3种岩石能量演化特征的试验研究

Experimental investigations on energy evolution characteristics of coal,sandstone and granite during loading process

为了探究岩性对受载岩石能量演化特征的影响规律,对煤岩、红砂岩和花岗岩等3种典型岩石试件进行了轴向加卸载试验.结果表明:与煤岩相比,红砂岩和花岗岩峰前不可逆变形较小,峰后应力跌落幅度较大,抗压强度分别是煤岩的4.37倍和5.02倍,弹性模量是煤岩的4.54倍和5.29倍,脆性指数是煤岩的2.32倍和2.81倍.煤岩在接近破坏时弹性能密度显著弱化,而红砂岩和花岗岩此特征不明显;岩石的强度和刚度越大,其储能极限和弹性能增长速率越大;脆性越强,其峰后弹性能释放越快速和彻底.3种岩石的能量分配模式在峰前阶段相似,而峰后阶段岩石脆性越大弹性能比例下降越大,且下降至最小值时所需时间较短,反映了其破坏过程的剧烈性.

Axial loading-unloading tests were conducted on coal, red sandstone and granite sam- ples. Based on these tests, the lithology effect on variation and allocation pattern of elastic en- ergy and dissipated energy were revealed. The results show that compared with coal, the irre- versible deformation of red sandstone and granite before peak point is less, and the stress drops more at the peak point; the compressive strength of red sandstone and granite is 4.37 times and 5.02 times higher than coal respectively, while the elasticity modulus is 4.54 times and 5.29 times, the brittleness index is 2.32 times and 2.81 times. The elastic energy decreases evident- ly when the coal sample approaches failure, but it does not exist for sandstone and granite ; the elastic energy accumulation limit and rate both increase with the increasing strength and stiff- ness, and the elastic energy releases more rapidly and thoroughly after peak point as the rock brittleness rises. Energy allocation patterns of three types of samples are similar before the peak point, but the elastic energy ratio drops more after the peak point when the brittleness is grea- ter, while the falling time is shorter, indicating that the failure is more violent.