大骨料混凝土在双轴压应力状态下的变形和强度试验研究

Experimental Study on Deformation and Strength of Mass Concrete under Biaxial Compression

利用大连理工大学自行研制改造的液压伺服静、动态三轴试验系统对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.试验所用试件有3种:采用大坝原级配最大骨料粒径为80 mm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×250 mm,150 mm×150 mm×150 mm和100 mm×100 mm×100 mm.试验过程中,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侧向变形,并根据试验结果,系统地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,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,这为水工大体积混凝土按多轴强度理论进行设计提供了试验依据.

Experimental study on the deformation and strength of various aggregate grading and sized concrete specimens under biaxial compression was carried out with the static-dynamic hydraulic servo tri-axial test system that was designed and manufactured at the Dalian University of Technology （DUT）. Tests were conducted on cubes of 250 mm × 250 mm × 250 mm fabricated with dam concrete （ maximum aggregate of 80 mm）, 150 mm × 150 mm × 150 mm cubes and 100 mm × 100 mm × 100 mm cubes which were made with the wet-screened components of dam concrete. The stresses and strains at the biaxial loading direction and the latend deformations at the free direction of all specimens are recorded during the tests. Based on the test data, the change nile of the biaxial compressive stress, ultimate deformation, stress-strain and the failure patterns were studied systematically. Test results indicate that the enhancement effect of the compressive strength and deformation of the mass concrete under biaxial compression become stronger than that of the wet-screened specimens. Failure criterion of different graded concrete under biaxial compression has been both established in normal stress space and in normal strain space. It provides effective references for the design and safety evaluation of the massive hydraulic structures in which the multi-axial strength of the concrete must be taken into consideration.