Computer aided geometric design for excavating boundary lines and backfilling boundary lines of the side slope

In this paper, the parameter equation of radius-varied circular envelope is used to establish the frequently used parameter equations of side slope surface, which are produced when the vertex of a cone moves along a cylindrical spiral line, a level arc, a spatial line or a level line. With the assistance of computer and AutoCAD, the excavating boundary lines and the backfilling boundary lines of side slope can be drawn out accurately. The boundary line is the connecting line of dots where the contour lines of the side slope intersect the topography contour lines in the same elevation. Thus, the paper provide a method of computer aided geometric design in planning and designing roads, banks, trenches and dams, and also carry out the computer aided drawing.