Considering the significance of sulfate attack to structure durability and frequent existence of multiaxial loadings, it is relevant to study the triaxial mechanical behavior of sulfate-deteriorated cementitious materials. The triaxial compression tests with three confining pressures were conducted in previous study. To give a reliable constitutive model, this research investigated the triaxial mechanical behavior of sulfate-deteriorated mortar in experimental and modeling aspects. All stress–strain curves of the mortar samples immersed in 5% Na2SO4 solution up to 270 d were shown and analyzed. The ingress of sulfate decreased the axial strain at improvement stage, but slightly increased the strain at deterioration stage. The volume of mortar sample changed from contraction to dilation with loading, indicating a non-associated flow rule. A nearly linear relationship between the square root of triaxial failure stress and elastic modulus of mortar was observed, proved by other research results as well. The lateral confinement attenuated the negative effect of sulfate deterioration on the two mechanical indexes. On the basis of elastoplasticity theory and experimental results, an elastoplastic model considering sulfate deterioration was proposed. The effect of sulfate deterioration was implemented to the elastic modulus, failure criterion and hardening law through 2nd polynomial. Numerical simulations showed that the proposed model can well reproduce the compression behavior of sulfate-deteriorated mortar with different confining pressures.

中文翻译：

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硫酸盐劣化砂浆三轴力学行为试验与建模研究

考虑到硫酸盐侵蚀对结构耐久性的重要性和多轴载荷的频繁存在，研究硫酸盐劣化胶凝材料的三轴力学行为具有重要意义。先前的研究中进行了三个围压的三轴压缩试验。为了给出一个可靠的本构模型，本研究在实验和建模方面研究了硫酸盐劣化砂浆的三轴力学行为。显示并分析了浸泡在 5% Na2SO4 溶液中长达 270 天的砂浆样品的所有应力-应变曲线。硫酸盐的进入使改善阶段的轴向应变减小，而劣化阶段的应变略有增加。砂浆样品的体积随载荷从收缩变为膨胀，表明存在非关联的流动规律。观察到三轴破坏应力的平方根与砂浆的弹性模量之间几乎呈线性关系，其他研究结果也证明了这一点。横向约束减弱了硫酸盐劣化对两个力学指标的负面影响。在弹塑性理论和实验结果的基础上，提出了考虑硫酸盐劣化的弹塑性模型。硫酸盐劣化对弹性模量、破坏准则和硬化规律的影响通过第二多项式实现。数值模拟表明，该模型可以很好地再现不同围压条件下硫酸盐劣化砂浆的压缩行为。其他研究结果也证明了这一点。横向约束减弱了硫酸盐劣化对两个力学指标的负面影响。在弹塑性理论和实验结果的基础上，提出了考虑硫酸盐劣化的弹塑性模型。硫酸盐劣化对弹性模量、破坏准则和硬化规律的影响通过第二多项式实现。数值模拟表明，该模型可以很好地再现不同围压条件下硫酸盐劣化砂浆的压缩行为。其他研究结果也证明了这一点。横向约束减弱了硫酸盐劣化对两个力学指标的负面影响。在弹塑性理论和实验结果的基础上，提出了考虑硫酸盐劣化的弹塑性模型。硫酸盐劣化对弹性模量、破坏准则和硬化规律的影响通过第二多项式实现。数值模拟表明，该模型可以很好地再现不同围压条件下硫酸盐劣化砂浆的压缩行为。硫酸盐劣化对弹性模量、破坏准则和硬化规律的影响通过第二多项式实现。数值模拟表明，该模型可以很好地再现不同围压条件下硫酸盐劣化砂浆的压缩行为。硫酸盐劣化对弹性模量、破坏准则和硬化规律的影响通过第二多项式实现。数值模拟表明，该模型可以很好地再现不同围压条件下硫酸盐劣化砂浆的压缩行为。