基于声发射的自然与饱水状态混凝土动态劈拉特性对比

Comparative Analysis on Dynamic Split Characteristics of Natural and Water Saturated Concretes Based on Acoustic Emission

为研究自然状态与饱水状态混凝土的动态劈拉特性,进行了不同应变速率(10^(-5)/s,10^(-4)/s,10^(-3)/s,10^(-2)/s)下的径向劈拉试验,对混凝土劈拉强度进行了深入分析,并利用实时采集的声发射数据分析自然状态与饱水状态混凝土在劈拉破坏全过程中的能量释放特性及破坏规律。结果表明:自然状态和饱水状态混凝土的劈拉强度随加载速率的增加而增大。在低应变速率(10^(-5)/s,10^(-4)/s和10^(-3)/s)时,由于自由水的楔入作用,饱水状态混凝土的劈拉强度比自然状态混凝土的劈拉强度小;在应变速率为10^(-2)/s时,由于Stefan效应,饱水状态混凝土的劈拉强度比自然状态混凝土大;饱水状态混凝土的动态增强因子比自然状态混凝土的大,饱水状态混凝土率敏感性更显著;声发射信号特征与混凝土的破坏特性相一致,实时采集的声发射信号可对混凝土的劈拉破坏过程进行较准确的监测。

Radial splitting tensile tests for natural and water saturated concrete specimens with size of Φ150 ×150mm was carried out under different strain rates（ 10^（-5）,10^（-4）,10^（-3）and 10^（-2）s^（-1））. Splitting tensile strength of concrete was analyzed in detail,and energy release characteristics and damage law of natural and water saturated concretes were researched in the whole process of splitting tensile damage by real-time acoustic emission data. The results show that： 1） with the increase of loading rate,splitting tensile strength of natural and water saturated concretes increases; 2） at low strain rates（ 10^（-5）,10^（-4）and 10^（-3）/ s）,the splitting tensile strength of water saturated concrete is smaller than that of natural concrete due to the wedging action of free water,whereas at the strain rate of10^（-2）/ s,the splitting tensile strength of water saturated concrete is larger than that of natural concrete due to Stefan effect; 3） dynamic enhancement factor of water saturated concrete is larger than that of natural concrete,and strain rate sensitivity of water saturated concrete is more obvious; 4） acoustic emission signal characteristics is in accordance with concrete failure characteristics,and acoustic emission data can be used to accurately monitor the process of concrete splitting tensile failure.