Tutorial 1: Bearing capacity calculation for a pile group

Example 12.22 - Principles of Foundation Engineering. Braja Das.

The cross section of a 3 x 4 pile group in layered saturated clay is shown in the figure. The piles have a square cross section of 356 mm × 356 mm and a center-to-center spacing of 889 mm.

Determine the allowable bearing capacity of the pile group using a safety factor of 4. Note that the water table is at the ground surface.

1. Whether you are in My workspace or in a project’s work location, go to the App.
2. On the left panel, locate the Models list and click the New model button to open the menu. Then, select Deep Foundation and choose the Pile group template.
   

1. On the right panel, locate the Type of analysis section and make sure the Pile group switch is set to on.

1. In the Foundation soil section, expand Layer 1 by clicking on it. Then, select Cohesive as the analysis condition,and input the values for Undrained cohesion, Unit weight, Saturated unit weight, Thickness and choose a Color for the layer. Repeat for Layer 2.
2. Set the Water table level to zero.

1. In the Structure section, select the pile cross-section as Square, and then input the Side length and Pile lenght.

1. Then, in the Pile group section, enter the number of piles in the X and Y directions, as well as the spacing between them.
   

For this example, the pile load value is irrelevant. Leave the default value.

1. Once all parameters are set, verify that the structure appears as expected.
2. Click the icon at the top of the right panel to run the model.
3. The Results tab will be enabled and will display the analysis results.
   

Below is a summary of key variables and their expected versus obtained values.

• Das, B. M., & Sivakugan, N. (2018). Principles of Foundation Engineering.