This tutorial demonstrates non-linear boundary element analysis of a pile group. It shows you how to:
Specify a non-linear analysis
Introduce a rigid layer into the calculations
Produce a load-displacement graph for the pile cap
Print the results of your calculations
The worked example involves the analysis of a group of 4 piles installed in stiff clay overlying rock.
The ground conditions at the site comprise 35m of stiff clay (Young's modulus 75 + 10z MPa vertically and half that horizontally, where z is the depth below the top of the layer; Poisson's ratio 0.5) overlying a rigid layer of rock.
A non-linear soil model will be used for the clay, which has a unit weight of 19.8 kN/m3, undrained strength of 75 + 10z kPa, and adhesion factor of 0.5.
The water table is at the ground surface.
The piles will be installed on a 2 x 2 grid, at 3m spacing (centre-to-centre) along the edge of the grid. Each pile is 20m long, 1m in diameter, with a free-standing length of 0.5m and Young's modulus of 30 GPa (both axially and laterally). This is the same pile group as was used in Step 2 of Tutorial 1.
You are interested in the displacements and rotation of the pile cap under a combined vertical load of 20 MN, horizontal load of 2 MN, and moment of 3 MNm. The loads will be applied at the centre of the pile cap.
Hyperbolic curve-fitting constants of 0.5 (for the shaft), 0.99 (for the base), and 0.9 (for lateral response) should be used.
Two analyses will be run, one without any limit on the mobilized shaft stresses and one with a limit of 100 kPa.
This tutorial is written for users of the Professional, Enterprise, and Trial Editions of Repute 2 only. Users of the Standard Edition should look at Tutorials 1-3.
In Step 1, you will use the Project Wizard to enter project information and create a scenario to represent the design situation to be analysed.
In Step 2, you will use the Pile Group Wizard to create a 2 x 2 pile group and specify the piles’ properties.
In Step 3, you will create a stiff clay and specify its properties.
In Step 4, you will create a layer and borehole to hold the stiff clay.
In Step 5, you will create a force, moment, and combination of actions (to combine the force and moment).
In Step 6, you will create the calculation that you want Repute to perform.
In Step 7, you will perform the calculation.
In Step 8, you will export results to a Microsoft Excel spreadsheet.
In Step 9, you will close and (optionally) save the project.
If Repute is not already running, double-click on the Repute icon on Windows’ Desktop to start the program. Once the splash screen has disappeared, Repute displays its Welcome page.
If you have an existing project open, click Close on the program’s Application menu. (You will be prompted to save your work if you have not already done so.)
Now you are ready to start the tutorial.
Step 1 - create the project