采用大型混凝土静、动态三轴液压伺服试验系统,比较了大骨料混凝土试件和湿筛二级配混凝土试件在动态三轴拉压压应力状态下的强度特征.结果表明:2种试件的破坏均为典型的拉伸破坏,裂缝垂直于拉应力方向;动态抗拉强度随应变率的增大而增大,随压应力的增大而减小;抗拉强度增长系数与应变率比的对数呈线性关系;大骨料混凝土试件的动态抗拉强度及其对应变率的敏感性均比湿筛二级配混凝土试件的要小.在八面体应力空间中建立了破坏准则,为大体积结构的非线性分析和抗震设计提供了试验依据.
Strengths of large aggregate concretes and the corresponding wetscreenea concretes were stuoteu experimentally. Specimens were subjected to dynamic triaxial compressioncompressiontension stress, using large concrete static and dynamic triaxial servo test system. Results show that fallures of the two kinds of concretes are typical tensile failures, and the cracks are perpendicular to the tensile stress direc tion. Their dynamic tensile strength increases with the increase of strain rate, and decreases with the in crease of compressive stress. The increasing coefficient of tensile strength and the logarithm of strain rate ratio are in linear relationship. Dynamic tensile strength and its sensitivity to strain rate of large aggregate concretes are lower than those of the wetscreened concretes. By fitting the experimental data, failure cri teria in octahedral stress space were established, which provides an experimental basis for nonlinear analy sis and seismic design of mass concrete structure.