混凝土冻融损伤演化方程的初步建立

摘要

Cyclic freeze-thaw has been recognized as one of the most primary factors leading to internal damage of concrete,and residual strain has traditionally been used to characterize the degree of internal damage in concrete by more and more researchers.In this paper,variation of residual strain was analyzed graphically,and residual strain evolution equation was established.Then the evolution equation and its parameters were discussed and the accuracies of them were verified.It is found that the residual strain of concrete increases with the progress of freeze-thaw damage,and the evolution equation works well to describe the residual strain variation in concrete.The evolution equation can be represented by either a single-segment variation mode or a double-segment variation mode,and the double-segment variation mode is considered to be more suitable to the mechanism of freeze-thaw damage than single-segment variation mode.Furthermore,the validation of residual strain evolution equation can be shown by a high degree agreement of the computed data with the measured ones of the residual strain for each phase of the freeze-thaw cycles.It is of great significance to the service life prediction of concrete subjecting to freeze-thaw cycles.%冻融是造成混凝土内部损伤的重要因素之一,目前越来越多的研究学者使用残余应变来表征由冻融引起的混凝土内部损伤程度.本文通过作图分析残余应变的变化规律,建立了残余应变变化规律演化方程,并对该演化方程及其参数进行了分析和准确性验证.结果显示,混凝土的残余应变随着冻融循环的进行而逐渐增大,残余应变变化规律演化方程能够反映其变化规律;该演化方程可分为单段变化模式和双段变化模式,双段变化模式比单段变化模式更符合冻融损伤的机理;利用该演化方程计算的混凝土各冻融阶段的残余应变计算值和实测值之间具有较高的吻合度,对建立混凝土冻融损伤寿命预测模型具有一定的指导意义.