A new method in which an array of extreme thin elements is used to cope with singular point is presented, calculation program is simplified and a good result is rapidly reached.

This paper discusses fundamental assumption and simplification of the thin-layer element.

5D finite element combined with thin-layer element has been developed to study the dynamic responses of track structure and surrounding ground due to train moving loadings and wave propagation phenomena in three-dimensional ground.

The ground in the near field was modelled with finite elements,while thin layer elements were used to construc.

<Abstrcat>In the Xiluodu Arch Dam aralysis,thin layer element were used for the dam body adjucent to the foundation,different thickness of the thin layer element and the influence of the number of element layers dividing the dam body in the radial direction on the dam stresses obtained have been studied,the principle of grid division for Xiluodu Arch Dam has been determined.

Goodman′s zero thickness element and Desai′s thin layer element for interface model are discussed.

DP model is chosen to consider the non linearity of soil,the changing status non linearity is considered by surface to surface contact element and the geogrid is modeled by the membrane element.

The new model considered that the inclination of cracks of the membrane element of reinforced concrete was between the rotating angle and fixed angle.