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| A modified stabilized fractional-step algorithm for finite element analysis in saturated soil dynamics |
| Revised:September 25, 2002 |
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| DOI：10.7511/jslx20043051 |
| KeyWord:soil dynamics,fractional-step algorithm,iteration procedure,undrained condition,incompressibility |
| Han Xianhong,Li Xikui*ment,Dalian University of Technology,Dalian 116023,China) |
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| Abstract: |
| Based on the Biot theory, the semi-discretization procedure of the field equations governing evolutions of the displacements u of the solid skeleton and the pore water pressure p_w in deforming saturated porous media results in the u-p_w mixed finite element formulations. In the limit of in compressibility of water and soil grains and zero permeability, the interpolation approximations for the primary variables u and p_w have to fulfill either the Babuska-Brezzi condition or the patch test proposed by Zienkiewicz and Taylor. It is known that the use of elements with equal low order interpolation for u and p_w fails to satisfy the above requirements. The fractional step algorithm introduced as a stabilization technique can circumvent the restrictions to the interpolation functions imposed by the Babuska-Brezzi condition. However, numerical results given by the existing fractional step algorithm show that the spurious oscillation and instability phenomenon in time step integration process still may occur for dynamic problems. A modified version of fractional step algorithm is proposed in the present paper by the introduction of a simple iteration procedure into the existing fractional step algorithm. The numerical difficulties mentioned above can be then effectively alleviated and even eliminated to allow the use of equal low order elements with success for dynamic problems. The numerical results demonstrate the effectiveness and good performance of the proposed modified version of fractional step algorithm. |
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