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采用改进的扩展有限元法(Extended Finite Element Method,XFEM),即引入虚结点的XFEM,在静力功能基础上实现了动力断裂分析功能,并用于强震中结构多条裂缝的同时扩展分析。采用混凝土Ⅰ型和Ⅰ-Ⅱ混合型动力断裂试验进行了精度验证,然后将该方法应用于Koyna坝的地震开裂分析。结果表明,这一方法在求解混凝土Ⅰ型和Ⅰ-Ⅱ混合型动力断裂问题方面具有良好精度,其避免了网格不断重剖分的问题,也无需采用开裂单元的子域积分来描述非连续位移场,即可实现单元内连续断裂过程的模拟。
A modified Extended Finite Element Method (XFEM) is introduced, in which the XFEM with virtual nodes is introduced to realize the dynamic fracture analysis based on the static function. The XFEM is also used to analyze the simultaneous expansion of multiple fractures in strong earthquakes. The accuracy of hybrid type Ⅰ and type Ⅰ-Ⅱ dynamic fracture tests was verified, and then the method was applied to the seismic cracking analysis of Koyna dam. The results show that this method has good accuracy in solving the hybrid type Ⅰ and type Ⅱ-Ⅱ dynamic fracture problems, which avoids the problem of continuous meshing and does not need to use the sub-region integral of the cracked element to describe the non-continuous Displacement field, you can achieve the unit continuous fracture process simulation.