基于ALE方法的贯入桩周土大变形问题的研究

桩的工作性状是岩土工程中最不确定的问题之一,其中主要原因是对桩在打入加载过程中所造成的桩周土物理状态和应力状态的改变还不是很清楚,对其进行数值模拟时,需要考虑大变形、边界条件改变及桩、土接触问题,一般有限元法在网格剖分上不能解决大变形问题,在边界条件及桩、土界面处理方面不能很好的模拟实际情况。计算实例表明,基于ABAQUS的ALE(任意拉格朗日-欧拉法)方法有效的模拟了贯入时土体的应力变化情况,并得到以下结论: ALE方法能有效避免拉格朗日法有限元分析中网格畸变以及高度扭曲问题,与实际相符合,真实的反映了岩土工程中的弹塑性的变形情况,可以应用到岩土工程中的大变形问题中。以ALE方法为基础对CPT(静力触探试验)贯入试验进行有限元模拟对合理解释CPT的试验的结果是非常有效的。

Large Deformation Meshing Technology for Soil around the Driven Pile Based on ALE Method

The working properties of pile is one of the most uncertain problems in geotechnical engineering. The main reason is that the change of physical condition and stress state of soil around the pile caused by piling is not clear, for a numerical simulation,we should consider the large deformation,the changes in boundary conditions and the contact problems about pile and soil. The general finite element method can not solve the large deformation problem, as the simulation of the actual situation is unable properly to handle boundary conditions and interface between the pile and soil. Calculation examples show that the ALE method(Arbitrary Lagrange Euler)based on ABAQUS is effective to simulate the change of soil stress during geotechnical penetrating, and the following conclusions have been drawn: ALE method can effectively avoid the mesh distortion by Lagrangian method in finite element analysis, as well as high distortion, this method gives result consistent with the actual one, it truly reflects the Elastic-plastic deformation of geotechnical project. The ALE method of ABAQUS can be applied to penetration problems in geotechnical engineering. Having a Finite element simulation of CPT(Cone Penetration Test) based on ALE method, it will give effective explanation to the CPT results.