Foundations

Excavation within Excavation

When you need to define a building excavation, you often must choose whether to place all levels in the same layer or use multiple layers (a form of excavation within excavation). For example, you can place foundations on separate layers. You construct the foundations, for instance, on layer nn: Foundations. The construction principle is the same as for the excavation's surface layer. You construct a boundary contour for the bottom of the foundation and check Cut/fill for it.

Figure caption: A = Surface layer defined as rock layer, B = Foundation layer, C = Soil, D = Rock

The difference is that you want to stop the foundation's cutting surfaces against the excavation's surface layer. You solve this by defining the excavation's surface layer as a rock layer. As you described in the section about the excavation's surface, you can use parameters 0510 Rock cut slope and 0610 Soil cut slope for the side surfaces.

Note

These parameters will stop against physical layers as described in this section. A consequence is that the cuts can stop before they reach the excavation's surface. It may therefore be more appropriate to use other parameters, for example 0110: Roadway width and 0111: Cross slope, and set the width so large that you are sure the surface will cut the excavation's surface.

If you have many foundations on one layer, it may be more appropriate to set method Auto on all boundary contours and edit the parameters with the same Cut/fill parameters option on right mouse button for the layer.