Tutorial 5: Two walls connected with strut and base slab

1. Tutorial 5: Two walls connected with strut and base slab Deep Excavation LLC DeepEX 2015 – Advanced course 1

2. INTRODUCTION DeepEX is a software program for braced excavations in soils with 2D limit-equilibrium and non-linear analysis methods, and structural verification of all elements (with AISC, ASD, Eurocodes). It offers the ability to analyze walls with multiple braces (tiebacks) in multilayered soils. The non-linear analysis considers elastoplastic behavior for the whole soil-wall-support system. The program also offers the ability to perform traditional limit-equilibrium analyses. The graphical interface is completely interactive and the input is simplified to a great extend. The program utilizes archives of wall types, structural and soil materials, ground anchors etc. The analysis can be performed in either an utlimate state or at a service state (allowable design, LRFD, or Eurocode 7 design approach methods). The program offers the ability to automatically set all critical settings according to the desired design methodology. Corso Paratie, Milano 30 settembre 2009 DeepEX 2015 – Advanced course 2

3. Program layout File menu (click) General input tabs Design section list (right click) Model space (left or right click on any item) Project tree view 3D Model (Frames) Mouse is over item Units Wall selection View and other Model stages (right click options similar to excel) Command prompt (enter coordinates) Instruction box Press to perform calculations. DeepEX 2015 – Advanced course

4. Enter basic project information 1. Select this button 2. Define the project name etc. 3. Press OK DeepEX 2015 – Advanced course

5. Move model elevations 1. Select this button 2. Set new reference elevation to 100 ft 3. Check All boreholes (this moves all soil layers) 4. Press OK

6. 1. Add a 2nd wall2. Double click on right wall3. Change dimensions3.1 Change xwall= 60ftDepth L= 45ft

7. Define basic model limits (top, bottom, left, right) 1. Select this button 2. Set Top= 130ft Bottom= 40ft Left= -60ft Right= 120ft 3. Press OK DeepEX 2015 – Advanced course

8. Modify soil types (database of soils) 1. Select this button. Or Expand the Soils Tree and Double click on F Options: Right click or press Delete Boring with F soil Note: In DeepEX you can use any soil type in more than one borehole. For example the F soil can be used in boring 1 or boring 2 etc. You can use any Boring on any design section. Thus changing any property of the F soil will affect all the excavation Design Sections where F is used!

9. Soil type data form Test data for estimating soil properties Short soil name, description and color. Available soil types Soil type & initial clay behavior Density Strength Add new, copy, delete, paste soil DeepEX 2015 – Advanced course

10. Soil type continued Soil properties: General Soil name: F (this appears in the boring) Description: Detailed soil description. Soil type: Sand gt= 125 kcf : Total unit weight gdry= 120 kcf : Dry unit weight (above water table) c‘= 0 : Effective cohesion F’= 30 degrees : Effective friction angle v= 0.35 Poisson’s ratio Kx = Horizontal permeability Kz = Vertical permeability Parameters only for clays Su = Undrained shear strength Fcv= Constant volume shearing angle Fpeak= Peak shearing angle DeepEX 2015 – Advanced course

11. Soil properties (Resistance and Elastic) Enter elasticity values as shown before. Click on > buttons for more options. KoNC = At rest lateral earth pressure coefficient for normally consolidated state. DeepEX 2015 – Advanced course

12. Soil S1 Soil properties: Change S1 A. General Soil name: S1 (this appears in the boring) Description: Sand Detailed soil description. Soil type: Sand gt=125 pcf : Total unit weight gdry= 120 pcf: Dry unit c‘ 0: Effective cohesion F’ = 36 degrees : Effective friction angle V = 0.35 Poisson’s ratio C. Elasto-plastic E = 500 ksf rEur = 3 D. Bond Ultimate bond = 30 psi Press OK

13. Edit Borings (soil layers) To edit the soil layers double click on the model boring. The borings can also be edited from: a) Edit Borings Button. Or from the: Tree View – Stratigraphy – boreholes Double click here (or right click) with the mouse. DeepEX 2015 – Advanced course

14. Enter Soil Layers To edit the soil layers click on the blue button and enter the top of layer elevation. For this example type 90 here: Then select soil type S1 here: Press OK DeepEX 2015 – Advanced course

15. DeepEX 2015 – Advanced course

16. Double click on wall DeepEX 2015 – Advanced course

17. 2. Select edit section data, to change wall properties 1. Change wall depth to 45ft Number of nodes controls the divisions along the wall in a limit-equilibrium analysis. (Suggested 200 min, or set so that small intervals (0.25 ft) are generated) DeepEX 2015 – Advanced course

18. Change wall section AZ 19 sheet pile 1. Change wall type 2. Select AZ-19 section 3. Select A50 steel (fy= 50 ksi) 4. Select OK DeepEX 2015 – Advanced course

19. Wall using AZ-19 wall section Select OK DeepEX 2015 – Advanced course

20. Add a new stage (Model Tab) Or right click (to add a stage, similar to Excel) DeepEX 2015 – Advanced course

21. Stage 1 change center El. 90 Stage 1 DeepEX 2015 – Advanced course

22. Add Stage 2: Add a strut at El. +92 Right click and add stage 2 DeepEX 2015 – Advanced course

23. You can also drag the surface with your mouse

24. Select tool to add a strut Note: After selecting the “Draw ground anchor button” the program tells you to select/enter the 1st tieback point at the wall (x z) DeepEX 2015 – Advanced course

25. Add tieback with mouse 1. Select 1st point on left wall (we will modify the coordinates later 2. Select 2nd point on right wall

26. Edit strut section • Typing PP24x0.375 will generate a pipe 24” OD x 0.375” thick wall • Typing PM600x12 will generate a pipe 600 mm OD x 12mm wall

27. Add 3rd stage and excavate to El. +80

28. Changing the water table • Double click or drag the water table • Change the water elevations in the general tab • Click on the water table button • The drop down offers other possibilities for drawing user defined water profiles.

29. Add stage 4: Draw in a slab between the two walls

30. Drawn model with slab

31. Edit slab properties • Create 3ft thick slab • Elevation refers to slab center • Specify +80 + 3ft/2 = El. +81.5 • Change spacing to 1ft • Edit slab section to make a 3ft slab • Include slab weight in vertical stress • Select “Use user defined unbraced lengths” and use 10ft

32. Edit slab section to 3ft • Slab thickness d= 36inches • Slab width b= 12” • Change reinforcement bars to #9 • Ctop and Cbot are clearances to center of bars

33. Completed model with 3ft slab • Green points show that slab is supported at “rigid points” • Slab is not really on ground. • Slab weight is added to vertical soil stresses. NOTE: EXCAVATION IS NOT YET SEALED

34. Change water levels and seal excavation • Change water elevations to El. +90 • Go to analysis tab, and apply seal excavation Purple line shows that excavation is sealed (lined). Dashed water table inside excavation shows the water potential and that the excavation is dry within.

35. Reviewing vertical soil stresses and water pressures: • Important that total vertical stress is greater than water pressures • Must maintain positive vertical effective stress • Program does not consider contribution from wall side resistance and dead weight.

36. Review forces on slab • Double click on slab • Water pressure at bottom of slab: 0.62 ksf (rounded) • Used FS STR= 1.6 shows the safety factor used to determine the design capacities • This was defined in Design tab