# Applying Shotcrete

To include Shotcrete support in an **SWedge** analysis:

- Select the Shotcrete option in the Support menu.
- 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).
- 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 SWedg
*e*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.