Rock brittleness is an important index evaluating geotechnical stability and failure mode, and it is also influenced by pore fluid pressure, especially in deep underground mining. To evaluate the brittleness from stress–strain curves of uniaxial compression, uniaxial compressive tests were carried out on water-pressurized coal samples, and a new energetic brittleness index was proposed. The saturated coal samples were classified into brittle, transitional, and ductile groups according to the stress–strain behavior of uniaxial compression. It is found that the pore water enhanced brittle coal strength, but reduced strength of transitional and ductile coal. Compared to ductile and transitional coal samples, the brittle coal is of a lower elastic modulus, but showing a higher capability of elastic energy storage prior to peak stress. For brittle coal, significant acoustic emission (AE) events occurred at the peak stress, but for ductile and transitional coal substantial acoustic emission occurred in the post-peak-stress stage suggesting significant elastic energy storage and insignificant energy dissipation feature prior to peak stress. Assuming that the total energy consists of the accumulated elastic energy prior to the crack coalescence point, and the dissipated energy after the crack coalescence point, a new brittleness index was proposed based on strain energy integration from stress–strain curves of uniaxial compression. The new brittleness index shows great superiority in avoiding the subjective mechanical parameter determination and can be conveniently calculated from uniaxial compression tests.

岩石脆性是评价岩土工程稳定性和破坏模式的重要指标，并且还受到孔隙流体压力的影响，特别是在深部地下采矿中。为了从单轴压缩的应力-应变曲线评估脆性，对水压煤样品进行了单轴压缩试验，并提出了一种新的高能脆性指数。根据单轴压缩的应力-应变行为，将饱和煤样品分为脆性，过渡性和韧性组。发现孔隙水增强了脆性煤的强度，但降低了过渡煤和延性煤的强度。与延性和过渡煤样品相比，脆性煤具有较低的弹性模量，但在出现峰值应力之前表现出较高的弹性能量存储能力。对于脆性煤，在峰值应力处会发生显着的声发射（AE）事件，但对于延性和过渡煤，在峰值后应力阶段会发生大量的声发射，这表明在峰值应力之前显着的弹性能量存储和微不足道的能量消散特征。假设总能量由裂纹合并点之前的累积弹性能和裂纹合并点之后的耗散能量组成，则基于单轴压缩应力-应变曲线的应变能积分，提出了一种新的脆性指数。新的脆性指数在避免主观力学参数确定方面显示出极大的优势，并且可以通过单轴压缩试验方便地进行计算。但是对于延性和过渡煤，在峰值后应力阶段会发生大量的声发射，这表明在峰值应力之前显着的弹性能量存储和不明显的能量耗散特征。假设总能量由裂纹合并点之前的累积弹性能和裂纹合并点之后的耗散能量组成，则基于单轴压缩应力-应变曲线的应变能积分，提出了一种新的脆性指数。新的脆性指数在避免主观力学参数确定方面显示出极大的优势，并且可以通过单轴压缩试验方便地进行计算。但是对于延性和过渡煤，在峰值后应力阶段会发生大量的声发射，这表明在峰值应力之前显着的弹性能量存储和不明显的能量耗散特征。假设总能量由裂纹合并点之前的累积弹性能和裂纹合并点之后的耗散能量组成，则基于单轴压缩应力-应变曲线的应变能积分，提出了一种新的脆性指数。新的脆性指数在避免主观力学参数确定方面显示出极大的优势，并且可以通过单轴压缩试验方便地进行计算。