Case 2 Tectonic load

 

In this exercise, after the initial elastic gravity initialization stage, an extra initialization stage will be added in order to increase lateral stresses via a tectonic load.

 

To perform this exercise copy the Case1 datafile as a template. Then copy and paste the Geostatic_control_data and Control_data data structures to add an extra control stage. A tectonic load is defined before the second stage Control_data. Then the geostatic control data structure keyword options for the second stage are modified as shown bellow.

 

Stage 2: Tectonic load

Data File

 

 

* Time_curve_data  NUM=1

! ---------------------------------

 Time_curve    IDM=11

 0.0000  0.2500  0.2625  0.2750  0.2875  0.3000  0.3125  0.3250              0.3375  0.3500  0.5000

 Load_factor   IDM=11

 0.0000  0.0000  0.0038  0.0152  0.0341  0.0603  0.0937  0.1340              0.1808  0.2340        1.0000

 

 

* Global_loads               NUM=1

! ---------------------------------

 Prescribed_displacement IDM=3 JDM=1

   -80 0 0

 Pres_displacement_geom_set   IDM=1

   "East_top"

 Pres_displacement_geom_ass   IDM=1

   1

 

   

* Load_case_control_data              

! ---------------------------------

 Loadcases                      IDM=1

  1

 Active_load_flags              IDM=1

  2

 

1A compressive load in the X direction is added to the top part of the eastern boundary (the boundary above the detachment). The load magnitude is defined to be 1% of the model length (80m).

 

2The load is ramped up gradually following a non-linear function (starts at low rate and then rate smoothly increases).

 

3The load is defined as being active in the Load_case_control_data (flag 2).

 

 

 

Stage 2: Geostatic Control and Control Data

Data File

 

 

* Geostatic_control_data

! ----------------------------------------

 Stress_constitutive_model            "Elastic"

 Stress_initialisation_type           "None"

 Contact_constitutive_model           "Elastic"

 

   

* Control_data

! ========================================

 Control_title           "Tectonic load"

 Solution_algorithm                    1  

 Maximum_number_time_steps       1000000

 Duration                           0.25

 Factor_critical_time_step           0.5

 Output_frequency_plotfile            -1

 Screen_message_frequency            500

 Output_frequency_restart             -1  

 

1Both constitutive model and contact model are kept elastic during this stage.

 

2The stresses from the previous stage will be kept by setting Stress_initialization_type to "None" (no stress initialization following the Geostatic_data input).

 

3Control_data is identical to the first stage (see Case1).

 

The data  and result files for the project are in directory: geost_002\Exercises\Case2