动 态 响 应 下 海 水 海 洋 骨 料 混 凝 土 受 压 应 力 ‑应 变本 构 关 系 研 究

In order to establish the stress-strain constitutive relationship of seawater marine aggregate-based concrete under compression at high strain rate, the dynamic mechanical properties of seawater-sea sand gravel aggregate concrete and seawater-sea sand coral aggregate concrete were tested by large diameter split Hopkinson pressure bar testing device. The reference datum for comparison of dynamic mechanical properties of each concrete was obtained through static tests for mechanical properties. Based on the results of static and dynamic compressive performance tests, the failure mode and characteristics, stress-strain relationship curves, peak stress and peak strain, dynamic increasing factor (DIF) of compressive strength of seawater marine aggregate-based concrete were obtained; and meanwhile, the influence of strain rate and concrete type on a single performance index was analyzed in depth. The results show that the failure surface of seawater-sea sand gravel aggregate concrete lies in the interface area between gravel and cement slurry, while the failure surface of seawater-sea sand coral aggregate concrete is the shear fracture of coral. The process of static and dynamic compressions of seawater marine aggregate-based concrete are similar, that is: the stress-strain curves basically undergoes the elastic stage, the plastic development stage and the completely plastic failure stage. Strain rate effect has a significant effect on improving the dynamic compressive mechanical properties of seawater marine aggregate-based concrete. Coral as coarse aggregate has a higher strain rate sensitivity than gravel coarse aggregate. Using numerical regression analysis, a DIF prediction model for compressive strength of seawater marine aggregate-based concrete with strain rate as independent variable was established. Based on the piece-type mathematical equations provided in the Code for the Design of Concrete Structures, the unified static and dynamic stress-strain constitutive relationship of seawater marine aggregate-based concrete was established by numerical inversion method.