桩基础动阻抗函数计算方法研究

随着现代工程建设规模的扩大，桩基础得到广泛的应用。针对成层地基上的桩基础，采用两种方法计算了桩基础动阻抗函数：子结构法即离散桩体，采用混合数值算法求解半无限成层地基的格林函数，并结合容积法进行求解；直接法即对桩及桩周围有限域土体进行离散，在边界处施加黏弹性人工边界，进行桩－土系统的整体求解。前一种方法中所采用的混合数值法，该方法计算精度高，且适用于复杂水平成层地基，后一种方法则计算方法简单，适用于大型群桩系统。在数值算例中，计算了半无限地基中单桩、2×2桩基和4×4桩基以及多层水平成层地基中带承台的桩基础的阻抗函数，验证了方法的精度，并讨论了网格尺寸、计算范围选取对计算精度的影响。研究结果对桩基和施工有一定指导意义。

Methods of Dynamic Stiffness Computation for Pile Foundation

With the expansion of the scale of modern engineering construction ,pile foundation has been widely used .Fo-cusing on this problem ,this paper adopted two methods to compute the impedance functions of pile foundations ,first is the substructure method ,in which only the piles are discretized ,and the hybrid numerical algorithm was used to solve the Green’s functions for the layered foundation ,and then the impedance function of pile foundations can be solved combin-ing with the volume method .In the second method ,the piles and the finite field soil around the piles were discretized and the impedance function can be obtained by applying the viscous-elastic artificial boundary on the boundaries .In the former method ,the hybrid numerical algorithm have high accuracy and can be used to solve multi-layered soil .While in the latter method ,the visco-elastic artificial boundary is simple and can be applied in large pile group system .In the nu-merical examples ,the impedance function of single pile ,2 × 2 piles and 4 × 4 piles in semi-infinite foundation and piles foundation with pile cap in layered foundation were calculated to validate the accuracy of the two methods ,and the effect of mesh size ,selection of calculation range on the accuracy were also discussed .The results have certain guiding signifi-cance for the design and construction of piles .