力-热耦合作用下煤岩动力学特性和破碎机理研究  

Study on Dynamic Characteristics and Fracture Mechanism of Coal Rock under Action of Mechanical-thermal Coupling

作　　者：李鹏龙 罗宁[1,2,3] 索云琛 柴亚博 孙锐 LI Peng-long;LUO Ning;SUO Yun-chen;CHAI Ya-bo;SUN Rui(State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and Technology,Xuzhou 221116,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China;State Key Laboratory of Explosion Science and Technology,Beijing Institute of Technology,Beijing 100081,China)

机构地区：[1]中国矿业大学深部岩土力学与地下工程国家重点实验室,徐州221116 [2]中国矿业大学力学与土木工程学院,徐州221116 [3]北京理工大学爆炸科学与技术国家重点实验室,北京100081

出　　处：《爆破》2024年第4期8-17,60,共11页Blasting

基　　金：国家重点研发计划项目(2020YFA0711800);国家自然基金项目(12072363)。

摘　　要：为了安全高效地进军深部煤炭资源开采,开展深地“三高一扰动”环境下煤岩的动态力学特性和破碎机理研究,采用自主改进的∅50 mm高温同步分离式霍普金森压杆(SHPB)试验系统,对25~200℃温度下煤岩进行动态冲击试验研究,并改进ZWT粘弹性本构模型建立考虑温度效应的煤岩动态本构方程,基于有限差分-离散元数值模拟研究高温效应对煤岩裂纹发育规律及其动态强度的影响。研究表明:高温冲击作用下煤岩的动态应力应变曲线可划分为四个阶段:压密阶段、弹性阶段、裂纹增长阶段和软化失效阶段;随着温度的增加,煤岩的动态抗压强度和动态弹性模量劣化明显,失效应变呈现增加趋势,吸收能则呈现W型波动趋势;破碎粒径减小,分形维数则呈现明显的线性增加,抗压强度越低,破碎程度越高,破碎模式更为复杂;基于ZWT改进后的动态本构模型良好地表达高温冲击后的应力应变关系,但对压密阶段的表达不甚理想;模拟和试验结果显示煤岩在150℃高温后水成分和吸附气体活跃析出,煤基质受热膨胀破裂,出现明显细观裂纹,并逐渐发育为贯通裂纹,其中以剪切裂纹为主。煤岩在100℃下动态压缩的裂纹发育从受撞击面发育贯通,高温劣化煤岩强度。研究结论为“三高一扰动”深部复杂地况下煤炭资源安全高效开采提供基础理论支持。To carry out deep coal mining safely and efficiently,the dynamic mechanical characteristics and fracture mechanism of coal rock in deep earth were investigated under the‘three high and one disturbance’environment.A dynamic impact test of coal rock was carried out using the self-improved∅50 mm high temperature synchronous split Hopkinson pressure bar(SHPB)test equipment at temperatures between 25~200℃.A ZWT viscoelastic constitutive model was also improved to establish a dynamic constitutive equation considering the temperature effect.The influence of high temperature on crack development law and the dynamic strength of coal rock was investigated based on the coupling of the finite difference and discrete element methods.The results show four stages to the dynamic stress-strain curve of coal rock under high-temperature impact:compaction,elastic,crack propagation,and softening failure.The dynamic compressive strength and dynamic elastic modulus of coal rock significantly decrease as temperature increases.In contrast,the failure strain increases,and the absorbed energy varies in a W-shaped pattern.The fractal dimension increases linearly as the particle size decreases.The degree and complexity of the fragmentation mechanism increase as the compressive strength decreases.Although the improved dynamic constitutive model based on ZWT could adequately express the stress-strain relationship following a high-temperature impact,it does not apply to the compaction stage.According to the simulation and test results,water and adsorbed gas actively escape in the coal rock at 150℃.The coal matrix is also heated and expanded,which induces cracks.There are apparent mesoscopic cracks initially and gradually developed through cracks,mainly shear ones.The crack development of coal rock under dynamic compression at 100℃develops through the impact surface,and the high temperature deteriorates the strength of coal rock.

关 键 词：深部煤岩 力-热耦合 分离式霍普金森压杆 动态本构模型 有限差分-离散元 

分 类 号：TD235.3[矿业工程—矿井建设]