冲击荷载下全珊瑚混凝土动力特性

以珊瑚砾石、珊瑚砂为粗、细骨料,并拌和海水、水泥制备全珊瑚混凝土.利用分离式霍普金森杆(SHPB)系统进行应变率为30.12~143.32s-1的冲击加载试验,获得全珊瑚混凝土试件的动态单轴压缩应力-应变曲线,并研究了其动态强度增长、能量耗散、破坏模式及破碎分形的应变率效应.结果表明:全珊瑚混凝土试件动态强度增长因子(DIF)与应变率的0.5次方呈线性正相关,且高于同等级普通硅酸盐混凝土;全珊瑚混凝土试件总应变能、弹性能和耗散能均与应变率呈线性正相关,耗散能比率随总应变能增加而增大;不同于普通混凝土胶结面的破坏形态,全珊瑚混凝土试件的破裂面往往贯穿于珊瑚骨料;全珊瑚混凝土试件破碎分形维数与其对数应变率呈线性正相关,利用分形维数可定量表征全珊瑚混凝土的破碎程度.

Dynamic Characteristics of Coral Concrete under Impact Load

Coral gravel and coral sand was respectively used as coarse and fine aggregates,mixed with seawater and cement to prepare coral concrete.The 30.12143.32s-1 strain rate impact loading test was performed using the split Hopkinson bar(SHPB)system.Dynamic uniaxial compressive stress-strain curves of coral concrete under different strain rates were obtained.Meanwhile,the effects of strain rate on dynamic strength growth,energy dissipation,failure mode and fracture fractal were studied.The results show that the dynamic increase factor(DIF)of coral concrete has a linear positive correlation with the 0.5 power of strain rate and is higher than that of same grade ordinary silicate concrete.Total strain energy,elastic energy and dissipated energy all have a linear positive correlation with strain rate,and dissipated energy ratio increases with increase of total energy.Different from the failure of common concrete's cementation surface,coral concrete fracture surface caused by impact load often penetrates through coral aggregate.The fractal dimension of coral concrete fragmentation is linearly and positively correlated with logarithmic strain rate,which can be used to quantitatively characterize the degree of specimen fragmentation.