冻融环境下混凝土损伤劣化机制的力学试验研究

通过对自然状态以及饱水状态下的混凝土试样分别进行冻融循环试验,并在不同冻融循环次数后对混凝土试样进行单轴压缩强度测定,研究了材料弹性模量、抗压强度、应力应变关系等力学特性的变化规律,以此分析了在冻融环境下混凝土材料的损伤劣化机制。结果表明:混凝土冻融损伤劣化模式具有多样性,随着冻融循环次数的增加,混凝土试样逐渐呈现出颗粒脱落、微裂纹萌生扩展、剥蚀和块落等多种形式相结合的损伤劣化模式;而试样弹性模量及强度明显减小,且强度受水影响非常显著。该研究从试验角度解释了在冻融环境下混凝土力学性能的变化规律,为寒区重大工程冻融灾变预测、防治提供了较可靠的试验与理论依据。

Experimental Study of Damage Degradation Mechanism of Concrete in Freeze-Thaw Environment

Freeze-thaw cycling experiment was conducted for concrete in natural state and saturated state, respectively, and uniaxial compression strength experiment for concrete sample was carried out after different freeze-thaw cycle times. Mechanical characteristics of material such as elastic modulus, compression strength, stress-strain curve were analyzed. So, the damage degradation mechanism of concrete in freeze-thaw environment was systematically studied. Results show that the damage degradation model of concrete due to freeze-thaw cycling presents diversity, with the increase of freeze-thaw cycling times, particles gradually shed from sample surface, micro-cracks appear and propagate, combining denudation and block falling. Meanwhile, the more the times of freeze-thaw cycling are, the more reduction of the elastic modulus and strength of specimen, so the water influence on strength is very significant. This study explains the mechanical property change of concrete in freeze-thaw environment mainly from experimental point of view. It provides experimental and theoretical basis for freeze-thaw catastrophe prediction and prevention of major engineering project in cold region.