水饱和混凝土静力抗拉强度降低细观机理及本构模型

试验研究表明裂纹及孔隙中的自由水降低了混凝土的静力抗拉强度.本文根据表面物理学及水的特性探讨了自由水降低混凝土静力抗拉强度的细观机理,并根据拉伸荷载作用下混凝土中微裂纹的扩展规律和不同阶段微裂纹引起的混凝土非弹性柔度张量的变化,考虑自由水的作用,利用线弹性断裂力学建立了饱和混凝土的受拉本构模型.理论计算与试验应力-应变关系曲线的对比表明:理论模型可以较好地反映饱和混凝土的受拉力学特性.

Mesomechanism of Tensile Strength Reduction and Tension Constitutive Model of Saturated Concrete

Experiment shows that the static tensile Strength of concrete is reduced by free water in the cracks and pores. Based on surface physics and character of water, the mesomechanism of tensile strength reduction of saturated concrete is analyzed. Free water in the cracks decreases the surface energy of solid, or accelerates the damage of concrete in tension, which causes the reduction of tensile strength. Inelastic deformation of concrete is caused by cracks, and cracks in different loading level contribute different inelastic deformation to concrete. In terms of development regularity of cracks in tension and effect of free water, the constitutive equation of saturated concrete in tension is put forward based on linear elastic fracture mechanics. The results of theoretic model agree well with stress strain relationship of experiment, which suggests that the theory in this paper can reflect the tension characteristics of saturated concrete.