摘要
为探究胶结充填体早期损伤对后期力学性能影响机制,将龄期3,7,14,21 d的充填体施加4种不同程度的静载损伤,养护28 d后开展单轴压缩试验、超声波测试、电镜微观结构扫描,从宏–细–微三个尺度探讨充填体早期损伤对后期力学性能影响机制。结果表明:损伤对龄期3和7 d充填体后期抗压强度影响较小,在一定压损条件下充填体后期抗压强度上升,对龄期14和21 d充填体后期抗压强度均产生弱化作用,对各个龄期充填体后期弹性变形能力起到强化作用;基于波速变化建立损伤程度与充填体力学特性之间的定量关系,发现损伤龄期3和7 d充填体存在损伤阈值和修复阈值;随着损伤程度的增大,充填体内部结构由数量较多的细小裂隙逐渐扩大为单一裂隙,裂隙断面处的连接物质主要为水化产物C-S-H网状凝胶;龄期3和7 d充填体内部存在大量未完全水化的水泥颗粒,养护后期产生的凝胶产物足以填充大部分损伤裂隙,故损伤对其后期抗压强度影响较小,而龄期14和21 d充填体未完全水化的水泥颗粒减少,后期产生的凝胶产物不足以填充损伤裂隙,内部结构颗粒之间联系较差,故损伤对其后期抗压强度弱化作用显著。研究结果可为矿山充填体工作提供指导意义。
To investigate the influence mechanism of early load damage on later mechanical properties of the cemented paste backfill,four different degrees of static load damage were applied to the backfill at ages of 3,7,14 and 21 d.After 28 d of maintenance,uniaxial compression tests,ultrasonic tests and electron microscopic microstructure scans were conducted to investigate the influence mechanism of early load damage on later mechanical properties of the backfill under three scales of macro-fine-micro.The results show that:the load damage had less effect on the late compressive strength of the backfill at ages 3 and 7 d,and the late compressive strength of the backfill increased under certain load conditions.The late compressive strength of the backfill at age 14 and 21 d was weakened.The late elastic deformation capacity of the cemented backfill at each age was strengthened.The quantitative relationship between the degree of load and the physical properties of the backfill was established based on the variation of wave velocity.It finds that there was a damage threshold and a repair threshold for the backfill at 3 and 7 d of damage age.With the degree of damage load increased,the internal structure of the backfill gradually expanded from a larger number of fine fissures to a single fissure,and the connecting material at the fissure section was mainly the hydration product C-S-H reticulated gel.At ages 3 and 7 d,there were a large number of incompletely hydrated cement particles inside the backfill,and the gel products produced at the later stage of maintenance were sufficient to fill most of the damaged fissures.Therefore,the damage had a less effect on its later compressive strength.While at ages 14 and 21 d,the incompletely hydrated cement particles in the backfill were reduced,and the gel products produced at the later stage were insufficient to fill the damaged fissures.Thus,the connection between the internal structural particles was poor,and the damage had a significant weakening effect on its later compressive strength.The results of the study can provide guidance for working with mine backfilling.
作者
甘德清
张雅洁
刘志义
孙海宽
GAN Deqing;ZHANG Yajie;LIU Zhiyi;SUN Haikuan(College of Mining Engineering,North China University of Technology,Tangshan,Hebei 063210,China;Hebei Mining Development and Safety Engineering Laboratory,North China University of Technology,Tangshan,Hebei 063210,China)
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2023年第4期821-832,共12页
Chinese Journal of Rock Mechanics and Engineering
基金
河北省自然科学基金资助项目(E2021209127)
国家自然科学基金资助项目(52074124)。
关键词
采矿工程
尾砂胶结充填体
早期损伤
力学特性
超声波测试
SEM扫描
mining engineering
cemented paste backfill
early damage
mechanical properties
ultrasonic testing
SEM scanning
