Intermediate algorithm: First, it can be proved that the intersection piece is not completely solid (that is, the line 1200mm above the cushion will not pass through the hollow area in the concrete pipe). First, fill the line 1200mm above the cushion, and make a vertical line halfway through the center of the circle.
The algorithm of intersection block is to subtract the hollow sector area from the whole sector area.
Sector area algorithm: sector central angle =2 * arcsine 300/900, sector area =π*(900/2) square * sector central angle /360.
The area multiplied by the length is the volume of the intersection.
Take the data yourself, it is not convenient to calculate at hand.