多轴应力条件下碾压混凝土层面抗剪强度试验研究

Mechanical properties of roller compacted concrete under multiaxial stress state

针对碾压混凝土重力坝和拱坝等坝体真实的工作受力状况,对碾压混凝土拱坝所用的二级配混凝土材料成型的本体、层面处理和层面不处理试件,进行了单轴及多轴应力条件下的剪切试验研究。试件尺寸为150mm×150mm×150mm,试验比较了不同应力状态对本体和含层面试件的抗剪强度和变形特性的影响。结果表明:在低应力压剪和压压剪应力状态下,所有试件抗剪强度和极限变形均有所提高;在有拉应力存在的状态下,所有试件抗剪强度均有所降低;复合应力状态下三种试件强度和变形特性有一定的差异。在以上试验基础上提出了碾压混凝土在复杂应力状态下的多轴剪切强度破坏准则。

Considering the true mechanical states of the concrete in roller compacted gravity and arch dam,a group of direct and multiaxial shear experiments of the roller compacted concrete（RCC） specimens were carried out with two graded-aggregates obtained from a high arch dam.The dimensions of the specimens are 150mm×150mm×150mm and these specimens are of three kinds,including the body specimens,layer-treated specimens and layer-untreated specimens.The shear strength and deformation characteristics of these three kinds of specimen under different stress states were analyzed systematically.Test results indicate that the shear strength and ultimate deformation of RCC increase under biaxial compression-shear and triaxial compression-compression-shear if the stress is not high.While under tension-shear and tension-compression-shear the shear strength and ultimate deformation of RCC decrease sharply.There are also some differences in the strength and deformation characteristics of these three types of specimens under complex stress states.By regression of the tests results,respective failure criterions for RCC under different combined loads are proposed.