Liner Overview

In early versions of the Phase2 program, Liner support was used primarily to model tunnel liners such as sprayed on shotcrete or concrete. With each new version of the program, the capabilities of the Liner support model were expanded to include support types which are not necessarily liners, but which can be modeled using the same general procedures. So the term Liner support in Phase2 is multi-purpose and now covers a wide variety of geotechnical support types.

Liner support can now be used to model:

• Simple liners (e.g. a single layer of shotcrete)

• Reinforced Concrete

• Composite Liners (e.g. liners consisting of multiple layers of material)

• Pile walls (e.g. a structural beam element with a joint on both sides)

• Geosynthetic support such as geogrids and geotextiles

• Struts or other free-standing support elements

• Cable truss support used in coal mines

In all cases, the basic support properties of the liner are entered in the Define Liner Properties dialog. Other modeling differences are summarized below, see the links for further information.

Simple Liner

A simple liner represents a single layer of reinforcement which is applied to excavation or other boundaries. This would typically be used to represent a layer of shotcrete. For a simple liner, no joint interface is considered (i.e. the liner is fully bonded to the soil or rock).

• Liner properties are defined with the Define Liners option.

• A simple liner is added to a model with the Add Liner option.

Composite Liners

Composite Liners can be defined, which represent up to 4 different layers of material (e.g. shotcrete or concrete). The layers can be applied at different stages. A joint can be included between the first layer and the rock, or between any two layers of the composite liner.

• The support properties of each individual layer of a Composite Liner, are defined using the Define Liners option. Joint properties are defined with Define Joints.

• The overall properties of a Composite Liner (i.e. liner/joint/liner/... combination, and staging sequence) are defined with the Define Composite option.

• A Composite Liner is added to a model with the Add Liner option.

For more information see the Composite Liner Overview topic.

Piles

A structural support element such as a pile, which consists of a beam element with a joint on both sides, can be modeled with the Structural Interface option.

• Pile support properties are defined with the Define Liners option. Joint properties are defined with Define Joints.

• The overall properties of a pile (i.e. joint/liner/joint combination) are defined with the Define Structural Interface option.

• A Pile is added to the model with the Add Structural Interface option.

For more information see the Define Piles topic.

Note: a pile can also be modeled as a simple liner, if you do not wish to consider the interface (joint) properties.

Geosynthetics

Geosynthetic support such as geogrids or geotextiles, with a sliding interface on both sides, can be modeled with the Structural Interface option.

• Geosynthetic support properties are defined with the Define Liners option (set the Liner Type = Geosynthetic). Joint properties are defined with Define Joints.

• The overall properties of a geosynthetic (i.e. joint/liner/joint combination) are defined with the Define Structural Interface option.

• A Geosynthetic is added to the model with the Add Structural Interface option.

For more information see the Define Geosynthetics topic.

Note: a geosynthetic can also be modeled as a simple liner, if you do not wish to consider the interface (joint) properties.

Struts

Liners can be used to model support which crosses an excavated space, such as struts or similar support elements. However, in order to use this capability in Phase2, you must turn OFF the Automatic Liner Removal option. This allows you to define a liner which crosses an excavated space. See the Automatic Liner Removal topic for more information.

For a tutorial which illustrates the modeling of struts, see Tutorial 17 (Trench with Piles and Struts).

Cable Truss

The Cable Truss liner type allows you to model cable truss support systems.