土木工程结构混凝土寿命预测的损伤演化方程

Damage evolution equation for service life prediction of concrete structures in key civil engineering

借助损伤力学的原理,通过系统实验,研究了混凝土在冻融与腐蚀条件下损伤失效过程的规律与特点.建立了具有普适意义的混凝土损伤演化方程,提出了损伤速度和损伤加速度的新概念,并提出了一套预测混凝土结构使用寿命的基本方法与理论体系,为重大土木工程结构混凝土的寿命预测提供了一种新方法.此外,通过专门设计的(35%弯曲荷载+冻融)双重因素和(35%弯曲荷载+冻融+3.5%NaCl溶液腐蚀+5%Na2SO4溶液腐蚀)多重因素等耐久性实验,重点研究了国家重点工程润扬大桥的主体结构混凝土的使用寿命预测问题.结果表明,润扬大桥的箱梁、索塔、墩身和锚碇采用高强高性能混凝土以后,其预期使用寿命均能达到100年设计要求.

Based on results of systematic experiments, damage evolvement and the characters of concrete subjected to freezing-thawing cycles and/or chemical attack were investigated by principle of damage mechanics. Two new concepts, namely, damage velocity and damage acceleration are defined and a damage development equation, which can be universally applied, is established. A systematic theory, which serves for service life prediction of key concrete structures, is presented, and the basic operation is also illustrated. Service life prediction of a national key project, the Runyang bridge across Yangtse Rive, was studied via specially designed durability experiments, in which double damage factors (flexural load and freezing-thawing cycles), and multiple damage factors (flexural load, freezing-thawing cycles, NaCl and Na2SO4 solution attack) were involved. Results show that service life of Runyang bridge across Yangtse Rive can meet the 100 years requirement since high strength and high performance concrete are adopted.