不同骨料级配混凝土的双轴压强度试验和破坏准则

针对某大坝实际工程,用液压伺服静动态三轴试验系统,对某大坝工程不同骨料级配和尺寸的混凝土试件在双向压荷载作用下的变形和强度特性进行了试验研究。试件采用大坝原级配最大骨料粒径为80mm的立方体试件以及相应的湿筛混凝土试件,尺寸分别为250mm×250mm×250mm、150mm×150mm×150mm、100mm×100mm×100mm。试验过程测得了所有试件两个加载方向的应力和应变以及未加载方向上的变形,探讨了不同级配混凝土的双轴抗压强度、极限变形、应力-应变曲线以及破坏形态的变化规律。试验发现大骨料混凝土在双轴压作用下的极限强度和变形能力要比相应的湿筛小骨料混凝土提高的更多,最后分别在主应力空间和主应变空间建立了不同级配混凝土的破坏准则。

Failure criterion of concrete with different aggregate gradations under biaxial compression

The deformation and strength of concrete with various aggregate gradations and different sizes of specimen under biaxial compression were studied experimentally with a static dynamic hydraulic servo triaxial test system. The maximum dimension of aggregates is 80mm, and corresponding dimensions of cubic specimens are 250mm×250mm×250mm. The specimen dimensions for 40mm wet screened aggregates are 150mm×150mm×150mm and the specimen dimensions for 20mm wet screened aggregates are 100mm×100mm×100mm. The stress and strain in the biaxial loading directions and the free direction are measured in the process of experiment. Based on the test data, the variation rule of the biaxial compressive stress, ultimate deformation, stress strain relationship and the failure patterns were studied. It is found that the enhancement effect of the compressive strength and deformation for concrete with large aggregates under biaxial compression is stronger than those of wet screened specimens. The expression of failure criterion for concrete with different gradations is established both in normal stress space and in normal strain space by regression analysis according to the test data.