Tunnel Axis Orientation

The Tunnel Axis Orientation is the Trend / Plunge of the excavation axis, looking "down" the axis of the excavation or tunnel.

The Tunnel Axis Orientation may be entered in:

Horizontal Excavations

For horizontal excavations the Plunge = 0, and remember that the Trend assumes that the viewer is "facing" the Opening Section cross-section, looking along the excavation axis.

Inclined or Vertical Excavations

For inclined (e.g. ramp) or vertical excavations, remember that the Trend must correspond to the Y-axis of the Opening Section as defined in the Opening Section view. For vertical excavations the Plunge = 90.

Tunnel Axis Plot

The Tunnel Axis Orientation can be optimized with respect to any analysis output variable, for example: maximum wedge volume, minimum factor of safety, minimum support pressure to achieve design factor of safety etc. This can be done with a single mouse click -- see the Tunnel Axis Plot topic for details.