含倾角结构面的胶结充填体动态力学特性研究

为探求充填过程中多次充填产生不同倾角充填面对充填体产生的影响,制备含不同倾角结构面的胶结充填体(CTB)试件以及完整试件,并采用分离式霍普金森压杆(SHPB),对CTB试件进行单次与循环冲击破坏试验。试验得出:在单次冲击试验中,完整试件峰值应变和平均应变率小于含结构面倾角的试件,随着试件倾角的增加,试件的动态抗压强度逐渐降低;含结构面倾角试件表现出两种不同的应力-应变曲线特征。循环冲击试验下,结构面倾角越大试件抵抗冲击的能力越弱;含结构面倾角试件在第一次循环冲击下的应力-应变曲线与完整试件特征一致,而当循环次数增加时,应力-应变曲线特征与单次冲击下类似,在达到动态峰值应力前后,出现了显著的低应力波峰现象。随着结构面倾角的增加,充填体基体之间结构的致密性降低,导致结构面上裂纹数量的增多以及裂纹宽度的扩大,在微观结构上验证了结构面倾角的增加会引起结构面处剪应力的增大及充填体破坏模式发生改变,同时充填体容易沿着结构面处发生断裂。

Study of dynamic mechanical properties of colluvial fillers with inclined structural surfaces

In order to investigate the effect of different inclination filling surfaces on the filling body generated by multiple filling processes, the CBT specimens with different inclination structural surfaces and intact specimens were prepared, and the single and cyclic impact damage tests were conducted on the CBT specimens using a split Hopkinson pressure bar (SHPB). The peak strain and average strain rate of the intact specimen were smaller than those of the specimen with structural face inclination in the single impact test, and the dynamic compressive strength of the specimen decreased gradually with the increase of the specimen inclination; the specimen with structural face inclination showed two different stress-strain curve characteristics. Under the cyclic impact test, the larger the inclination angle of the structural surface, the weaker the ability of the specimen to resist the impact; the stress-strain curve of the specimen with the inclination angle of the structural surface was consistent with the characteristics of the intact specimen under the first cyclic impact, while when the number of cycles increased, the characteristics of the stress-strain curve were similar to those under a single impact, and a significant low stress crest phenomenon appeared before and after reaching the dynamic peak stress. With the increase of the dip angle of the structural surface, the denseness of the structure between the matrix of the filler decreases, which leads to the increase of the number of cracks on the structural surface and the expansion of the crack width, which verifies microstructurally that the increase of the dip angle of the structural surface causes the increase of the shear stress at the structural surface and the change of the damage mode of the filler, and the filler is prone to fracture along the structural surface.