PLAXIS version 8

Tutorial manual Dynamics manual

subject of presentation :

Presented By : Hamed Zarei

The names of God

Geometry of a tunnel

Material properties

Boundary conditions

Mesh generation

Initial conditions

Calculations

Viewing output results

The creation of a geometry model is based on the input of points and lines. This is

done by means of a mouse pointer in the draw area.

Tunnel designer with current tunnel model

The tunnel considered has a diameter of 5.3 m

Space between tunnels is 12m

creation of a horseshoe-shaped tunnel

Click on the Standard fixities button to apply the appropriate boundary

conditions. In addition to the standard displacement fixities

The creation of material data sets is generally done after the input

of boundary conditions. Before the mesh is generated, all material

data sets should have been defined and all clusters and structures

must have an appropriate data set assigned to them.

After the input of boundary conditions, the material properties of

the Rock clusters and other geometry objects are entered in data

sets.

Material properties of Rock in the tunnel project

𝜇E

( 𝐾𝑁𝑚2)

𝜑)Degree(

C( 𝐾𝑁

𝑚2)

γ( 𝐾𝑁

𝑚3)

0/235 x1054370030

𝜇𝑊

( 𝐾𝑁 𝑚 𝑚

)

𝐸𝐼( 𝐾𝑁 𝑚2

𝑚)

𝐸𝐴( 𝐾𝑁

𝑚)

0/22/317501/728 x 105

Material properties of the Shotcrete

The properties for those Shotcrete are listed in Table

∅(𝑚𝑚)

𝐸𝐴( 𝐾𝑁

𝑚)

251/2x 106

Material properties of the Rock bolt

In this example the 15-node element is used as the basic

element type.

The global coarseness parameter can remain at its default value (Fine).

It can be expected that stress concentrations occur around the tunnel.

Therefore the mesh should be refined in these areas.

The first calculation phase is used to excavate the right tunnel and activate

Shotcrete

Select a Plastic calculation using Staged construction

The second calculation phase is a

plastic calculation, Staged

construction.

The second calculation phase is

used to excavate the left tunnel

and activate Shotcrete

Start the calculations

Select some characteristic points for load-

displacement curves

Standard earthquake boundaries are used at the bottom and at

the right hand boundary to avoid spurious reflections

The earthquake is modelled by imposing a prescribed

displacement at the bottom boundary.

Therefore the input value of the horizontal prescribed

displacements is set to 0.01 m. The vertical component of the

prescribed displacement is kept zero

(ux=0.01m and uy=0.00m).

Change the Rayleigh damping parameters

α and β to 0.001 and 0.01 respectively

Select Dynamic analysis for the calculation type in the

General tab sheet.

Set the Time interval to 0.5 sec in the loading input box

In this phase, a vertical harmonic load, with a frequency of

10 Hz and amplitude of 50 kN/m2