摘要
利用MTS815对煤岩展开单轴和8、16、25 MPa三轴压缩试验,探讨不同围压下煤岩的强度及变形特征。研究结果表明:煤岩应力-应变曲线经历线弹性、屈服、破坏3个阶段,延性特征随围压升高愈发明显;随着围压的升高,煤岩峰值应变增大,弹性模量呈二次函数增长趋势;煤岩在单轴压缩下多发生脆性破坏,随着围压升高,煤岩出现明显的主导破坏面,并且破碎体中大体积煤块所占比重增大;平均块度、分形维数与围压存在一定的相关性;不同围压下,煤岩强度变形特征满足Coulomb强度准则,残余强度及达到峰值应力的时间与围压呈线性关系,峰值强度对围压的敏感性高于残余强度,残余内摩擦角及粘聚力均小于峰值强度对应的值,在引入强度衰减系数后,发现其变化特征与煤岩变形破坏过程表现的性质吻合,煤岩对围压的敏感性较强。
Uniaxial and 8,16,25 MPa triaxial compression tests were carried out on coal-rock using MTS815 to investigate the strength and deformation characteristics of coal-rock under different confining pressures.The results show that the stress-strain curve of coal-rock undergoes three stages of linear elasticity,yield and failure,and the ductility characteristics become more obvious with the increase of confining pressure.With the increase of confining pressure,the peak strain of coal-rock increases,and the elastic modulus increases quadratically.Brittle failure of coal-rock often occurs under uniaxial compression,and with the increase of confining pressure,the dominant failure surface of coal-rock appears obviously.Moreover,the proportion of large coal blocks in the fractured body increases.The average block size and fractal dimension have certain correlation with confining pressure.Under different confining pressures,the strength and deformation characteristics of coal-rock meet Coulomb strength criterion,and the residual strength and the time to reach peak stress are linear with confining pressure.The sensitivity of peak strength to confining pressure is higher than that of residual strength,and the residual internal friction angle and cohesion are less than those corresponding to peak strength.By introducing the strength attenuation coefficient,it is found that the characteristics are consistent with the characteristics of the deformation and failure process of coal-rock,and the sensitivity of coal-rock to confining pressure is strong.
作者
刘晓辉
余洁
康家辉
郝齐钧
Liu Xiaohui;Yu Jie;Kang Jiahui;Hao Qijun(Key Laboratory of Fluid and Power Machinery,Ministry of Education,Xihua University,Chengdu610039,P.R.China;State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing100084,P.R.China;State KeyLaboratory of Hydraulics and Mountain River Engineering,Sichuan University,Chengdu610065,P.R.China)
出处
《地下空间与工程学报》
CSCD
北大核心
2019年第5期1341-1352,共12页
Chinese Journal of Underground Space and Engineering
基金
西华大学重点科研基金(Z17113)
水沙科学与水利水电工程国家重点实验室开放研究基金(sklhse-2018-D-03)
四川省教育厅重点科研基金(18ZA0457)
关键词
围压
煤岩
应力-应变曲线
强度
变形
分形
confining pressure
coal-rock
stress-strain curve
strength
deformation
fractal
