碾压混凝土在温度应力联合作用下的损伤准则

目的为了确定碾压混凝土在温度应力联合作用下的损伤准则.方法基于最小耗能原理,针对碾压混凝土是一种耗散型材料,认为在其损伤过程中,伴随着能量的耗散,且损伤将总是在相应给定条件(损伤准则)的约束下,以其最容易发生损伤的方式发生和进行,同时假设碾压混凝土仅存在热耗散和损伤耗散,而忽略由内变量和湿度等其他因素所造成的耗散,建立了能反映碾压混凝土横观各向同性性质,在温度应力联合作用下的损伤准则.结果碾压混凝土热耗散和损伤耗散累积到一定程度时,损伤破坏就会发生,且随着热流密度矢量和温度梯度增大,碾压混凝土发生损伤破坏的应力水平将降低,如碾压混凝土是一个等温变化过程,则损伤完全取决于应力水平.这与相关试验结论是吻合的.结论在损伤准则中考虑温度的影响是必要的;碾压混凝土具有横向各向同性性质,若采用常态混凝土损伤准则,与碾压混凝土的材料特性不符,弹性模量与泊松比对损伤准则均有影响.

Analysis of Damage of RCC under United Actions of Temperature and Stress

The paper intends to analyse the damage of RCC under united actions of temperature and stress.Roller compacted concrete(RCC) is a kind of dissipation material.So based on the principle of least energy dissipation,this process of RCC damage is regarded as a process of energy dissipation,thus damage process will be carried out by means of least energy dissipation corresponding to the condition of restraint.Assuming that there are heat energy and damage dissipation only,a damage criterion of RCC under united action of temperature and stress is established.This damage criterion reflects the character of RCC,and shows that stress degree of RCC damage decreasing with heat current density vector and temperature gradient augmenting.If this process of RCC damage is in constant temperature,the damage completely depends on stress degree,which accords with the result of experiment.It is necessary to consider the influence of temperature on damage.If damage criterion of normal concrete is adopted,it can not reflect transversal isotropy character of RCC,because elastic modulus and poisson ratio have influence on damage.