354 Final Exam Tutorial Topics

1. 353 review Consolidation Settlement (differential) Weight volume relationships Excess Pore pressure Effective/total stress Soil Strength Peak ultimate and residual t vs s and Mohr Coulomb Undrained vs drained Skempton’s A & B Loading and unloading Slopes Wedges and circular failures Mitchell charts (Ru) Simple derivations Bearing Capacity Terzaghi BC equation Rafts and footings Undrained and drained Settlement: elastic - consol Rocks, and N values Eccentricity Retaining Walls Earth pressures Rankine and Coulomb Factors of safety 354 Final Exam Tutorial Topics

2. Assumptions Vertical wall No vertical wall friction Failure planes @… Active Passive Deviate from Ko ** Active state soils push wall back Wedge is steeper than passive case Retaining Walls - Rankine

3. Rankine • Inclined deviates by: therefore However must still project by horizontal vertical

4. Rankine Pa • First term is soil pressure • Second term removes cohesion • Third term decreases cohesion to account for tension cracks

5. Pa acts at H/3 unless…

6. Example Answer Pa=117.5 Ka=1=0.333 Ka2=0.271 gc=25 d=16 Solve for sliding and Pa

7. Cohesion • What do you do when it is given • Can you trust it • Should it be there • Water is bad, can appear even in free-draining materials. Freezing? Uplift pressure?

8. According to C.F.M.: Two times the strain required for Ka is needed for full development of Kp @ Ka use 0.5 Kp Active vs Passive

9. Passive Aggressive

10. Slopes and Sliding • Slopes was a big section, but we didn’t have time to quiz you on a lot of it because of time constraints, but on an exam there is lots of time…. • Sliding blocks • Wedges • Bishops long hand • Mitchell charts • Free body diagrams

11. Wedgies Force balance You need to be able to understand the force systems from a first principles standpoint driving resisting Weight Water? Friction Cohesion Water?

12. Produces a factor of safety on a given slip circle No inter-slice forces No inter-slice shear Factor of safety for all slices is the same Assumes soil is a rigid plastic Simplified analysis but generally good for Fs>1.2 The circle with the the lowest Fs is the critical circle When the slope angle exceeds 53 degrees the critical circle will pass through the toe Must analyze on a slice by slice basis Bishop

13. Bishop Can you use this method on a wedge? What is angle a? Why does factor of safety appear twice? Is a drawn slip circle necessarily the lowest factor of safety circle? Where is ground surface?

14. Crap, don’t I need a bad ass table for this question Yes you do

15. Design charts solved for lowest factor of safety circle Three charts Ru=0.0, 0.3, and 0.6 Calc and use average Ru for slope and linear interpolate factor of safety between charts Remember using it backwards? Mitchell Charts Use To get Fs Ru 0 0.3

16. What about water at the toe Excavated slopes? To dewater or not to dewater that is the question Rapid drawdown Tension cracks and slopes Not out of the question There are even allowances on Mitchell charts for this Excavated slopes and stress path Slippery slopes

17. Footings, I got your footing right here buddy qa qf smax Take note of the omission of gD. Oversight, I think not. Assumptions? What is the physical meaning of each term?

18. Don’t forget about inclined loading Settlement Immediate drained Immediate undrained Consolidation settlement Layer model with m1m0 Stress distributions and settlement Fadum is Dr. Knight’s Favourite Could also use table from text if provided Don’t forget RQD but don’t obsess either N values re: qf Have I ever told you I hate footings

19. Like I need to talk to you about stress. Critical depth = 2B What about Fadum with a point of interest outside of the footing I see another stress distribution approximation for point loadds

20. Eccentricity! Doesn’t that have something to do with Liberace • Use qf from bearing capacity and it terns out that using B’ and L’ in the shape factors is more work than it is worth • If e>B/6 then must use B’ and L’ in qmax & qmin • What about strip footings and retaining walls?

21. M-C Failure Envelope Test 1 Failure Circle Sample will fail at intersection with envelope tfailure (2) t’ tfailure (1) Test 2 Failure Circle c’ s1(2) s3(1) s1(3) s1(Failure) s1(1) s1(2) s1(1) s1(3) s1(Failure) s3(2) s’n NOTE: all stresses are effective Soil Strength Each test is performed at a set void ratio

22. Developed “A” parameter for indication of the denseness of a sample Develpoed “B” for a measure of satuation Skempton What about negative values of Af

23. Soil Strength

24. Soil Strength Stress Path of Sample sinf’ = tana’ (s1 - s3)/2 = t Radius of Circle 3 a’ 2 t t = d' + S tan a' 1 S d = c' cos f' tan y = sin f' d s s = (s1' + s3')/2 Centre of Circle

26. t vs s space the final frontier

27. T & S is that anything like S&M? • Things to note • Ko line, how do you get it • Loading 1:1 to the right • Unloading 1:1 to the left • Time rate of dissipation of pwp • Stress path line • Better or worse than M-C?

28. Pore pressure is the difference Effective the what the soil “feels” Can effective exceed total? What does Drained mean. What are the implications of undrained? Bearing capacity and slopes Effective vs Total and Drained vs Undrained

29. Spring analogy Time rate of consolidation Differential settlement Excess pwp OCR Consolidation

30. Weight and Volume • Redo the buoyancy question from your first assignment. • Dry density • Saturation • Void ratio • Water content

31. Bearing capacity Raft or footing Fs against load, against settlement Inclined load, eccentric load Two layer settlement Retaining walls Rankine Two layer Inclined Passive resistance Water Jojo’s Network

32. Stress Calc and plot stress paths Convert M-C data to t&s Peak vs ultimate f and c Dilatency Slopes Be prepared for a slice analysis Draw force diagrams Water effects Excavations Jojo’s Network

33. Redo the buoyancy question from your first assignment. Dry density Saturation Void ratio Water content Theory Assumptions Coulomb Af Total vs Effective Consolidation Mitchell vs Bishop Psychic Friends Network

34. In central America several ancient structures that rivaled the pyramids existed. Some were destroyed some remain How could you use geotech to determine if you were on the site of a large temple that had been destroyed The panama government has a site that may be of significance to archeologists, but a mining company wants access to subsurface ore deposits. If mining begins al archeological evidence will be destroyed. Can you help determine if the site is important? Thought game

35. Assumptions • What would you look for? • Calculations?