冻融循环后湿筛混凝土强度试验与破坏准则研究

Study of strength experiment and failure criterion of wet-screened concrete after freeze-thaw cycles

采用快速冻融法,对湿筛混凝土试件进行了冻融循环。利用大型动三轴试验机,对冻融循环后的湿筛混凝土试件进行单轴压和4种应力比的双轴压试验,观察试件的破坏形态和表面裂缝分布情况,测得双轴主压方向的极限强度,剖析了冻融循环次数和应力比对极限强度的影响规律。试验结果表明:随冻融循环次数的增加,湿筛混凝土的双轴压极限强度呈非线性降低;在冻融循环次数相同的情况下,双轴压极限强度相对于其单轴强度均有所提高,而提高幅度取决于应力比。提出了带有冻融循环次数和应力比参数的修正湿筛混凝土破坏准则公式,可为寒冷地区的海洋工程、水工结构强度分析和寿命预测提供理论依据。

The experimental study of the strength of wet-screened aggregate concrete was carried out using the rapid freeze-thaw method.Then the concrete specimen was tested using the static and dynamic tri-axial experimental machine under 4 biaxial compression stress ratios and uniaxial expression.The failure modes of these concrete specimens and the cracks distribution on the surfaces were observed and the ultimate strength in the main biaxial compression direction was obtained as well.The influence of freeze-thaw cycles and the stress ratios on the ultimate compressive strength were given as well.The results showed that the biaxial ultimate compressive strength of the concrete decreases non-linearly with the increase of freeze-thaw cycles;under the same cycles,the biaxial ultimate compressive strength increased compared with the uniaxial strength,and the increasing amplitude was determined by stress ratios.On the basis,the modified failure criterion with consideration of the freeze-thaw cycles and stress ratio was proposed.