三轴压缩下不同岩性煤岩体的强度及变形特征

Different lithologies coal and rock under the triaxial compression strength and deformation characteristics

煤矿井下存在多种岩性的煤岩体,其力学强度和变形特征直接影响巷道支护效果。利用CRIMS-DDL600电子万能试验机,进行了不同围压下砂岩、矸石与煤样的三轴压缩试验,采用莫尔准则诠释了不同岩性的试样破坏角大小不等,通过图形对比和现象分析,得到了围压对3种不同岩性的试样应力、应变曲线及变性特征的影响。结果表明:3种性质的试样三轴压缩过程中都经历了初始压密阶段、弹性阶段、屈服阶段与破坏阶段,且围压越大,试样初始压密阶段越长;在试验加载的围压范围内,3种性质的试样破坏形式并不相同,且3种不同岩性的试样破坏角大小相差较大,砂岩破坏角最大,煤破坏角最小,3种性质的试样其峰值强度随着围压的增大而增长;3种性质的试样符合Coulomb强度准则,依据莫尔应力圆给出3种试样内聚力和内摩擦角的大小;随着围压的增大,3种性质的试样弹性模量呈增大趋势,且围压对试样弹性模量的影响因试样类型的不同而不同。

There are many lithology of coal and rock in coal mines,its mechanical strength and deforma- tion characteristics directly affect the roadway supporting effect. With CRIMS-DDL600 electronic universal testing machine,the sandstone,coal gangue and triaxial compression tests are carried out under different confining pressures. By means of the criterion of Moore explains different lithology of specimens damage Angle sizes, and by comparing the graphics and analysis of the phenomenon, the effect of confining pres- sure on the three samples stress-strain curve and deformation features is analyzed and compared. The re- suits show that：Specimens with three kinds of properties of the three axial compression process has gone through the initial compaction stage, elastic stage, yield and failure stage, and the more pressure and confi- ning,the longer specimen initial compression phase is;in confining pressure range, three kinds of failure forms of samples are not the same,and specimen failure angle＇ s size of the three kinds of rock are of large difference,meanwhile there peak strength increases with the increase of confining pressure; also there properties are consistent with Coulomb strength criterion ,and the size of cohesion and internal friction an- gle is given according to Moore＇ s circle;with the growing of confining pressure,elastic modulus of three kinds increases ,and the pressure effect on the elastic modulus varies due to the sample types.