PURPOSE: To make it possible to perform an optimum calculation for foundation work with a very simple operation by preparing plural rotary discs, where required related graphs are displayed, and synthesizing properly respective values on graphs appearing on these discs.

CONSTITUTION: The scale for earth cover depth H is provided in the Y axis positive direction of rotary plate-shaped material 1, and the scale for overall earth pressure P applied to a buried pipe is provided in the X axis, and related curves for application of respective surface loads IWIV are expressed in the first quadrant. The scale for static water pressure P' applied into the buried pipe is provided in the Y axis negative direction, and the fourth quadrant is transparent. The scale for the overall earth pressure applied to the buried pipe is provided on the Y axis of rotary plate- shape material 2, and the scale for the static water pressure applied into the buries pipe is provided on the X-axis. First, an overall earth pressure is obtained by the surface load and a pipe burying depth on a basis of plate-shape material 1. Next, intersections between the static water pressure and the overall earth pressure are platted in the fourth quadrant on a basis of the used pipeline form. Next, each quadrant of plate-shaped material 2 is superposed onto the reverse face of the fourth quadrant, and points plotted previously are projected onto plate-shape material 2 to confirm the design support angle of foundation and the passive resistance coefficient of re-buried earth or banking.