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# Applying Shotcrete

To include Shotcrete support in an SWedge analysis:

1. Select the Shotcrete option in the Support menu.
2. In the Shotcrete dialog, select the check box, and enter the Thickness and Shear Strength of the shotcrete (see below for information about estimating shotcrete shear strength).
3. Select OK to re-compute the analysis.
All views of the current document will be updated with the latest results, including the effect of the shotcrete support.
NOTE: You can use the Apply button to re-compute the analysis without closing the dialog.

NOTE: Shotcrete is only applied to the slope face of the model. When you select OK or Apply in the Shotcrete dialog, you will notice that the slope face is shaded gray, to indicate the presence of shotcrete. Shotcrete is NOT applied to the upper slope of the model.

## How Shotcrete is Implemented in SWedge

Shotcrete is implemented in an SWedge analysis as follows:

• The maximum force which the shotcrete can exert on the wedge, is obtained by adding the trace lengths of Joint 1 and Joint 2 on the slope face, and multiplying by the shotcrete thickness and shear strength.

EXAMPLE: If the trace length of Joint 1 on the slope face = 10 meters, and the trace length of Joint 2 on the slope face = 12 meters, and shotcrete thickness = 0.1 m and shear strength = 100 tonnes / m2, then the shotcrete force used in the analysis = ( 10 + 12 ) * 0.1 * 100 = 220 tonnes.

• The DIRECTION of this force is NORMAL to the slope face, and directed INTO the slope.
• As with all other forces in SWedge (e.g. bolts, external, seismic), this force is applied through the centroid of the wedge.
• The shotcrete force is included as a PASSIVE force in the safety factor calculation. See the How Bolts are Implemented in SWedge topic, for a discussion of how ACTIVE and PASSIVE forces are defined in SWedge.

NOTE: The shotcrete force used in the analysis, and the trace lengths of Joint 1 and Joint 2 on the slope face, can be found in the Info Viewer listing.

## Estimating Shotcrete Shear Strength

To estimate the value of shotcrete shear strength, there are a variety of different codes that relate concrete compressive strength to shear strength. The Canadian CSA simplified standard is shear strength(MPa) = where f'c is the 28 day compressive strength in MPa. For example, given 35MPa unreinforced shotcrete, the shear strength is approximately 1.2 MPa (120 tonnes/m2). ACI and Eurocode are similar.