The difference between the two grids for three-dimensional visualization and the element for numerical simulation in geotechnics is obvious due to the variety of data structure. Consequently
it is of much importance to study the integration of three-dimensional visual modeling and mechanical analysis. After dissecting mesh properties of the three-dimensional visualization and the numerical simulation
a method of loose mode which converts three-dimensional grid to FLAC3D element is brought forward. Its application to a submarine tunnel proves that it is reasonable and effective.