Flac Simple Tutorial (not the Demo)1. Go to the saved location of Flac 7.0(or 6.0) and run the program.

2. Type C for continue, this will bring up the graphic screen.

3. Close the model options screen; close the project file screen.

4. Click File and then click Exit GIIC. This will exit the graphic screen and return you to the command screen.

5a. On the command screen, type in the command new and then press enter. This will start the process of creating a new model.

5b. Type C to continue, as you are only using the demo version

Now from this step you can enter the commands directly into flac OR you can create a .txt file (notepad). Using a .txt file allows you to change/alter your model and rerun the flac program without reentering all of the commands. I recommend the .txt method.

If you want to enter the commands directly into flac follow the “Simple Flac Tutorial” at step 6. Otherwise follow the steps below for a .txt file method.

6. Open Notepad. Next, we will need to set the boundaries of our model. It will be a grid that is 5 by 5 units. Type in grid 5,5 and press enter.

7. Next, we will set the material properties of the zones. Type Model Mohr enter, prop bulk=1e8 shear=.3e8 fric=35 enter, prop dens=1000 coh=1e10 ten=1e10 enter. Remember to leave spaces where they are required or the command will not be recognized.

8. Next, we will set boundaries for the model as if it were resting as it would in the Earth. Without the boundaries on the sides and bottom, the model would simply fall infinitely. Type fix y j=1 enter, for the bottom fix x i=1 enter, fix x i=6 enter, for the sides.

9. Next, we will set the gravity as it would be in the real world. Type set grav=9.81 enter. 10. Next, we set the number of time steps that we wish the model to go through. This will allow

for gravity to develop and the stresses and strains to develop. Type his nstep=5 enter, his ydis i=2 j=6 enter.

11. Now we will solve the model by allowing the model to come to equilibrium. Type Solve and press enter.

12. Next, we will excavate part of our model. First type prop coh=0 enter, set large enter, init xdis=0 ydis=0 enter, model null i=3 j=3,5 enter. For better explanation of these commands, please see the demoflac file on blackboard.

13. Next, we will advance the model through time. Type Step 100 and press enter

14. Next we type Plot plastic boundary to see a graphic representation of the present state of the individual zones.

15. Next we will install three beams in the excavation. This is done by typing struct beam begin grid 3,4 end grid 4,4 seg=2 and press enter, struct beam begin grid 3,5 end grid 4,5 seg=2 and press enter, struct beam begin grid 3,6 end grid 4,6 seg=2 and press enter, struct prop 1 e=200e9 i 2.3e-5 area 4.8e-3 and press enter,

16. At any time from this point further we can advance the model further through time by entering Step (and any number) and press enter. You can even increase the number of steps you use to any number, into the thousands if you want. With the construction of the beams the model is now stable and can advance through time without failure. Without the beams, the model would eventually fail. You can see this as you set up the model without the beams and then advance it through time.

17. Next we need to tell the program what information to display, type plot grid beam white and press enter

18. When you are finished you should have a .txt file that looks something similar to:

19. Save this file in the upper level of a directory where it is easy to find (i.e. first level of a jump drive). Such as e:1.1x.txt is the location where I have chosen to save this. I put it in the e: drive at the first level. The deeper you bury it in sub folders the harder it is to find it.

You are now ready to run the flac analysis. Follow steps 1-5 above. Then skip to step 20.

20. At the flac: prompt type call {then the address to your saved .txt file.} (mine is call e:1.1x.txt) and press enter.

21. Type C to continue as you are only using the demonstration mode.

22. The program will run and briefly flash results (very brief). To view your results type plot grid beam iwhite dis red and press enter

23. Your results should be similar to figure below. Get a screen shot of this.

24. Now go back to your .txt file and change something (rock properties or geometry or remove the beams or change beam properties). Be sure to select realistic properties, but select the extreme min or max of that property (i.e. change the modulus of the beams, or the moment of inertia or the size, but reference why you have chosen those values. You need to explain what you have changed and why these values are reasonable). Save this as a separate .txt file (i.e. I used 1.4.txt instead of 1.1x.txt). Rerun your flac analysis starting on step 20 above using your modified model. Use the step command to step your file until failure occurs (see step 16 above). Provide a screen shot of your failure and describe what you did to make it fail (i.e. what you changed).

For this failure I changed the beam geometry to (explain what you changed), the beam properties (I changed the modulus from ? to ?, this is reasonable because…), and then time stepped it ahead 700 time steps. You can see that the trench is beginning to collapse.

You can omit the beams, change the beams from steel to some other material (change properties accordingly and reference where you found those values), change the rock properties (change properties accordingly and reference where you found those values), change trench geometry, just about anything you want to do. Play around with the parameters. You will need to cite where you got any new material parameters.