YOUR HW MUST BE STAPLED YOU MUST USE A PENCIL (no pens)

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Esmond Nash
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1 Spring 2008 CIVE 462 HOMEWORK #1 1. Print out the syllabus. Read it. Write the grade percentages in the first page of your notes. 2. Go back to your 301 notes, internet, etc. and find the engineering definition of the following terms. Write down the definition and the SI units of each. (a) Stress (b) Pressure (c) Strain (d) Stiffness (e) Strength 3. Do the following problems 2.1, 2.3, 4.2, 4.3, 4.5, 4.21, 4.23 Second Edition 2.1, 2.4, 4.3, 4.5, 4.8, 4.29, Look at figure 4.15 (page 123) in the text. Which soil will have a higher stiffness: one with very angular particles or the other, with well rounded particles, why? Which one will have a higher strength? why? YOUR HW MUST BE STAPLED YOU MUST USE A PENCIL (no pens)

2 Spring 2008 CIVE 462 HOMEWORK #2 Please do the following problems (from the textbook) (read the remark below problem 5.6) Second Edition (read the remark below problem 5.7)

3 Spring 2008 CIVE 462 HOMEWORK #3 - Compaction Please do the following problems. 6.5 Second Edition

4 7kp25 ; 8fn27 Spring 2008 CIVE 462. HOMEWORK #4 Problems. 1. Do problem 7.2. A sketch may help you solve it faster. Do problem 7.6. Second Edition 2. Do problem 7.3. Remember, the pore pressure is the pressure head at the point in question times the unit weight of water. Do problem 7.7 Second Edition 3. Do problem 7.6. Note: disregard the piezometer readings and their space-apart distance. Use the practical method of determining the gradient like we discussed in class Do problem 7.14 Second Edition 4. Do problem 7.7, and also calculate the hydraulic conductivity of a clean coarse sand with D 10 = 2 mm and a clean sand with D 10 = 0.2 mm. Use Hazen s equation. Do problem 7.21 Second Edition 5. Water flows through a soil specimen with a flowrate Q = 1 cm 3 /sec. The soil has a k=10-2 cm/sec, and a void ratio e = The specimen diameter is 10 cm, and its length is 20 cm. Compute the Darcy velocity and the pore velocity. Which one is greater? Is this always the case? Briefly explain why 6. Do problem NOTE: use 4.25 km instead of 4.25 miles. Use 6 cm instead of 6 inches. Wherever it says ft, use meters. Express you answer in meters cubed per hour. Do problem 7.30 Second Edition Problems 7 and 8 in the following page

7kp25 ; 8fn27 7. Do the following computations using the seepage situation below (ignore the piezometer): a. Compute the total head at all equipotential lines. b. Compute the flowrate Q assuming that the concrete spillway is 1000 ft.

5 7kp25 ; 8fn27 7. Do the following computations using the seepage situation below (ignore the piezometer): a. Compute the total head at all equipotential lines. b. Compute the flowrate Q assuming that the concrete spillway is 1000 ft. long (into the page). The hydraulic conductivity k = 10-5 cm/sec. c. Plot the uplift pressure along the base of the structure USING EXCEL. 8. Do problem 8.8. Do problem 8.7. Second Edition

6 Spring 08 CIVE 462 HW #5 Go to the following website: Study all the material presented. You should be able to complete the three problems provided in the last webpage ( problems ), as this material will be included in test #2.

7 CIVE 462 Spring 2008 HW #6 Consolidation/strength There are 3 pages in this assignment. 1. Do problem Do problem Second Edition 2. Do problem Do problem Second Edition 3. Do problem MAKE SURE THAT YOU ANSWER WHY? Do problem Second Edition 4. A soil profile for a site is shown below (Figure #1). A sample from the clay layer was obtained (from point B) and taken to the lab for testing (the sample taken from point A was very disturbed and deemed unusable by the project engineer. The results for the specimen obtained from point B are: p = 195 kpa, e o = 1.0, C c = 0.29, C r = 0.06 In the site, the water table will be lowered as shown in (Figure #2) as part of an excavation project. Compute the ultimate settlement of the CLAY layer due to this. Use data from specimen B (given above) to calculate the ultimate consolidation settlement of the clay layer. Figure #1 BEFORE Figure #2 AFTER 8 m Sand dry =18 kn/m3 sat =20 kn/m3 8 m A 2 m Clay =19 kn/m3 11 m 11 m B 3.5 m 7 m Sand =21 kn/m3 7 m Sand dry =18 kn/m3 sat =20 kn/m3 Clay =19 kn/m3 Sand =21 kn/m3 A B 2 m 3.5 m Rock Rock

8 5. Do problem 12.4 (no plotting). Use the following values for unit weight: Do problem Second Edition _dry_sand = 121 lb/ft 3 _sat_sand = 123 lb/ft 3 _sat_clay = 124 lb/ft 3 Compute the effective stress at t = 1, 2, 4, 8, and 16 years after the placement of the fill. You do not have to plot anything. Please fill this table with the values you get of course show your work! Use the chart method discussed in class Fig 12.4 Notice that in this case we have single drainage. You must use only the top half of the chart in Figure 12.4, (which is obvious) For point F in Figure (after fill placement) Time after fill placement (yrs) u h u e u

9 6. Answer the following questions using the profile shown below (use the chart method discussed in class Fig 12.4): Proposed Fill, =20 kn/m 3 15 m 12 m 15 m 7 m Sand dry =19 kn/m 3 Clay sat =20 kn/m 3 Sand sat =21 kn/m 3 A 3 m A specimen was obtained from the site at location A. Lab testing of this specimen yielded the following parameters: Cr = 0.05 Cc = 0.25 eo = 1.3 k = 1x10-3 cm/sec p = 450 kpa c v = m 2 /day Rock (a) What is the value of the total pore water pressure at point A before the fill is placed? (b) What is the value of the total pore water pressure at point A at time = infinity? (c) What is the value of the excess pore water pressure at point A before the fill is placed? (d) What is the value of the excess pore water pressure at point A 5640 days after fill placement? (e) What is the value of the total pore water pressure at point A 5640 days after fill placement? (f) Compute the ultimate settlement of the clay layer due to the application of the fill. (g) Compute the settlement of the clay layer 5640 days after the application of the fill. (h) What is the degree of consolidation of the clay layer 5640 days after the application of the fill? (i) How much time has to go by (after fill placement) for the degree of consolidation to be 90%? (j) If the cohesion intercept for the clay layer is c = 25 kpa and the friction angle is = 20 degrees, what is the strength of the soil at point A on the horizontal plane: a. Before the fill is placed? b days after the application of the fill? c. At time = infinity? (k) At t = 0, what is the strength of the soil at point A on a plane inclined 30 degrees clockwise from the horizontal? YOU MUST DRAW THE MOHR CIRCLE.

10 CIVE 462 HW #7 1. A clean sand was tested in the lab with a triaxial device, in drained conditions. The cell pressure during the test was 30 kpa. The test data is shown below. Note: the values of shown include both the piston stress and the cell pressure. Determine the effective peak and effective critical state friction angles and the effective cohesion. Was the sand dense or loose before testing? ' (kpa) Strain (%) 2. An undisturbed, saturated clay specimen was placed inside a direct shear box with cross-sectional area = 200 cm 2, loaded vertically with 100kPa, and immediately sheared. The test data is shown below. Determine the critical state undrained shear strength of the clay (do not forget units). Was the clay overconsolidated or normally consolidated prior to shearing? T (kn) (mm)

11 3. Consider the profile shown below. 12 m 15 m Proposed fill =19 kn/m 3 Clay =20 kn/m 3 K = 0.45 A 3 m 70 o 7 m Clean Sand =21 kn/m 3 K = 0.5, = 35 deg. B 1 m Rock (a) If the cohesion intercept for the clay layer is c = 25 kpa and the friction angle is = 20 degrees, what is the strength of the soil at point A on the horizontal plane: a. Before the fill is placed? b. After consolidation has ended. (b) Before the fill is placed, what is the strength of the soil at point A on a plane inclined 30 degrees clockwise from the horizontal? DRAW THE MOHR CIRCLE.

1.91. kg m s. Solving for m s yields m s kg. Now we can use the fundamental definition of water content to get the mass of water. m w = 0.

1.91. kg m s. Solving for m s yields m s kg. Now we can use the fundamental definition of water content to get the mass of water. m w = 0. 1 CE 46 - Homework #1 Solutions Problem #.1. Problem - A contractor will want to charge you more for coring through that "soft rock layer". However, your expertise tells you that that layer is not rock