摘要
基于对混凝土细观结构的认识,从材料力学性质的非均匀特性出发,对不同力学边界条件下的混凝土快速升温诱发热开裂的过程进行了数值模拟,数值模拟中假定混凝土是由砂浆基质、骨料及其他们之间的界面组成的三相复合材料,并以最大拉应变准则和摩尔库仑准则作为损伤发生的阀值。数值模拟再现了混凝土内部微裂纹萌生、沿骨料与砂浆之间的界面扩展、贯穿砂浆基体的热开裂全过程。快速升温下温度梯度以及热力学不匹配联合作用下的这种热开裂裂纹,是混凝土热破坏过程中的主要裂纹形式之一,除了材料非均匀特性之外,热开裂裂纹的萌生、扩展也是促成混凝土热爆裂发生的不确定性的原因之一:在致使混凝土热破坏的同时,其本身也是水(汽)压力释放的主要通道,在一定程度上缓解热爆裂。数值计算结果对混凝土高温热破坏的研究具有参考价值。
Based on the knowledge of heterogeneous characteristics of concrete at mesoscopic level, several numerical simulation are conducted to investigate the thermal cracking of concrete exposed to rapidly rising temperature.ha numerical model, the concrete is assumed to be composed of matrix,aggregates and interfaces between them.The maximum tensile strain criterion and Mohr-Coulomb criterion are utilized as damage threshold.Numerical results represent the complete fracture process of concrete materials that include the initiation, propagation, and coalescence of microcracks and cracking patterns associated with different loading stages and loading conditions.The investigations results show that the heterogeneous characteristics and thermal cracking are the main reason to induce the thermal spalling and uncertainty of explosive spalling in concrete.Numerical investigation is meaningful for estimating the failure of concrete subjected to high temperature.
出处
《混凝土》
CAS
CSCD
北大核心
2008年第10期38-41,44,共5页
Concrete
基金
国家自然科学基金(50778084)
关键词
混凝土
高温
细观损伤
热开裂
数值模拟
concrete
high temperature
meso-scale damage
thermal cracking
numerical simulation
