预加静载对大骨料混凝土动态抗压性能的影响

摘要

利用静、动三轴试验机对大骨料混凝土施加不同应变率的单轴压荷载,研究不同的预加静态荷载和应变率(应变率为10-5/s~10-2/s)对大骨料混凝土的动态受压性能影响.试验表明:大骨料混凝土试件在单轴压荷载下为典型的柱状破坏,应变率不会改变试件的破坏形态.随着应变率的提高,混凝土试件表面的裂缝数量逐渐增多,同时存在更多的骨料破坏,混凝土的抗压强度随之增加.在同应变率荷载下,大骨料混凝土的动态抗压强度随着预加初始静态荷载的增加而降低.在初始静态荷载下,大骨料混凝土的应力应变曲线段与静态荷载下相同.当应变率增加时,曲线的斜率即发生变化,其切线模量明显增加,而峰值应变没有明显的改变.%The experiments of larger aggregate concrete under dynamic uniaxial compression are carried out by using a static and dynamic test machine.The relationship between initial static stress,strain rate (ranging from 10-5/s to 10-2/s) and dynamic compression behavior of larger aggregate concrete is analyzed.The experimental results have shown that the strain rate is not changed the failure modes, there is parallel-type for larger aggregate concrete under uniaxial compressive.With the increase of strain rate,the number of distributed cracks on the surfaces of specimen and the broken of coarse aggregates is increased,and the strength of large aggregate concrete is increased.The strength of larger aggregate concrete is decreased with the increase of initial static stress at the same strain rate.Stress-strain curves of large aggregate concrete under the initial static load are similar to that under the static load.The slopes of curves are changed, meanly the tangential modulus is increased significantly,and the peak strains are changed slightly when the strain rate increased.