受冻融混凝土动态抗压特性试验研究

通过对受冻融混凝土试件进行单轴动态抗压试验,分析了冻融次数(0、25、50和75次)及应变速率(10-5 s-1、10-4 s-1和10-3 s-1)对混凝土抗压强度、峰值应变和应力-应变曲线的影响.结果表明:不同应变速率下受冻融混凝土的破坏特点有所差异,随着应变率的提高,试件断面更加平整,有较多粗骨料发生破坏;相同冻融次数下,随着应变率的增大,抗压强度明显增加,而峰值应变减小,应力-应变全曲线的峰值点呈前移和上升的趋势,曲线上升段斜率逐渐增大且长度也随之增大,下降段越为陡峭,表现明显的脆性特点;相同应变率下,随着冻融次数的增加,抗压强度均有所降低,而峰值应变逐渐增大,应力-应变全曲线的峰值点表现为明显下降和后移的趋势,其曲线下包面积减小,吸收能量的能力变差;通过对试验结果分析,建立了考虑应变率影响的受冻混凝土受压应力-应变曲线方程.

Experimental Study on Dynamic Compressive Behaviors of Frozen-Thawed Concrete

The uniaxial dynamic compression experiments are conducted on frozen-thawed concrete specimens, the effects of freeze-thaw cycles(0, 25, 50 and 75 times) and strain rates(10 -5 s-1、10 -4 s-1 and 10 -3 s-1 ) on the compressive strength , peak strain and stress-strain curve are systematically analyzed .The test results show that the failure model of frozen-thawed concrete at various strain rates are different , and with the increasing of strain rates the fracture section of specimens turns to be more flat and many coarse aggregates are damaged;Under the same number of freeze-thaw, with the increasing of strain rate, the compressive strength increases , the peak stain decreases , the peak of the stress-strain curve shows a trend of moving to the upper left , the ascending branch becomes longer whose slope gradually increases, and the descending branch changes in a steepening trend , which shows obvious brittleness;Under same strain rate , as the increase of freeze-thaw cycles , the compressive strength decreases , the peak stain increases , the peak of the stress-strain curve significantly shifts to the below and right , and the area under the stress-strain curve is decreased , which indicates the energy-absorbing capacity decreases;Based on the experimental data , the compressive stress-strain curve equation considering the effects of strain rate and freeze-thaw cycles is proposed .