基于声发射技术的冻融劣化混凝土损伤特性研究

Study on Damage Characteristics of Concrete Subjected to Freeze-Thaw Deterioration Based on Acoustic Emission Technology

利用动静力三轴仪进行冻融劣化后的混凝土单轴循环加卸载试验,试验过程中同步采用声发射装置全程采集声发射数据,对声发射能量参数与应力应变的关系进行分析,并进行基于声发射技术的混凝土损伤特性分析。结果表明:整个循环加卸荷过程中,声发射的能量数主要集中出现在加载阶段,卸载阶段的能量数很少或几乎没有;混凝土的损伤变量随着累计塑性应变的增大呈现先缓慢增大、随后迅速增大、最后趋于缓慢增大的变化趋势;通过分析不同冻融循环次数、不同应变速率下的损伤变化规律,将混凝土循环加卸荷的损伤过程分为损伤起始、损伤稳定发展、损伤破坏三个阶段;在相同应变速率下,随着冻融循环次数的增加,混凝土的累计塑性应变整体上呈增大的趋势。

Uniaxial cyclic loading unloading test of concrete after freeze-thaw cracking was carried out by dynamic and static three axis instrument, synchronous data transmitting device using transmit the entire collection sound during the test. The relationship between acoustic emission energy parameters and stress and strain was analyzed and the damage characteristics of concrete based on acoustic emission technology were analyzed. The results show that during the loading and unloading process, the number of AE energy mainly occurs in the loading stage, with little or no energy release in the unloading stage; the damage of concrete variables with the increase of cumulative plastic strain shows the trend of slow increase at first, then rapid increase and finally slow increase; through the analysis of different freeze-thaw cycles, different damage variation of strain rate of concrete, the whole process of cyclic loading and unloading damage is divided into three stages of initial damage stage, damage stable development stage and damage stage; at the same strain rate, with the increase of the number of freeze-thaw cycles, the cumulative plastic strain of concrete is increasing as a whole.