耦合作用下煤岩组合体真三轴单面临空试验,分析了煤岩组合体界面处力学特征和强度条件,探究了不同应力边界下煤岩组合体的破坏形态、动力显现特征和声发射信号的演变规律。研究结果表明:(1)受煤岩变形相互制约的影响,交界面处砂岩强度被“弱化”。当界面处煤体裂隙尖端的应力大于“弱化”后砂岩强度时,裂隙将穿过煤岩界面发育至砂岩中,砂岩呈现出屈曲层裂、劈裂成板的破坏形态。(2)高静载作用下,煤岩组合体变形破坏特征和声发射信号具有明显的前兆规律,组合体发生承载失效前煤体局部颗粒弹射动能增大、弹射颗粒块度降低,声发射信号由“高频低能”向“高频高能”转变,组合体的破坏形态以剪切-张拉复合破坏为主。(3)受冲击动载影响,顶底板砂岩夹持作用减弱,煤体裂纹尖端应力得不到有效积聚,裂纹扩展到煤岩交界面时被阻隔,组合体以煤样的张拉破坏为主,声发射信号呈现出“高频高能”的特点,但大多集中在冲击破坏之后,导致组合体动力破坏难以预测。(4)与纯静载作用相比,虽然动静载耦合作用下静载水平较低,但煤岩组合体的抛射质量和抛射碎块的分形维数较大、平均破碎块度较小,说明动载对煤岩组合体的破坏起到了正向激励的作用,静载为煤岩体动力破坏提供了应力和能量条件。
The characteristics and precursory law of rock burst in roadway are different when the coal-rock composite bearing structure is under different stress boundary conditions.The true triaxial loading and single face unloading test is performed on coal-rock combination bodies under high static and dynamic load,using high frequency vibration acquisition and borehole imaging triaxial static and dynamic load experimental system.The mechanical characteristics and strength conditions at the interface of coal and rock mass are analyzed.Failure modes,dynamic characteristics and evolution of acoustic emission signals of coal-rock combination bodies under different stress boundaries are investigated.The results show that:(1)the strength of sandstone at the interface is"weakened"due to the mutual restriction of coal and rock deformation.When the stress at the crack tip of the coal body at the interface is greater than the strength of the"weakened"sandstone,the crack will develop into the sandstone through the coal rock interface,and the sandstone presents the failure form of buckling spalling and splitting into plates.(2)Under high static loading,the deformation and failure characteristics of coal-rock combination bodies and the acoustic emission signal have obvious precursory law.Before the bearing failure of coal-rock combination bodies,the local particle ejection kinetic energy of coal body increases,the particle lumpiness decreases,and the acoustic emission signal changes from"high frequency and low energy"to"high frequency and high energy".The failure mode of coal-rock mass is mainly shear-tension composite failure.(3)Under the impact dynamic loading,the loading effect of sandstone on the top and bottom plates is weakened,the stress at the crack tip of the coal body can not be effectively accumulated,and the crack is blocked when it extends to the coal rock interface.The combination is dominated by the tensile failure of coal samples,and the acoustic emission signal shows the characteristics of"high frequency and high ene
作者
杨科
刘文杰
马衍坤
许日杰
池小楼
ANG Ke;LIU Wen-jie;MA Yan-kun;XU Ri-jie;CHI Xiao-lou(State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan,Anhui 232001,China;Institute of Energy,Hefei Comprehensive National Science Center,Hefei,Anhui,230031,China;National&Local Joint Engineering Research Center of Precision Coal Mining,Anhui University of Science and Technology,Huainan,Anhui 232001,China;Key Laboratory of Mining Coal Safety and Efficiently Constructed by Anhui Province and Ministry of Education,Anhui University of Science and Technology,Huainan,Anhui 232001,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2022年第1期15-27,共13页
Rock and Soil Mechanics
基金
国家自然科学基金联合基金重点项目(No.U21A20110)
安徽省“115”产业创新团队资助项目。
关键词
采矿工程
冲击地压
动静耦合加载
煤岩组合体
动力显现特征
前兆信息规律
mining engineering
rock burst
dynamic and static coupled loading
coal-rock combined samples
dynamic characteristics
premonitory information law
