多应变率动静叠加岩石力学试验系统研制及应用

Development and application of rock mechanics experimental system with multi strain rate dynamic and static superposition

为研究多应变率动静叠加荷载作用下岩石的损伤破坏规律,自主研发了包括装配反力单元、动静叠加单元、蠕变加载单元、智能测控单元的多应变率动静叠加岩石力学试验系统。四大单元分别具有高刚度卯榫拼装、多应变率动静荷载叠加与弹性应变能释放模拟、自动平衡跟随式蠕变加载、多元信息采集融合及突变信息自动高频捕捉等特点,实现了岩石单一表面蠕变荷载(<10-4 s^(-1))+静载(10-4~10-2 s^(-1))、静载+脉冲荷载(10-2~100 s^(-1))、静载+冲击荷载(100~102 s^(-1))、静载+循环冲击荷载等多种类型不同应变率动静荷载叠加。利用该试验系统开展不同应变率动静叠加作用下大理石损伤破坏试验,并利用峰值强度及累积残余应变定量表征了试件损伤演化规律,试验结果表明:蠕变、静载+脉冲、静载+冲击三种加载方式均对岩石产生显著损伤作用,损伤效果由强到弱依次为:静载+脉冲、静载+冲击、蠕变;动静叠加瞬间,试件应变出现突增,当动载明显小于静载时,动载主要产生弹性应变;当动载相同时,试件损伤随静载的增大呈加速增长趋势;当静载相同时,试件损伤随动载应变率的增大呈减小趋势,具有显著应变率效应;静载+循环冲击过程中试件损伤呈现“快速增长→平缓发展→急速上升”的S型演化趋势。

To study the damage law of rock under dynamic and static superimposed loads,a rock mechanics experimental system with multi strain rate dynamic and static superposition was developed.The experimental system includes assembly reaction unit,dynamic and static superposition unit,creep loading unit and intelligent control unit.The four units have the characteristics of assembly with high rigidity,multi strain rate dynamic and static load superposition and simulation of elastic strain energy release,automatic balance creep loading,multi-element information acquisition and automatic high-frequency capture of sudden change information,respectively.Finally,various types of dynamic and static loads with different strain rates,such as creep(<10-4 s^(-1))and static load(10-4–10-2 s^(-1)),static load and pulse load(10-2–100 s^(-1)),static load and impact load(100–102 s^(-1)),static load and cyclic impact load,can be applied on a single rock surface.Using the experimental system,the marble damage and failure experiments under the dynamic and static superposition were carried out,and the damage evolution law quantitatively characterized by the peak strength and cumulative residual strain.The experimental results showed that the creep,static load+pulse,static load+impact have obvious damage effects on rocks,the damage effects from strong to weak are:static load+pulse,static load+impact,creep.At the moment of dynamic and static superposition,the strain increases abruptly,when the dynamic load is significantly smaller than the static load,the dynamic load mainly produces elastic strain.When the dynamic load is the same,the damage increases rapidly with the static load increasing;when the static load is the same,the damage decreases with the increase of the dynamic load strain rate,which has a significant strain rate effect.In the process of static load+cyclic impact,the specimen damage presents an S-shaped evolution trend of“rapid growth→gentle development→rapid rise”.