How to cut toposurface with wall

[HeadbuttJ]

I created a pillbox and a toposurface. I would like to make half of the pillbox constructed inside a hill. How can I cut out the toposurface so that it willt not fill inside the pillbox?

  

[L.Maas · Accepted solution]

You would use the tools on the Massing & Site ribbon. There you can use tool like building pads and/or split surface to modify your toposurface

[barthbradley]

you can use the Building Pad Tool to cut away a portion of the Toposurface.  

...then cover with a Shape-Edited Floor or Roof which uses the same material as the Toposurface.  

[HeadbuttJ]

But if I use the building pad, the toposurface behind the model will become striaght flat which is what I do not want. I want the pillbox to be naturally embedded inside the hill. Dont know if you understand, quite hard to describe in words...

[barthbradley]

Did you read all of what I posted?  I think you missed the last part.  

[martijn_pater]

In addition to the above try a forum search for toposurface + tunnel/tunneling or maybe have a look HERE.

[smartplans]

I have created a foundation wall where the concrete footing is a sweep. This does not cut the toposurface!