本文提出了三维无界元和有限元的耦合方法,即用无界元来模拟远场效应,用有限元模拟近场效应.同时,给出了三维四点无界模型及形函数、位移函数,无界元的单刚矩阵等整套计算公式,编制了三维无界元和等参有限元的耦合程序.该程序具有提高计算精度和节省机时、节省存贮量等优点,是解决岩土工程问题的有效工具. In this paper, the coupling method of three-dimensional unbounded element and finite element is proposed, ie, using the unbounded element to simulate the far-field effect, using the finite element method to simulate the near-field effect. At the same time, the three-dimensional four-point unbounded model and the shape function, displacement function, unbounded element are given. The complete set of calculation formulas such as the single-diffraction matrix, and the coupling program of three-dimensional unbounded element and isoparametric finite element are compiled. This program has the advantages of improving the calculation accuracy, saving machine time, saving storage, and is an effective tool for solving geotechnical engineering problems. .