中等应变率条件下分层充填体的动态力学特性及失稳特征（英文）

Dynamic mechanical properties and instability behavior of layered backfill under intermediate strain rates

为了得到应变率为10~80 s(~1)的动载条件下分层充填体的动态力学特性及变形破坏规律,利用分离式Hopkinson杆系统对其进行冲击加载实验。实验结果表明,分层充填体的动态抗压强度及动态强度增长因子与应变率均存在正相关关系。分层充填体的动态抗压强度随着算术平均灰砂比的增加而增大,与静态抗压强度相比,分层充填体的动态峰值强度增加了11%~163%。此外,分层充填体的能量吸收率随着水泥平均含量的升高而降低,且介于组成分层充填体的单体试块之间。分层充填体的形变表现出了不连续性,其强度较低的部分形变程度大于强度较高的部分。为了分析分层充填体试块的稳定性状态,利用基于Stenerding-Lehnigk准则推导出的改进方程来判断分层充填体的失稳条件,计算结果与3组试验结果的误差仅为4.80%、3.89%和4.66%。

To obtain dynamic mechanical properties and failure rule of layered backfill under strain rates from10to80s-1,impactloading test on layered backfill specimens(LBS)was conducted by using split Hopkinson pressure bar system.The results indicatethat positive correlation can be found between dynamic compressive strength and strain rate,as well as between strength increasefactor and strain rate.Dynamic compressive strength of LBS gets higher as the arithmetic average cement-sand ratio increases.Compared with static compressive strength,dynamic compressive strength of LBS is enhanced by11%to163%.In addition,theenergy dissipating rate of LBS lies between that of corresponding single specimens,and it decreases as the average cement contentincreases.Deformation of LBS shows obvious discontinuity,deformation degree of lower strength part of LBS is generally higherthan that of higher strength part.A revised brittle fracture criterion based on the Stenerding-Lehnigk criterion is applied to analyzingthe fracture status of LBS,and the average relevant errors of the3groups between the test results and calculation results are4.80%,3.89%and4.66%,respectively.