冻融环境下混凝土双向受压强度与变形特性试验研究

Experimental study of strength and deformation of concrete under biaxial compression in freezing-thawing circumstance

对普通混凝土经冻融后在双向压荷载作用下的变形和强度特性进行了试验研究.试件尺寸为100mm×100mm×100mm.试验过程中测得了混凝土在常态和经过25次、50次、75次冻融循环后在双向受压下的应力-应变关系曲线和双轴强度,分析了主压应力σ3及其对应的应变随冻融循环次数的变化规律,以及在冻融作用后混凝土的二轴强度、应力-应变关系,最大应力处的应力、应变和弹性模量随主压应力比的变化规律,观察了试件的破坏形态,建立了相应的破坏准则.发现普通混凝土经冻融后在双轴压荷载作用下的强度和弹性模量随着冻融循环次数的增加而降低,应变随着冻融循环次数的增加而增大;强度、应变和弹性模量随着主应力比α值的不同而变化的规律及其破坏形态均与常态混凝土基本相同.

Experimental study of the strength and deformation of concrete under biaxial compression in freezing-thawing cycles is carried out. The dimension of the concrete specimens is 100 mm×100 mm×100 mm. The stress-strain curves and the strength of concrete under biaxial compression loading in freezing-thawing cycles of 0,25,50,75 times are obtained respectively. The effect of the number of freezing-thawing cycles on the principal compressive stress σ _3 and corresponding strain ε _3 is analyzed. The effects of the principal stress ratio on the biaxial strength, stress-strain relationship, the strain corresponding peak stress and elastic modulus of the concrete after freezing-thawing cycles are also analyzed. The failure patterns of concrete specimens are described. The failure criterion of concrete under biaxial compression in freezing-thawing cycles is proposed. The strength and elastic modulus of concrete under biaxial compression after freezing-thawing decrease along with the increase of the freezing-thawing cycles, and the strain is on the contrary. The change rule of the strength, strain and elastic modulus along with the principal stress ratio and the failure pattern of the concrete after freezing-thawing are almost the same with those of the normal concrete.