HA Method Design Example (English)

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Transcript of HA Method Design Example (English)

  • Tensar International Corporation

    Software Training Course

    TensarSoil HA Method Design Example

    Section to be analyzed

    System Specific Information SierraSlope Retention System WWF facing with BX wrap Vegetated with turf reinforcement mats

    Soil Properties Reinforced and retained fill Sandy fill: = 32, c = 0 psf, = 120 pcf, Reinforced and retained fill 125 pcf bulk weight below water level Foundation Soil Assume Competent Maximum fill particle size = 1/4 in.

    Loading Conditions Traffic live load = 250 psf Earthquake loading = NA Groundwater: See cross-section for location

    Geogrid Design Parameters Structure design life = 75 yrs Soil-geogrid interaction factors: Cds = 0.8 and Ci = 0.8

  • HA68/94 Slope Design Example

    Step 1: Set up a new design case 1. Select Region 2. Uncheck structure face angle and seismic loading 3. Select public or private project owner 4. Select design method (HA68/94 only) 5. Select/make a new file

  • Step 1: Set up a new case (Cont)

    You will see now see the main screen above

  • Step 2: Define slope geometry

    1. Input slope geometry 2. Input geogrid embedment length

  • Step 3: Select slope system type

    1. Click on the circled button to select the type of wall system for design

  • 1. Select SierraSlope WWF vertical 2. Review slope face angle, wall height, define

    geogrid spacing, geogrid percent coverage. Revise as needed. Hit Set when finished.

    Step 3: Select slope system type (Cont)

  • Step 4: Set surcharge loading

    1. Input the location and load for surcharge. Select Live or Dead load. Hit Set when finished.

  • Step 5: Set groundwater location

    1. Click on Enter water pressure data icon to set the groundwater location

    2. Input groundwater location in front and within reinforced fill. Hit Set when finished.

    Water within fill

  • Step 6: Input soil parameters

    1. HA method is developed based on constant volume friction angle as described earlier.

  • Step 6: Input soil parameters (Cont)

    2. The program is modified to include the use of peak friction angle with user defined FS. Select Assessing fill shear strength in cases where constant volume values are not available.

    3. Input the peak soil strength parameters and appropriate FS for design. Hit the Set button on the right to set the input values

    4. Input the unit weight and select the maximum particle size for reinforced fill

    5. Hit the Set button on the lower right when finished

  • Step 7: Review and set geogrid design parameters

    1. Input the structure design life and hit Set 2. Review the maximum particle size and geogrid

    class. Hit OK when finished. 3. Select Review design parameters to review the

    geogrid reduction factors if needed.

  • Step 7: Review and set geogrid design parameters (Cont)

    4. Click on Non-standard design parameters to change installation damage and durability reduction factors if needed. Hit OK when finished.

  • Step 8: Set soil-geogrid interaction coefficient

    1. Input the coefficient of direct sliding, Cds 2. Input the pullout coefficient of interactions. Click

    OK when finished.

  • Step 9: Input cost data

    1. Input the cost of geogrid and hit OK when finished.

  • Step 10: Perform design and stability analysis

    1. The set up is now complete and ready to run analysis 2. Select Keep grid lengths equal and hit Proceed

  • Step 10: Perform design and stability analysis (Cont)

    3. The first click on Proceed activate the Tob mechanism to find the minimum geogrid length to satisfy sliding at base

  • Step 10: Perform design and stability analysis (Cont)

    4. The second click on Proceed indicates the geogrid embedment length from Tob mechanism. The program is ready to proceed with Tmax mechanism to find the number of geogrid layers with weakest geogrid strength and minimum geogrid length for pullout

  • Step 10: Perform design and stability analysis (Cont)

    5. The third click on Proceed indicates the geogrid minimum number of geogrid layers and length to satisfy Tmax and pullout

  • Step 10: Perform design and stability analysis (Cont)

    6. You will see this screen with after the third click on Proceed. It listed the minimum dimensions to meet Tob and Tmax mechanism

    7. Extend geogrid length or revise the angle of back of block as needed. Click Proceed to proceed to next step.

  • Step 10: Perform design and stability analysis (Cont)

    8. The spacing curve screen will appear as follow 9. Adjust/modify the geogrid layout, percent coverage or

    coefficient of pullout interaction for each individual geogrid layer if needed.

    10. The plotted points should fall on the left of the spacing curve for each geogrid type to satisfy geogrid strength requirements

  • Step 10: Perform design and stability analysis (Cont)

    11. Once completed the geogrid layout and design, click on Proceed to run two-part wedge for compound and surficial stability analysis

  • Step 10: Perform design and stability analysis (Cont)

    12. Click on Proceed to activate the two-part wedge for compound and surficial stability analysis

  • Step 10: Perform design and stability analysis (Cont)

    13. The program will indicate if the design is satisfactory. Hit Start again if revise the design if needed

  • Step 11: Export to TensarSlope for global stability analysis