Case 2 - 10% shortening at strain rate of 0.05/Ma
Contents
In this exercise a lower displacement rate for the tectonic event will be considered (strain rate of 0.05/Ma). This will be achieved by considering the same amount of shortening over a longer time period of 2.0Ma, however still targeting 100 flow steps for this duration, i.e. time step of 0.02. We will repeat the gradual time step reduction workflow adopted for the final sedimentation stage in Case 1 to transition to the tectonic stage time increment of 0.02. To this end, the usage of restart files will be employed to run the final deposition stage again and the new tectonic stage thereafter. There is no need to repeat any of the previous nine deposition stages.
To perform this exercise it is required:
1.To copy the "hm_005_Case1_stage_10.rst" generated after the ninth deposition from the previous example into a new folder.
2.Copy the restart datafile to the new folder and then modify it as shown below.
Data File |
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* Restart_Read_data ! --------------------------------- Restart_file_name "hm_005_Case1_stage_10.rst"
!--------------------------------------------------- ! Stage 11 Sedimentation #10 !---------------------------------------------------
* Sedimentation_data ! --------------------------------- Stratigraphy_unit_name "Layer10"
* Control_data ! --------------------------------- Control_title "Layer10" Solution_algorithm 4 Target_number_time_steps 200 Duration 4.0 Initial_time_increment 0.04 Maximum_time_increment 0.04 End_step_time_increment 0.02 Transient_time_step_growth 1.02 Screen_message_frequency 10 Output_time_plotfile 1.0 Output_frequency_plotfile -1 Output_frequency_restart -1
!--------------------------------------------------- ! Stage 12 Tectonic displacement !---------------------------------------------------
* Global_loads NUM=1 ! --------------------------------- Name "Displacement" Prescribed_displacement IDM=2 JDM=1 /Set 1/ -100.0 0.0 Pres_displacement_geom_set IDM=1 "East" Pres_displacement_geom_ass IDM=1 1
* Time_curve_data NUM=1 ! --------------------------------- Name "Displacement" Time_curve IDM=2 44.0 46.0 Load_factor IDM=2 0.0 1.0
* Load_case_control_data ! --------------------------------- Loadcases IDM=1 1 Active_load_flags IDM=1 2
* Control_data ! --------------------------------- Control_title "Compression" Solution_algorithm 4 Target_number_time_steps 1500 Duration 2.0 Initial_time_increment 0.02 Screen_message_frequency 10 Output_time_plotfile 0.4 Output_frequency_plotfile -1 Output_frequency_restart -1
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1Read the restart file written after the ninth sedimentation stage, i.e. "hm_005_Case1_stage_10.rst".
2Perform the simulation for the final (tenth) sedimentation stage with initial time increment of 0.04 transitioning gradually to time increment of 0.02 at the end of the stage.
3The time on the Time_curve_data is modified so that the displacement occurs between 44 and 46 Ma (0.1 strain/2 Ma = 0.05/Ma strain rate).
4Define the control data to perform 100 flow steps over the stage duration of 2.0Ma and 1500 mechanical steps per flow step, i.e.: a)Target_number_time_steps set to 1500 defines the target number of mechanical steps per flow step. b)Initial_time_increment set to 0.02 defines the flow step time increment, i.e. 100 flow steps over 2.0 Ma duration. |
The result files for the project are in directory: HM_005\Exercises\Case 2\Results. This directory also contains the excel file 00_hm_005_Case02.xlsx which contains ParaView plot over line results at time 44 Ma and 46 Ma as shown graphically below.
The effects of the tectonic event can be visualized below: - increase in overpressure, - decrease in porosity, - increase in Sxx' and Szz', decrease in Syy', - increase in deviatoric stress, increase in effective mean stress at depths above 2000 m and decrease in effective mean stress at depths below 2000m.
Parameters vs depth before and after the tectonic event
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