Design Standard

RocTunnel3 currently supports the Eurocode 7 (EC7) and British Standard (BS) 8006 design codes. The loading and resistance factors stipulated in the codes are automatically applied to the forces and material properties during the analysis of the factor of safety.

Specifying a Design Standard

To specify a design standard for analysis:

1. Select Analysis >Project Settings to open the Project Settings dialog.
2. Navigate to the Design Standard tab.
3. Here you can select from a list of supported design standards along with their associated combinations of partial factors. The partial factors can be viewed by clicking View Partial Factors button.
4. You can also define your own list of partial factors by clicking the Add button, and then selecting an existing standard as a base. These lists can also be exported and imported between RocTunnel3 models (*.sldf).

What are Partial Factors?

In the Eurocode 7 and British Standard, factors must be applied to the loading and resistance components of the block stability analysis. These factors serve to amplify the actions inducing the block failure and/or reduce the capacity of resisting components. Different factors are applied to different components of the analysis – hence the term “partial” is used to describe them.

Depending on the standard, the factors can be multiplicative or divisive. If you are adding your own factors, be sure to review the standard that you are basing the set of factors from.

In some standards, separate factors are required depending on whether a particular force in the analysis is Favourable or Unfavourable with regards to preventing the block from sliding.

A sample list of partial factors from the BS 8006: 2010 is provided below.

Specifying Applied Loads

If a design standard as been specified in Project Settings, then the interface for adding Loads to the model will have an option to specify whether an applied load is Variable or Permanent (Live and Dead, respectively). Depending on the selection and, if applicable, whether the load is Favourable or Unfavourable to prevent sliding of the block, RocTunnel3 will automatically apply the appropriate partial factor(s) during the analysis.

Specifying Support Capacity

When specifying support capacities in RocTunnel3, there are options in two different locations to apply reduction factors to the strengths.

• The Design Standards interface, as previously discussed.
• In the Define Bolt Properties dialog, under the Design Factors tab (Support > Define Bolt Properties)

References

Bond, A.J., Schuppener, B., Scarpelli, G. and Orr, T.L.L. (2013). Eurocode 7: Geotechnical Design Worked Examples. [workshop presentation] Luxembourg: Publications Office of the European Union, pp. 16-31.