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Loading
The following options are available in Swedge for applying loading to wedges to simulate de-stabilizing or stabilizing forces:
Critical load values can easily be determined with the Sensitivity Analysis option.
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Loading: Water Pressure
The effect of water pressure on the joint planes can have a great effect on wedge stability, decreasing the safety factor. Water pressure can be applied to the joint planes by selecting the Water Pressure option in the Input Data dialog.
Water Pressure option in Input Data dialog
 
The Water Pressure can be defined by specifying the water level in the slope, or by specifying the pressure on each joint plane. When Water Pressure is applied, this is indicated by blue arrows displayed normal to each joint plane, as shown in the following figure.
For more information see the Water Pressure topic in the Swedge help system.
Display of Water Pressure arrows (rear view of wedge)
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Loading: Seismic Force
Seismic Force can be applied to the wedge by selecting the Seismic checkbox in the Input Data dialog, and entering the seismic coefficient and direction.
Seismic option in Input Data dialog
 
The Seismic option in Swedge is a pseudo-static analysis in which the seismic coefficient is multiplied by the mass of the wedge and acceleration due to gravity to compute the additional body force on the wedge.
There are three options for specifying the direction of the Seismic force:
Line of Intersection - applies the Seismic Force in the direction (Trend
and Plunge) of the Line of Intersection of Joints 1 and 2
Horizontal & Intersection Trend - applies the Seismic Force horizontally,
but with the same Trend as the Line of Intersection of Joints 1 and 2
User Defined - allows you to define any direction (Trend and Plunge) for
the Seismic Force.
When Seismic Force is applied, this is represented by an arrow displayed at the base of the wedge, as shown in the following figure. The direction of the arrow corresponds to the direction of the seismic force.
Display of Seismic Force (yellow arrow)
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Loading: External Force
Loading (or support) can be represented as an External Force, with a given direction and magnitude. External forces are defined in the Input Data dialog. You can define one or more forces.
Two external forces defined in Input Data dialog
An External Force is displayed as an arrow applied to the wedge. In the following figure, two external forces have been applied. Depending on the direction of the force, the force arrow will either be displayed on the slope face or upper face of the wedge.
Two external forces applied to wedge
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Loading: Pressure
The Pressure option allows you to specify a distributed force which is applied to the slope face and / or the upper face of the wedge. The pressure is specified in terms of force per unit area, and may represent:
support pressure (for example, rock bolts applied to the slope face of
the wedge)
loading pressure (for example, a distributed load on the upper face of
the wedge)
The Pressure option is the easiest way to model the effect of pattern bolting or distributed loads, since the wedge face area is automatically accounted for.
Pressure dialog
When pressure is applied, the corresponding wedge face is shaded and an arrow is displayed as shown below.
Pressure applied to slope face (shading and arrow)
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Loading: Sensitivity Analysis
The Sensitivity Analysis option makes it easy to determine critical load values. Simply enter a range of values and from the sensitivity plot you can determine the value which corresponds to a specific factor of safety.
For example, in the following sensitivity plot, a seismic coefficient of approximately 0.2 corresponds to a critical safety factor = 1.
Seismic coefficient versus factor of safety
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