温度对混凝土力学性质影响的颗粒流模拟研究

为探索混凝土在热力耦合作用下的宏观力学性质和微裂纹的变化规律,采用PFC软件中的热模块,对5种温度下的混凝土试块进行了数值模拟分析。研究结果表明:(1)温度和峰值强度呈现负相关关系,单轴抗压强度和弹性模量随温度的变化服从幂函数关系,且温度对于强度和变形参数的影响不同,强度相较于变化参数而言,对温度更加敏感。(2)随着温度的升高,由热破裂所造成的损伤不断增加,热损伤集中在界面过渡区。随着温度的升高,混凝土的破坏模式由剪切破坏逐渐转变为劈裂破坏。(3)600℃属于临界温度,在600℃之前,宏观力学性质和微裂纹扩展均变化剧烈;超过600℃以后,宏观力学性质的劣化和微裂纹的发展均放缓。

Analysis of the effect of heating on concrete mechanical properties based on particle flow code

In order to explore the macro-mechanical properties and micro-crack changes of concrete under thermal-mechanical coupling，the thermal module in PFC software is used to numerically analyze the concrete test blocks at 5 temperatures． The results show that: ( 1) As the temperature increases，the uniaxial compressive strength gradually decreases，and the change of the uniaxial compressive strength and elastic modulus of concrete with temperature follows a power function relationship． ( 2) As the temperature increases，the thermal damage caused by the temperature to the concrete continues to increase，and the thermal damage is mainly concentrated in the interface transition area． As the temperature increases，the failure mode of concrete under uniaxial compression gradually changes from shear failure to splitting failure． ( 3) In the model，about 600 ℃ belongs to the critical temperature of heating． The macro-mechanical properties and micro-crack propagation change drastically above 600 ℃， and the deterioration of macro-mechanical properties and the development of micro-cracks slow down below 600 ℃ ． The conclusion can provide some reference and guidance for the design and construction of concrete structures．