大骨料混凝土冻融循环后单轴动态抗拉性能试验研究

Experimental Study of Uniaxial Dynamic Tensile Properties of Large Aggregate Concrete after Freezing-Thawing Cycles

针对寒冷地区水工混凝土结构受冻融循环和动荷载作用后会影响其混凝土力学性能,采用混凝土自动快速冻融机进行大骨料混凝土抗冻性试验,再利用大型电液伺服静动三轴试验设备对其进行单轴动态抗拉试验。基于试验数据分析了不同冻融循环次数下的大骨料混凝土的破坏形态和质量损失率及单轴抗拉强度、峰值应力点的应变随冻融次数和应变速率的变化规律。结果表明,动态极限强度较静态极限强度提高的百分比随冻融循环次数增加呈降低趋势,冻融循环作用后单轴抗拉强度在应变速率为1×10-3/s或1×10-2/s时损失最多;在对试验结果分析的基础上建立了冻融循环和动态加载速率作用的大骨料混凝土单轴动态抗拉破坏准则。

In view of the mechanical properties of hydraulic concrete structures affected by freezing-thawing cycles and dynamic loads in cold area,firstly,the frost resistance tests of large aggregate concrete were carried out by using automatic fast freezing-thawing machine and then the uniaxial dynamic tensile tests were carried out by using large electro-hydraulic servo static and dynamic triaxial test equipment.Based on the experimental data,the failure pattern,mass loss rate and the uniaxial tensile strength of large aggregate concrete after different freezing-thawing cycles were analyzed.At the same time,the strain of peak stress varying with the freezing-thawing cycles was discussed,too.The results showed that the percentage of the increase of dynamic ultimate strength compared with static ultimate strength decreased with the increase of freezing-thawing cycles.The uniaxial tensile strength was lost the most under the strain rates 1×10-3/s or 1×10-2/s after freezing-thawing cycles.The uniaxial dynamic tensile failure criterion of large aggregate concrete under the action of freezing-thawing cycles and dynamic loading rate was established based on the analysis of experimental results.