冲击载荷下早龄期充填体力学与损伤特性研究

Study on mechanical and damage characteristics of backfill at early age under impact loads

为了探索损伤龄期对早龄期充填体力学性能的影响,采用分离式Hopkinson压杆(SHPB)试验装置,研究充填体在经3、5、7、9 d龄期养护后不同冲击载荷作用下的力学与损伤特性。结果表明龄期为3、5 d的充填体强度较低,峰值应变大,在达到峰值应变后仍处于较高的应力状态,表现出一定的延性,具有较强的塑性和黏弹性;龄期7、9 d的充填体峰值应变变小,到达峰值应变后应力水平迅速降低,表现出脆性材料的特性;早龄期充填体损伤度随着应变的增加而增加,损伤曲线主要表现为上凸型曲线,随着龄期的增长,上凸越显著。因此,鉴于早龄期充填体对损伤龄期的敏感性,在实际生产过程中,应充分考虑充填体早期养护龄期的保障。

In order to explore the dynamic characteristics of backfill at early age,the Separate Hopkinson Pressure Bar(SHPB)test device was used to study the mechanical properties and damage characteristics of the backfill under different impact loads after 3,5,7,and 9 days’curing.The results show that the backfill with curing periods of 3 and 5 days has low strength and large peak strain,and after reaching the peak strain,it is still in a higher stress state,showing a certain ductility,and strong plasticity and viscoelasticity.The peak strain of the filling materials with curing periods of 7 and 9 days decreases,and the stress level decreases rapidly after reaching the peak strain,showing the characteristics of brittle materials.The damage degree of backfill at early age increases with the rising of strain,and the damage curve is mainly convex curve.With the increase of curing period,the convex curve becomes more obvious.Therefore,in view of the sensitivity of backfill at early age to damage,the guarantee of curing period of backfill at early age should be fully considered in the actual production process.