基于双标量损伤黏聚裂缝模型的混凝土单轴受压裂缝扩展分析

Analysis of crack propagation of concrete under uniaxial compression based on double scalar variables damage-based cohesive crack model

为了解决混凝土单轴受压裂缝扩展问题,将损伤力学的观点引入到黏聚裂缝模型的描述中,在热力学的框架上提出了一类双标量损伤黏聚裂缝模型。根据试验数据拟合了受拉及受剪两种损伤演化曲线,并将库伦定理引入到受剪损伤演化曲线中,使得本文提出的黏聚裂缝模型更为完善,不仅能描述混凝土单一(I、II型)裂缝模式,同时还能描述复合(拉剪及压剪)裂缝模式下裂缝面间黏聚应力与相对位移之间的关系。在数值方法上,采用非规则界面单元方法:在试块内随机划分三角网格,并在所有三角单元边界上嵌入界面单元,使得裂缝能在试件全局内随机扩展。结合以上两种方法,对混凝土单轴受压裂缝扩展进行数值模拟,数值模拟结果能较好的描述裂缝扩展过程中出现的多裂缝同时扩展、裂缝贯通汇集以及横向膨胀变形等现象。

In order to solve the problem for crack propagation of concrete under uniaxial compression, theviewpoint of damage mechanics is introduced into the description of the cohesive crack model, and a kindof double scalar variables damage-based cohesive crack model is presented in the framework of thermody-namics. Tensile and shear damage evolution curves is fitted according to the experimental data, and Cou-lomb＇s law is introduced into the shear damage evolution curve, which makes the proposed cohesive crackmodel more perfect. It can synthetically describe the stress-relative displacement relationship between thecrack surface, not only for the single（Mode Ⅰ and Ⅱ） crack mode, but also the mixed（tension-shearand compression-shear） crack mode. In the numerical method, irregular interface element method is usedto divide the triangle mesh randomly and then embed the interface element on the boundary of all triangu-lar elements,so that the crack can propagate in the global of the specimen. Combined with the above twomethods, the numerical simulation of the crack propagation of concrete under uniaxial the compression iscarried out. Phenomena including multi-cracking,crack coalescence,and lateral expansion deformation dur-ing crack propagation of concrete can be described in the numerical simulation.