考虑温度影响的大体积混凝土应力场分析方法

在大体积混凝土应力场计算中,混凝土的弹性模量和徐变变形都与温度有关,温度场应力场存在耦合现象.根据温度损伤和温度对徐变的影响,建立了考虑温度影响的混凝土弹性模量表达式和徐变应变计算的递推公式.应用粘弹性与损伤耦合和正交各向异性损伤理论,描述了混凝土在高应力水平下的非线性徐变特性和由于微裂缝扩展引起的刚度退化与应变软化,建立了考虑温度影响的大体积混凝土结构应力场分析的有限元表达式.将这一结果应用于沙牌拱坝应力场计算中,考虑温度影响后,发现坝体局部应力可能出现恶化,对开裂控制不利.

An analytical method for stress field of massive concrete considering temperature effect

For the stress field of massive concrete, elastic modulus and the creep of concrete are influenced by temperature, which results in the coupling of thermal field and the stress field. By means of thermal damage and effect of temperature on creep, the expressions for modulus of elasticity of concrete and recursion formula for creep strain are obtained, in which the influence of temperature is considered. The nonlinear creep of concrete under high stress level is described by coupling of visco-elasticity and damage, and the rigidity degeneration and the strain softening due to micro-cracks propagation are described by orthotropic damage theory, by which the FEM expression for stress field of massive concrete structure is put forward by incremental iterative method. By these results, the nonlinear analysis on stress field of Shapai RCC arc dam is performed. The comparisons between the results with temperature effect and those without temperature effect indicate that the local principal stress of dam possibly increases, which is adverse to cracking control of arch dam.