Introduction
Tunnelling components are currently being defined for the next IFC release 4x4. The following allows Catia users to anticipate the future implementation.
In 2023x GA the new components are defined to address both the space and element requirements of the IFC.
When to use which space component
Fundamentally the new notion of underground space is introduced, this is the underground equivalent to "Building"
Under this component the various types of spaces available can be divided into to types of use cases, a) running section (section courante) b) : localised structures (ouvrage singulier).
Tunnel running sections components are always bound by localised components, with the possible exception of the cut and cover tunnels.
Running sections (Typical sections)
| Use case | Example | Symbol |
|---|---|---|
Typical cross-section used along a certain length of tunnel, usually defined by the geological conditions or the type of excavation method. | ||
| Typical cross-section used along a certain length of an inclined adit or tunnel, usually defined by the geological conditions or the type of excavation method. The grade is sufficiently important to warrant specific construction methods which may impact the tunnel's geometry and/or work stages.. | ||
| Typical cross-section used along a length of shaft, usually defined by the geological conditions or the type of excavation method. The grade is near vertical and uses shaft excavation techniques. | ||
| Typical cross-section used along a length adit, which is differentiated from a tunnel by the smallness of the excavated section or the temporary nature of tunnel. Often used in hydropower works around the caverns used to house the turbines. The cross-section depend on the geological conditions, or the proximity of other underground structures, and the type of excavation method. The grade is from near horizontal to relatively steep. | ||
| Enlargement of an existing tunnel. This is usually the case when a first exploratory tunnel or ventilation gallery is excavated on the future tunnel's alignment. | ||
| Typical cross-section used along a certain length of cut and cover tunnel, usually defined by the depth of backfill soil and usually of rectangular cross-section. Near horizontal in alignment |
Localised structures
| Use case | Example | Symbol |
|---|---|---|
| Tunnel portal is the entrance point from the ground into the tunnel. It is the face from which the tunnel is excavated. | ||
| Intersection of a tunnel running section with another , smaller tunnel's running section.The intersection of two tunnels implies that the interconnection requires a specific design. | ||
| Intersection between two tunnel running sections with similar dimensions. this is a use case that is similar to the above, but with specific issues which necessitate particular phasing in the works | ||
Cross-passages is a special case of the connection component as, within a single component, two connection are modeled as well as the full length of the interconnecting tunnel. This is usually done when the two main tunnels are not too distant from one another. Can also be used between a tunnel and a shaft where the connection with tunnel and shaft as well as the cross-passage are modeled as a single entity. This component avoids using two interconnection components plus a typical section for the running section of the gallery when linking the two main tunnels/shafts in close proximity. This is important as the gallery's design is impacted by the tunnel and connection details (rock decompression, etc..). If the distance between main tunnels is important then it is better to model the gallery seperately from the main tunnel connections, as would be done when doing a 3D FEM model. | ||
| Gallery that is designed in whole, and not as a typical section along a certain length. For instance a gallery that is between a connection with a tunnel and a portal. The component may Include the connection with the tunnel or not. | ||
| Transition section are placed between tunnel running sections based on two differing cross-sections. | ||
| Localized widening in the tunnel's cross-section to cater for various safety equipment. These niches impact the design and construction methodology of the whole tunnel section not only at the niche's location but also for some distance either side of the niche, as such it included also a portion of the main tunnel's cross-section | ||
| Cavern geometry is of a given length, with usually many interconnections with adits. As such "typical cross-section approach is not appropriate. | ||
| Other underground spacial structures |
Legacy
The above new components aim to replace Full tunnel space, Tunnel section, other tunnel space.
Ring space is particular because it refers to both the ring and the space between the ring and the ground
Element components
| Use case | Example | Symbol |
|---|---|---|
| Excavation, inclusive of overbreak, used to calculate spoil volumes and to drive the phasing of the excavation works | ||
| Ground support (planar) such as shotcrete or injections in the case of ring segments. Rock bolts, steel sets, etc.. have their own components | ||
| Ring segment as used in TBM excavation methods, but not only (Jacobson method for instance). | ||
| Tunnel waterproofing membranes or sprayed | ||
| Tunnel final lining, usually poured in-situ or final shotcrete | ||
| Other elements of the tunnel's typical profile, such as invert backfill for instance in a TBM drive |
