高应力下含瓦斯原煤三轴压缩力学特性研究

 利用改制后的煤岩吸附–渗透–力学耦合试验系统，以淮南矿区－780 m标高B10煤层的原煤样作为研究对象，进行高应力下含瓦斯原煤常规三轴压缩力学特性的研究。结果表明：(1) 含瓦斯原煤偏应力–轴向应变曲线主要有弹性、屈服、破坏或峰后软化段构成。其中，弹性段连续、光滑性较差，多呈现出应变“软化–硬化”的波动起伏特点。(2) 峰后脆性破坏特征明显，且在相同初始瓦斯压力下，随着初始有效围压的升高，脆性向延性转化的趋势较弱；而在相同初始有效围压下，初始瓦斯压力越大，脆性破坏特征则越显著。(3) 偏应力–侧向应变曲线与轴向相比，峰前连续、光滑性更好，且几乎均呈线弹性；而峰后变化则趋同。(4) 偏应力–体应变曲线，在低有效围压下表现出扩容机制，且始于峰前；而在高有效围压下，则从峰前越至峰后，始终向右延展，呈现出体积不断收缩的趋势，且瓦斯压力越大，收缩特性越显著。(5) 在相同有效围压下，随着瓦斯压力的增加，峰前轴向、侧向应变增加的速率，以及峰值强度、泊松比均呈增大趋势；而弹性模量则呈降低趋势。(6) 相同瓦斯压力下，随着有效围压的增加，峰前轴向、侧向应变增加的速率，以及泊松比均呈降低趋势；而峰值强度、弹性模量则呈增大趋势。(7) 随着围压或瓦斯压力分别升高，峰值强度均呈线性增大趋势，煤样破坏模式以剪切破坏为主，且强度参数黏聚力和内摩擦角分别为14.02 MPa，25.93°。

Mechanical properties of ram coal containing gas under high triaxal stress compression

The mechanical properties of raw coal specimens containing gas from the B10 seam of －780 m elevation in Huainan coal mine were studied under the conventional high stress triaxial compression by using the modified adsorption-penetration-mechanical coupling test system. The deviatoric stress-axial strain curves of the raw coal containing gas have the stages of elastic deformation，yielding，post-peak brittle failure or strain softening. The elastic period shows the fluctuation associated with strain-softening and strain-hardening. The post peak brittle failure feature is apparent. Under the same initial gas pressure，with the increase of the initial effective confining pressure，the trend of transition between the brittle and ductile is weak. Increasing the initial gas pressure can result in more significant brittle failure if the initial effective confining pressure is kept constant. The deviatoric stress-lateral strain curve has the linear elastic stage which is very smooth. The deviatoric stress-volume strain curve of raw coal containing gas shows dilation under the low effective confining pressure in the pre-peak region. With the increase of the effective confining pressure，the volume dilation delayed. The peak strength increases linearly with increase in confining pressure or gas pressure. The common failure mode for the coal specimens is shear failure and the cohesion and friction angle are 14.02 MPa and 25.93º，respectively.