湿筛二级配大坝混凝土双轴应力下的强度特性

Strength Properties of Wet-screened Two-graded Aggregate Concrete for High Arch Dam Under Biaxial Stress

采用大连理工大学自行研制的电液伺服三轴试验系统,结合溪洛渡大坝实际工程,对大坝湿筛二级配混凝土进行了单轴拉、单轴压、双轴拉压、双轴压压及双轴拉拉应力状态下的强度特性试验研究。在进行双轴拉压试验时,提出了一种新的加载方式,即双钢板-塑料毛刷组合连接方式。试验结果表明:该加载方式能使试件端部拉应力传递更加均匀,有效消除了拉端粘贴钢板对试件受压变形的约束作用,提高了试验精度,同时能大大提高试验效率;根据试验结果建立的双轴应力状态下的主应力空间破坏准则可以为大体积水工混凝土结构设计及非线性分析提供参考。

Combined with the Xiluodu High Arch Dam project, authors presented an test study on the strength property of wet-screened two-graded aggregate concrete for high arch dam under uniaxial tension, uniaxial compression, biaxial tension-compression, biaxial compression and biaxial tension stress by using the electro-hydraulic servo-controlled triaxial test machine of Dalian University of Technology. A new test loading method was developed for evaluating the concrete strength under tension-compression stress, in which a glued double-plated manner combined with plastic brushes was adopted. The test results show that this new method can make the transformed stress more uniform, and can effectively eliminate the compression deformation restraint of the bonded steel to the concrete specimen at the tension end. Meanwhile, it can improve the test precision and can increase the test efficiency. The appropriate failure criterion developed in the principal stress space for biaxial stress states based on the test results can provide the references for mass hydraulic concrete structural design and nonlinear analysis.