Tutorial Two (1)

Tutorial 2 Over-pass design Tutorial Two page CIVL2016 Civil & Substructure

In Tutorial 2, you will designing the tied-earth embankment at the start of the overpass at:  O’Connell Street for the Kingswood campus light rail  James Ruse Drive for the Parramatta (Rydalmere) campus light rail You will also be discussing the background theory, which you will need to include in Submission Two. Part 1. Compaction operations The fill for the embankment must be compacted to 95% of maximum dry density from the Standard Proctor test. Proctor densities You will have to calculate the dry density of each Standard Proctor test that you performed in Practical Two. Moisture content of each sample: 1. The weight of the Moist soil ( m 4 ) [grams] is the difference between the Dish-Moist soil ( m 2 ) and the Empty dish ( m 1 ): 2. The weight of the Dry soil ( m 5 ) [grams] is the difference between the Dish-Dry soil ( m 3 ) and the Empty dish ( m 1 ): 3. The Moisture ( m 6 ) [grams] is the difference between the Moist soil ( m 4 ) and Dry soil ( m 5 ): 4. The Moisture Content ( m %) is the division of the Moisture ( m 6 ) [grams] by the Dry soil ( m 5 ) [grams]. It is expressed as a percentage. 5. Complete Table 1 on the page 4 in pen. Dry density of each sample: 6. The moist weight of compacted soil ( w 4 ) in the Proctor mould is the difference between Mould + Compacted soil ( w 2 ) and the empty Mould ( w 1 ): 7. The dry weight of compacted soil ( w 5 ) is obtained from the moist weight, when you adjust for the moisture content: Tutorial Two page

Sample 1 Sample 2 Sample 3 Sample 4 Empty dish ( m 1 ) Dish-Moist soil ( m 2 ) Dish-Dry soil ( m 3 ) Moist soil ( m 4 ) Dry soil ( m 5 ) Moisture ( m 6 ) Moisture Content ( m %) Table 1 Sample moisture contents % ; ; ; Sample 1 Sample 2 Sample 3 Sample 4 Empty mould ( w 1 ) Mould + Moist compacted soil ( w 2 ) Moist compacted soil ( w 4 ) Dry compacted soil ( w 5 ) Dry density (  d ) Table 2 Dry densities [ kg/m 3 ] ; ; 0% 5% 10% 15% 20% 25% 30% 0 500 1000 1500 2000 2500 Moisture content Dry density [kg/m3] Figure 1 Dry density versus Moisture content Tutorial Two page

Spoil volume You must estimate the amount of loose spoil, that is needed for the overpass embankment. You will need to estimate the volume of soil which must be shifted from the excavation pit. Embankment Volume From the embankment drawings on the vUWS site, calculate the volume of the embankment in m 3 . The shape is irregular, so you will need to consult your tutor to work out the volume. Volume = WxHxL / 2 3.5m x 5.7m x 114m = 2274.3 2274.3 / 2 = 1137.2 (m3) Compaction factor The moist weight of loose soil [Sample 1] ( w 6 ) in the Proctor mould is the difference between Mould + Loose soil ( w 3 ) and the empty Mould ( w 1 ): W6 = 5.055 – 3.898 = 1.157 Dry weight of loose soil ( w 7 ) [Sample 1] is obtained by factoring with the moisture content (Sample 1): W7 = 1.157/ (1 +17/100) = 0.988 The dry weight of an optimum compacted sample ( w 8 ) is the product of 95% maximum density and the mould volume ( V = 9.44  10  4 m 3 ) : 0.95 x 1849.5 x V = 1.659 Tutorial Two page

Part 2. Granulometric analysis The weights from the Sieve Analysis in Practical Two are used for granulometric analysis of the test soil. You will be constructing both frequency and cumulative frequency ( % passing ) grading curves. Granulometric analysis 1. Transfer the sieve/pan+soil fraction weight ( w 1 ) and sieve weight ( w 2 ) from Practical Two to Table 3. 2. The Soil fraction weight ( w 3 ) is the difference between the sieve/pan+fraction weight and the sieve weight. 3. For each sieve, find the cumulative weight ( w 4 ) of soil by adding the weight of all fractions above. For example, the cumulative weight for No. 40 sieve is the weights for No. 8 sieve, No. 16 sieve, No. 30 sieve and No. 40 sieve. 4. The cumulative weight at the bottom pan is the total weight ( w T ) of the soil sample. 5. Divide the soil fraction weight ( w 3 ) by the total weight ( w T ) to generate the Soil fraction %. 6. Plot the Soil fraction percentages on Figure 2 below. 7. The Percentage retained is the division of the cumulative weight ( w 4 ) by the total weight ( w T ) , expressed as a percentage. 8. The Percentage passing is the opposite of Percentage retained: 9. Plot the Percentage passing on Figure 3 below. 10. Classify the test soil as coarse-grained or fine-grained: Coarse grained soils (Gravel and Sand) : less than 50% passing the No.200 (75 microns) sieve. Fine grained soils (Silt and Clay) : more than 50% passing the No.200 (75 microns) sieve. 11. Draw a freehand line through the Percentage passing data points. 12. Extrapolate the freehand line into the clay zone (to 0.001 mm or 1 micron) of Figure 3. 13. Scan pages 9 and 10 with your scanner or smart phone and insert the images in the Submission Two file. Tutorial Two page

Discussion c. Based on the classification of the test soil (coarse-grained/fine grained), nominate an appropriate compacter (smooth roller, sheepsfoot roller, etc.) for the embankment. Explain why you have chosen this type of compacter. d. Referring to Figure 2, you will be asked to improve the Grading characteristics of the test soil in the Submission Two file. e. You should discuss the problems of Extrapolating the grading curve into the clay zone with your tutor. There is a question in Submission Two that relates to this issue. f. The hydrometer test is based on Stokes Law . Investigate what factors affect the test on the internet, so that you can discuss the test in Submission Two. Tutorial Two page

Figure 2 Soil fraction percentages Figure 3 % Passing (Based on the % passing No. 200 sieve): Test Soil Classification = 3% (0.05 – 0.1 mm) Tutorial Two page

Part 3. Pavement strength The pressures from Practical Two are used to derive the CBR of tamped road-base. This data is used to determine the pavement thickness for tamped road-base. a. Calculate the CBR of the tamped road-base: b. Using Figure 4, determine the thickness of the tamped road-base pavement. Report the thickness in inches and millimetres. [ 25.4 mm  1 inch ] The design load is based on the U.S. Standard Light Rail Vehicle (see the Project Brief) . Total weight of vehicle with a crush load of 219 students = 52.3 tonnes or 115,280 lbs Wheel load (12 wheels per vehicle) = 4.36 tonnes or 9,600 lbs. Figure 4 Pavement thickness based on CBR (from www.facebook.com) Tutorial Two page

Part 4. Tied-earth retaining wall Sand density 1. For the density measurement, the weight of sand ( w 3 ) is the difference between the jar + sand weight ( w 2 ) [ kg ] and jar weight ( w 1 ) [ kg ] : 2. Calculate the sand density  s [ kg / m 3 ] . The volume V is 0.002m 3 (2 litres): 3. The unit weight  s [ kN/m 3 ] is related to the density: 4. The maximum overburden pressure  V [ kN/m 2 ] depends on the depth of fill D [m] : Earth pressure 5. The maximum earth pressure  H [ kN/m 2 ] is derived from the formula below: Note: The formula uses non-standard units to avoid confusion: Kilograms for the Pull P and millimetres for the Depth D . The maximum earth pressure  H is in the standard units of kN/m 2 . 6. The active earth pressure coefficient K a is the division of the earth pressure  H by the overburden pressure  V : 7. Using the data from Practical Two, complete Table 5 on page 14. 8. Scan Page 14 and insert in Submission Two. Tutorial Two page

Sand density Weight of sand Sand density Unit weight Active earth pressure coefficient Depth of Fill D Spring pull P Overburden pressure  V Earth pressure  H Active earth pressure coefficient K a [m] [kg] [ kN/m 2 ] [ kN/m 2 ] 0.30 0.35 0.40 0.45 0.50 Tutorial Two page = = =

Therefore, the light rail vehicle weight-force F lrv [ kN ] is derived from the product of the mass and the acceleration due to gravity (Take g as 10 m / s 2 ): 15. The light rail vehicle “footprint” A lry [ m 2 ] is the product of the vehicle width w lry (2.70m) and vehicle length l lry (21.64m): 16. The light rail vehicle vertical pressure  V,lrv [ kN/m 2 ] is the division of the light rail vehicle weight-force by its footprint: 17. The light rail vehicle horizontal pressure  H,lrv [ kN/m 2 ] is derived by factoring the light rail vehicle vertical pressure with the active earth pressure coefficient K a from step 6: Note that the superimposed pressure of the light rail vehicle is constant down the retaining wall. 18. The superimposed force F S [ kN ] on the lowest panel is calculated by multiplying the light rail vehicle horizontal pressure by the area A p of the panel ( 1.5m  1.5m = ) 2.25m 2 : 19. The total force F T [ kN ] on the lowest panel is the sum of the earth force F E and the superimposed force F S : 20. Referring to Figure 5, each steel rod F r [ kN ] must resist 1/6 th of the total force on the lowest panel: 21. In Building Science, you investigated the strength of materials. Using a permissible tensile stress f t of 150 MPa, calculate the cross-sectional area A r [mm 2 ] of each rod: 22. The required diameter d r of each rod is determined from the cross-sectional area: 23. Your calculations are done on pages 18 and 19. 24. Scan page 18 and page 19 with your smart phone or scanner. 25. Insert the scans into the Submission Two file. Discussion Tutorial Two page

f. From Module 8 (Retaining walls), explain why the earth pressure varies down the retaining wall, but the superimposed pressure does not vary , in the Submission Two file. g. Not all earth ties look like the steel mesh in Figure 5. Using the internet, research the different materials and cross-sections , that are used for earth ties for the Submission Two file. Use the keywords “mechanically stabilized retained earth”. h. For the embankment backfill, we assumed that material was the same as the active earth coefficient experiment in Practical Two. But clearly, we can tell from the granulometric analysis that the filling material is not a pure sand. Discuss with your tutor what effect this will have on the horizontal pressures on the retaining wall. Tutorial Two page

Light rail vehicle horizontal pressure Superimposed force Total force Steel rod force Cross-sectional area Required diameter Tutorial Two page