单轴循环加载下多孔弹性混合料孔隙结构演变

Evolution of pore structure within porous elastic mixture under unilateral cyclic loading

采用单轴循环加载试验和CT扫描图像分析方法,研究不同加载阶段多孔弹性混合料内部的孔隙结构(孔隙数量和空隙率)演变过程。研究结果表明:单轴循环加载导致试件总体高度减小,试件下部体积增大直至在试件高为10~60 mm区域内发生膨胀破坏。多孔弹性混合料的累积变形经历变形初期、前期、中期和后期4个阶段。在变形初期和变形前期,直径[0.5,1]mm和直径[1,2]mm的孔隙数量减少,变形中期大孔隙开始相互连通,导致直径[2,5]mm的孔隙数量开始减少,变形后期的破坏集中在直径[0.5,1]mm和直径[1,2]mm的孔隙。整个变形期内试件高度在70 mm以下的区域空隙率逐渐增大,孔隙数量逐渐减小,而在试件高度在70 mm以上区域内孔隙结构变化不大。

The evolution process of pore structure,including pore number and air void,within porous elastic mixture at different loading stages were investigated by the unilateral cyclic loading test and CT scanning image analysis.The results show that the unilateral cyclic loading causes the reduction of specimen height,the volume dilation of specimen at lower part and expansion failure at the 10-60 mm region along the specimen height.The cumulative deformation of porous elastic mixture undergoes four stages,including the initial deformation stage,the early deformation stage,the middle deformation stage and the last deformation stage.During the initial and early deformation stages,the number of pores with the diameters of[0.5,1]mm and[1,2]mm decreases,followed by the gradual interconnection of large pores at the middle deformation stage,which reduces the number of pores with diameters of[2,5]mm.It is the pores with the diameters of[0.5,1]mm and[1,2]mm that are mostly damaged during the last deformation stage.During the whole deformation period,the air void of the specimen within the height of 70 mm gradually increases while the pore number gradually decreases.But for the specimen region above the height of 70 mm,the pore structure changes slightly.