How to cut Solid with Terrain Surface

[s.iwasaki]

The ultimate goal is to determine the shape of the cut slope using soil volume calculations in Generative Design.
I intend to establish indicators other than soil volume.

Creation of slopes along topography and calculation of excavated soil volume

I am looking to create a slope that follows the topography. We were able to create a slope surface along the centerline of the road, as shown in the first picture. However, I cannot figure out how to cut this Surface so that it rubs against the terrain. What I want to do is to then calculate the excavated soil volume from the slope surface and the existing terrain surface. I tried Geometry.Intersect and Geometry.Split but did not get the results I wanted. To do this, I am first trying to ge…

I was hoping to cut out Solid with Terrain and Corridor Surfaces to get the soil volume.
If not this way, what is the best way?