双向受压状态下的混凝土率效应试验研究

Experimental Study of Concrete Rate Effect in Biaxial Compression State

利用三峡大学自行研制的大型多功能三轴材料试验机,完成了4种侧应力等级和3个数量级加载速率的C30混凝土立方体试件双向受压试验,系统地探讨了不同侧应力和不同加载速率下混凝土的强度特性及变形特性。研究表明,侧应力和应变速率都能提高混凝土的应变峰值,但侧应力对混凝土的应变峰值的影响较应变速率的影响大;随着侧应力的增加,混凝土的率敏感性逐渐降低;在有侧应力的情况下,随应变速率的增加,混凝土弹性模量变化逐渐减小;随应变速率的增加,应力应变曲线上升段更加陡峭,曲线更加饱满,混凝土剩余强度越来越高;双轴受压情况下,混凝土的应力应变曲线下降段趋势比无侧应力状态下较平缓,随侧应力的增加下降段曲线越来越平缓,混凝土的应力应变曲线更加饱满,峰值点无明显尖峰出现,混凝土剩余强度越来越高。

Biaxial compression experiments of C30 concrete cube specimens subjected to lateral stress of four levels and three orders of magnitude loading rate were completed respectively by using Large- multifunctional Triaxial Testing Machine designed and manufactured by China Three Gorges University. Concrete strength properties and deformation characteristics under the action of different lateral stresses and loading rates were discussed systematically. Results show that both lateral stress and loading rate can improve concrete peak strain, but lateral stress exerts greater influence on the peak strain of concrete. Rate-sensitivity of concrete decreases along with the lateral stress increases. In the case of lateral stress, concrete modulus of elasticity decreases with the increase of strain rate~ the ascending part of stress-strain curve becomes steeper, the curve becomes fuller, and the residual strength becomes higher. In the case of biaxial compression, the descending part of stress-sfrain curve becomea flatter than that of without lateral stress. With the increase of lateral stress, the descending part of stress-strain curve becomes flatter and flatter the curve becomes fuller without significant spike at peak value, and the residual strength becomes higher.