基于单元嵌入技术和弹性比拟的含裂纹混凝土三维渗流模拟方法

THREE-DIMESIONAL SEEPAGE ANALYSIS FOR CRACKED CONCRETE BASED ON EMBEDDED ELEMENTS AND ELASTIC ANALOGY

混凝土结构在服役过程中受到力学荷载和环境因素的影响会产生裂纹,裂纹的产生、扩展和连通会显著影响混凝土的渗透性。该文将混凝土看作由基体和裂纹夹杂二相组成的复合材料,采用单元嵌入技术,有效地解决了基于连续网格的实体裂纹模型存在的网格协调问题。考虑到弹性问题与渗流问题在数学上的相似性,通过对含裂纹混凝土位移场和应力场的弹性比拟,得到相应的渗流场。在计算过程中,分别研究了渗透系数、网格尺寸及裂纹张开度对渗流场的影响,以及该文方法对多裂纹体的适用性。计算结果表明:该文的方法与实体裂纹模型的渗流场计算结果吻合,保证了结果的正确性。同时也降低了三维裂纹建模的难度,提高了计算的效率。

Over the serving period, cracks are usually induced in structural concrete by mechanical loading or environmental effects. Initiation, expanding and interconnection of cracks obviously increase the permeability of the cracked concrete. The conventional seepage analysis method associated with continuous solid elements encounters difficulties in mesh coordination. In this study, a new method, named the embedded element technique, was adopted to solve this problem. Considering the mathematical similarity between elasticity and seepage problem, water head and velocity field within the cracked concrete can be obtained by the analogy of the corresponding displacement and stress field. The effects of component permeability, element size, and crack opening displacement on the seepage field were discussed. Comparing the results obtained by the continuous model and the embedded element model, it is seen that, apart from providing satisfying results, the new method simplifies the finite element meshing and increases the calculation efficiency.