摘要
不同尺度煤体冲击倾向性研究对于厘清煤炭地下开采过程中冲击地压尺寸效应形成机制起着关键作用。为探明煤体冲击倾向性尺寸效应,对不同尺寸煤试件进行单轴压缩及变上限循环加卸载试验。试验结果表明:与标准(ϕ50 mm×100 mm)煤试件相比,小尺寸(ϕ25 mm×50 mm)煤试件的平均单轴抗压强度增加了8.02%,弹性模量增加了23.16%;大尺寸(ϕ75 mm×150 mm)煤试件的平均单轴抗压强度降低了11.03%,弹性模量降低了7.37%。随着煤试件尺寸的增加,声发射累积事件总数不断降低,临近破坏时煤试件表面位移场趋于无序变化。经CT扫描煤体试件内部微裂隙分形维数随其尺寸扩大不断增加,表明较大尺寸煤试件内部裂纹数量增多且空间分布更加复杂,这直接导致煤体呈现出尺寸效应特征。煤体试件尺寸从ϕ25 mm×50 mm增加至ϕ75 mm×150 mm,其剩余弹性能指数C^(EF)由26.53 kJ/m^(3)降低为21.36 kJ/m^(3),这表明尺寸效应将直接影响煤体的冲击倾向性,同种煤体的尺寸越大,其冲击倾向性越小。
The study of coal burst liability at different scales plays a key role in clarifying the formation mechanism of multi-scale effect of rock burst in the process of underground coal mining.The study of coal burst liability at different scales plays a key role in clarifying the formation mechanism of multi-scale effect of rock burst in the process of underground coal mining.In order to explore the multi-scale effect of coal bursting liability,uniaxial compression and cyclic loading and unloading tests with variable upper limit were carried out on coal specimens of different sizes.The results show that compared with the standard(ϕ50 mm×100 mm)coal specimen,the average uniaxial compressive strength of the small size(ϕ25 mm×50 mm)coal specimen is increased by 8.02%,and the elastic modulus is increased by 23.16%.The average uniaxial compressive strength and elastic modulus of large size(ϕ75 mm×150 mm)coal specimens decreased by 11.03%and 7.37%,respectively.With the increase of the size of coal specimens,the total number of AE cumulative events decreases continuously,and the surface displacement field of coal specimens tends to change disordered near failure.According to CT scan,the fractal dimension of microcracks in coal specimen increases with the expansion of its size,indicating that the number of cracks in coal specimen with larger size increases and the spatial distribution is more complex,which directly leads to the multi-scale effect of coal.When the size of coal specimen increases fromϕ25 mm×50 mm toϕ75 mm×150 mm,its residual elastic energy index C^(EF) decreases from 26.53 kJ/m^(3) to 21.36 kJ/m^(3),which indicates that the multi-scale effect directly affects the bursting liability of coal.The larger the size of the same coal,the smaller the bursting liability.
作者
孙如达
张传玖
李红平
贾兵兵
SUN Ruda;ZHANG Chuanjiu;LI Hongping;JIA Bingbing(CCTEG Coal Mining Research Institute Co.,Ltd.,Beijing 100013,China;Buertai Coal Mine,CHN Energy Shendong Coal Group Co.,Ltd,Ordos 017209,China;CHN Enerngy Group Xinjiang Energy Co.,Ltd.,Urumqi 830000,China)
出处
《煤炭科学技术》
CAS
CSCD
北大核心
2022年第S02期170-179,共10页
Coal Science and Technology
关键词
冲击倾向性
尺寸效应
煤体
裂纹
剩余弹性能指数
impact tendency
multi-scale effect
coal
crack
index of residual elastic energy
