单轴加卸载作用下井壁混凝土能量演化机理

针对深部地下工程条件的结构混凝土过早失效，易在高应力集中区产生类似“岩爆”现象的破坏等问题，通过不同种类混凝土单轴加卸载和声发射试验，研究典型种类混凝土的能量耗散和释放过程。结果表明:C70钢纤维混凝土和非蒸养型超高性能混凝土(UHPC)的滞回环更加趋于饱满，耗能能力更强。C70普通混凝土易积聚能量，在达到峰值强度时，储存的能量突然间释放，形成混凝土“岩爆”现象;钢纤维混凝土在加载过程由于塑性变形较大，导致损耗大量能量的同时会造成井壁混凝土的片裂行为;UHPC通过自身均匀的小损伤耗散较多的能量，且破坏之后仍能保持一定的完整性，其延性较好，不会引起能量瞬间涌出的“岩爆”破坏。能量耗散促使混凝土黏聚力劣化，能量释放导致混凝土的最终破坏，UHPC的结构自适应能力很强，可以有效抵御深地高地应力的作用，保护矿井的安全作业。

Energy evolution mechanism of shaft wall concrete under uniaxial loading and unloading compression

In terms of the fundamental problems,such as the premature failure of structural concrete in deep underground engineering conditions and the phenomenon of rock burst in high stress areas,the energy dissi-pation and release process of different kinds of concrete were studied by uniaxial loading and unloading compression and acoustic emission tests.The results show that the hysteretic loop of C70 steel fiber reinforced concrete and UHPC tends to be fuller and the capacity of energy dissipation is stronger.C70 ordinary concrete is easy to accumulate energy,when the peak strength is reached,the stored energy is suddenly released,forming the phenomenon of rock burst of concrete.The plastic deformation of steel fiber reinforced concrete is larger in the loading process,which will lead to the formation of flaky fragments when the energy dissipation of concrete.UHPC will dissipate more energy through its own fine cracks,and still maintain a certain degree of integrity after destruction.The ductility of UHPC is better,so it will not cause the destruction of the instantaneous energy.Energy dissipation leads to the deterioration of concrete cohesion and energy release leads to the ultimate destruction of concrete.The adaptive ability of UHPC structure is very strong,which can effectively resist the role of deep high ground stress to protect mine safety.