Abstract: In order to promote the application of BIM technology in tunnel engineering and improve the modeling efficiency of the tunnel BIM model, the parametric modeling of hatbrim slanting cut tunnel portal is studied on the basis of parametric theory. Due to the uniqueness of the irregular ruled surface structure, the hatbrim slanting cut tunnel portal cannot be modeled by simple shape creation and Boolean operations, and the traditional design and modeling process consumes a lot of energy. As a result, in order to improve the design efficiency and provide reference for other engineering structures, the unique structure characteristics and the characteristics of the tunnel design and construction process are studied, the secondary development is conducted by using MicroStation, the parameterization method of creating the tunnel portal is studied, and a program that can efficiently create a hatbrim slanting cut portal model is developed. The program supports dynamic and precise placement and automatic engineering quantity statistics, which will improve the design efficiency and has a very good application effect in actual engineering and reference value for other engineering components.

Key words: tunnel, hatbrim slanting cut tunnel portal, BIM, parametric modeling, secondary development