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为揭示新浇混凝土爆破振动损伤累积机制,设计并开展新浇混凝土爆破振动损伤累积模拟试验。首先测量超声波波速,并计算损伤值;然后利用试验结果和损伤断裂力学原理,分析新浇混凝土振动损伤累积规律与机制。结果表明:受振混凝土超声波速变化经历快速增长、缓慢增长、降低和稳定4个阶段;损伤值在第一阶段快速减小,进入第2阶段后损伤劣化效应显现,损伤值随着振动次数的增加先快速增加、后缓慢增加;受振混凝土中的峰值波速和稳定波速均低于基准混凝土的相应波速,高强混凝土损伤累积劣化效应较普通混凝土明显。新浇混凝土振动损伤累积是原生微裂纹尖端局部损伤变形、微裂纹和细观裂纹扩展的结果。
In order to reveal the accumulation mechanism of blasting vibration damage of newly cast concrete, the cumulative simulation test of vibration damage of newly cast concrete blasting was designed and carried out. Firstly, the ultrasonic wave velocity is measured and the damage value is calculated. Then, the cumulative rule and mechanism of vibration damage of fresh concrete are analyzed based on the experimental results and the mechanics of damage fracture mechanics. The results show that the ultrasonic vibration velocity of concrete undergoing vibration experiences rapid growth, slowly increasing, decreasing and stabilizing four stages; the damage value decreases rapidly in the first stage, the damage and deteriorating effect appears after entering the second stage, the damage value increases with the vibration frequency First increase rapidly and then increase slowly; the peak and steady wave velocities in the vibration-affected concrete are all lower than the corresponding wave velocities of the reference concrete, and the cumulative deterioration of the high-strength concrete is more obvious than that of ordinary concrete. Vibration damage accumulation of fresh concrete is the result of local damage deformation, micro-cracks and mesoscopic crack propagation of the primary microcracks.