活性粉末混凝土RPC(Reactive Powder Concrete)是一种新型超高性能混凝土材料,作为新材料在铁路工程中应用的基础,对其多轴力学性能进行研究有重要意义.在6种不同的应力比下,对活性粉末混凝土立方体试件进行三轴定侧压加载试验,分析活性粉末混凝土在三轴压下的强度特征、变形性能及破坏形态.结果表明:在本研究的应力比范围内,活性粉末混凝土的破坏模式主要为斜剪破坏;三轴抗压强度约为单轴抗压强度的3~4倍,抗压强度最大值出现在第二主应力与第三主应力比值为0.25时;三轴主压向峰值应变为单轴压峰值应变的5~10倍,随着第二主应力的增大,主压向峰值应变逐渐增大;主压向的应力-应变曲线在峰值后没有下降段,而是出现了明显的"应力平台";根据实测的三轴抗压强度,建议了适用于活性粉末混凝土的八面体空间破坏准则的相关参数.%Reactive Powder Concrete(RPC) is a new generation of ultra-high performance sustainable construction material.The study of the multiaxial mechanical properties of the new material as the basis of the application of new materials in railway engineering is highly important.In this paper,RPC cubes were tested under triaxial compression in 6 different stress ratios to analyze the strength characteristics,deformation behavior and failure modes of RPC under triaxial compression.The results showed that the failure mode of RPC was oblique shear failure within the stress ratio of this study.The triaxial compressive strength of RPC was about 3 to 4 times that of the uniaxial compressive strength.The triaxial compressive strength reached its maximum when the ratio between the second stress and the triaxial compressive strength was 0.25.The peak strain of triaxial compression was 5 to 10 times that of the uniaxial compression.With the increase of the second principal stress,the triaxial compression peak strain gradually increased.Instead of "post-peak descending stage" of stress-strain curves,obvious "stress platform" was observed.Relevant parameters of spatial failure criterion in octahedral stress were suggested according to the measured triaxial compressive strength data.
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