冲击荷载作用下喷射混凝土的动态力学性能

发布时间：2018-03-06 18:17

本文选题：喷射混凝土　切入点：速凝剂　出处：《安徽理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：在地下岩石掘进或开挖爆破工程(包括矿山井巷工程、隧道工程、人防工程、大小地下空间硐室工程等),爆破产生的振动效应影响着围岩和支护结构的稳定性。研究喷射混凝层对爆破动态作用的响应以及其本身的动态力学特性,对减少爆破振动的影响、提高喷射混凝土结构的整体性和稳定性以及承载能力都有着重要意义。鉴于目前国内外的研究主要是静力学性能,对其动力学性能的则较少。因此,有必要对喷射混凝土的力学性能进行研究。论文采用分离式霍普金森压杆(SHPB)系统,研究不同速凝剂配比、不同龄期、不同冲击速度时喷射混凝土的动态力学性能。冲击荷载作用下,四种速凝剂配比的喷射混凝土应力应变曲线有区别。一天龄期时,其曲线峰值相当,峰值部分扰动较大;之后,随着龄期的增大,速凝剂添加量与峰值应力成反比,并且峰值部分扰动逐渐减少;7天与14天龄期时曲线呈现出两段弹性变化。喷射混凝土早期低气压预冲击,一天和三天早龄期类似于粘弹性阶段,28天的强度有所升高。2%速凝剂时的喷射混凝土后期强度增长明显。不同龄期预冲击对喷射混凝土波速实测表明,1、3天龄期的预冲击对喷射混凝土的波速影响较大,其波速降低明显;3天龄期之后的预冲击,对混凝土波速影响较小;整体上,预冲击龄期越晚,对混凝土波速的影响就越小。
[Abstract]:Excavation or excavation of underground rocks (including mine shaft engineering, tunnel engineering, civil air defense engineering, etc.). The vibration effect produced by blasting affects the stability of surrounding rock and supporting structure in large and small underground chamber engineering. The response of jetting coagulation layer to blasting dynamic action and its dynamic mechanical properties are studied, and the effect of blasting vibration reduction on blasting vibration is studied. It is of great significance to improve the integrity, stability and bearing capacity of shotcrete structures. It is necessary to study the mechanical properties of shotcrete. Dynamic mechanical properties of shotcrete with different impact velocities. Under impact load, the stress-strain curves of shotcrete with four accelerator ratios are different. At one day of age, the peak value of the curve is equal, and the peak value is partially disturbed. With the increase of age, the addition of accelerator is inversely proportional to the peak stress, and the peak disturbance decreases gradually at 7 and 14 days. The strength of shotcrete in the early stage of one day and three days was increased significantly when the strength was similar to that in the viscoelastic stage of 28 days. The post-strength of shotcrete increased obviously when the accelerator was 2%. The measurement of wave velocities of sprayed concrete with different age pre-impact shows that the pre-strength of shotcrete at 3 days of age increases obviously. The impact has a great influence on the wave velocity of shotcrete. The wave velocity decreases obviously after 3 days of age, which has little effect on the wave velocity of concrete. On the whole, the later the pre-impact period is, the less the influence on the wave velocity of concrete is.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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