双轴受压状态下混凝土动态抗压特性试验研究

Experimental study on dynamic compressive properties of concrete under biaxial compression

由于多轴试验装置的高技术性,混凝土在复杂应力状态下的动力研究相对偏少。为研究双轴受压状态下混凝土的动态抗压特性,采用真三轴静动综合加载试验系统,进行了5种双轴受压状态下混凝土立方体试件的冲击压缩试验,分别从应力应变曲线特征、强度特性和变形特性等方面分析双轴受压状态对混凝土动力响应的影响规律。结果表明:双轴受压状态下,混凝土承受冲击荷载时呈现典型的脆性破坏,应力应变曲线初期无明显压实挤密阶段;主轴压比一定时,随单侧压比的增大,混凝土的动态抗压强度呈现出先升高后降低的趋势,峰值应变和平均应变率皆呈现出先减小后增大的趋势;双轴受压对混凝土有加固约束作用,因而提高了其动态抗压强度和抗变形能力,主轴压比∶单侧压比为0.4∶0.4时作用效果最佳。

Due to the high technicality of the multi-axial test equipment,the dynamic research of concrete under complex stress condition is relatively less.In order to study the dynamic compressive properties of concrete under biaxial compression,the impact compression tests of concrete cube specimens under five types of biaxial compression conditions were carried out by using the true triaxial static and dynamic comprehensive loading test system.The effects of biaxial compression on the dynamic response of concrete are analyzed from the aspects of stress-strain curve characteristics,strength characteristics and deformation characteristics.The results show that:under biaxial compression,the concrete exhibits typical brittle failure when subjected to impact load,and there is no obvious compaction stage in the initial stage of the stress-strain curve;when the spindle pressure ratio is fixed,with the increase of the unilateral pressure ratio,the dynamic compressive strength of concrete shows a trend of first increasing and then decreasing,and the peak strain and average strain rate show a trend of first decreasing and then increasing;biaxial compression has the effect of reinforcement and restraint on concrete,which improves its dynamic compressive strength and deformation resistance.When the ratio of spindle pressure ratio to unilateral pressure ratio is 0.4∶0.4,the effect is the best.