变温环境下胶囊混凝土拉压性能及影响因素分析

Analysis of Tensile and Compressive Performance and Influential Parameters of Capsule Concrete Under Variable Environmental Temperatures

胶囊混凝土是一种具备微裂缝自动修复能力的高耐久性工程材料,应用前景广阔.目前对胶囊混凝土力学和自愈性能研究较多,但缺乏对服役环境变温荷载影响的研究.本文研究了荷载与温度共同作用下胶囊混凝土的力学行为,首先采用双线性软化本构关系建立不同胶囊尺寸的胶囊模型和无胶囊混凝土模型,进行单轴拉伸和单轴压缩测试,考察了胶囊尺寸对胶囊混凝土力学行为的影响,随后模拟不同温度下的热源,研究了考虑热传导和温度变化的胶囊混凝土抗压和抗拉性能.数值模拟结果表明,添加胶囊所导致的非均质性使得混凝土拉压强度降低,胶囊尺寸越大,降低幅度越大;一般而言,抗拉强度比抗压强度下降更为明显;由于胶囊和混凝土的热膨胀系数不同,变温环境可使胶囊混凝土的强度降低20%左右,需在材料设计和参数优化中加以考虑.

Capsule concrete is a highly durable engineering material with self-healing capability for micro-cracks,offering broad prospects of applications.Currently,there are considerable researches on the mechanical and self-healing properties of capsule concrete,but there is a lack of research on the influence of variable temperature loads in service environments.In this paper we delve into how capsule concrete behaves under different loads and temperatures.Firstly,various capsule sizes and non-capsule concrete models were tested to assess the effect of capsule size on the mechanical behavior using the bilinear softening constitutive relationship.Subsequently,the compressive and tensile properties of capsule concrete considering thermal conductivity and temperature changes were studied by simulating heat sources at different temperatures.The numerical simulation results indicate that the addition of capsules leads to heterogeneity,resulting in a decrease in the tensile and compressive strength of concrete.The larger the capsule size,the greater the reduction.Generally,the reduction in tensile strength is more pronounced compared to compressive strength.Additionally,due to the different thermal expansion coefficients of capsules and concrete,temperature variations can lead to a reduction in capsule concrete strength of around 20%,which needs to be considered in material design and parameter optimization.