Explosive thermal spalling behavior during fire exposure is one of the major issues in the design of modern reinforced concrete structures. Previous experience on fire disasters indicates that spalling of concrete can have serious structural and economic consequences and must be taken into account in the design for fire. However, spalling mechanisms and their interaction still remain in dispute in the scientific community. In order to shed some light on this phenomenon, a discrete hygro-thermal model of concrete at high temperature called DTemPor3 is proposed and a full coupling scheme between DTemPor3 and the Lattice Discrete Particle Model (LDPM) is performed. The proposed multi-physical coupled model features the effect of pore pressure and temperature on the mechanical response as well as the impact of cracking on moisture mass transport and heat transfer. Simulations of typical spalling experiments show good agreements with data gathered from the literature for both high-performance concrete and ordinary concrete, demonstrating the accuracy of the proposed approach. Cracking localization is found to significantly impede the local pore pressure build-up due to the increase of pore or crack volume. The numerical simulations demonstrate that the spalling phenomenon can be successfully reproduced, only when the effect of thermal stresses is taken in account along with the effect of pore pressure on crack initiation.

火灾中的爆炸性热剥落行为是现代钢筋混凝土结构设计中的主要问题之一。以前在火灾中的经验表明，混凝土剥落会产生严重的结构和经济后果，在设计火灾时必须考虑到这一点。但是，剥落机制及其相互作用仍然在科学界引起争议。为了阐明这一现象，提出了一种称为DTemPor3的混凝土高温湿热模型，并建立了DTemPor3与晶格离散颗粒模型（LDPM）的完全耦合方案。所提出的多物理场耦合模型的特征在于孔隙压力和温度对机械响应的影响，以及裂纹对水分传质和传热的影响。典型的剥落实验的仿真表明，与高性能混凝土和普通混凝土的文献数据相吻合，证明了所提出方法的准确性。发现由于孔或裂缝体积的增加，裂缝的局部化显着阻碍了局部孔隙压力的建立。数值模拟表明，只有在考虑了热应力的影响以及孔隙压力对裂纹萌生的影响的情况下，剥落现象才能成功复制。典型的剥落实验的仿真结果表明，与高性能混凝土和普通混凝土的文献数据相吻合，证明了所提出方法的准确性。发现由于孔或裂缝体积的增加，裂缝的局部化显着阻碍了局部孔隙压力的建立。数值模拟表明，只有在考虑了热应力的影响以及孔隙压力对裂纹萌生的影响的情况下，剥落现象才能成功复制。典型的剥落实验的仿真结果表明，与高性能混凝土和普通混凝土的文献数据相吻合，证明了所提出方法的准确性。发现由于孔或裂缝体积的增加，裂缝的局部化显着阻碍了局部孔隙压力的建立。数值模拟表明，只有在考虑了热应力的影响以及孔隙压力对裂纹萌生的影响的情况下，剥落现象才能成功复制。