1 you are working for urs on a building project

Question

1. You are working for urs on a building project in dearborn, michigan. You are responsible for the design of the building foundations.

3. Clay given the following consolidation test results (see fig. 3) on a 1 in. Thick representative sample of the clay in a fixed ring consolidometer.

Fig. 3 consolidation test results at a vertical effective stress of 1.5 tsf.

determine the coefficient of consolidation (c )

3a. What is the drainage distance in the test:____________

3b. What is the dimensionless time factor tv:_____________

3c. What is the time to reach 50% consolidation in the lab test:

1. 10.6 minutes 2. 5.3 minutes

3. 2.65 minutes 4. none of the above

3d. Calculate the coefficient of consolidation

4. For the soil and foundation conditions in fig. 1, determine the time required to reach 75% consolidation in the clay given the consolidation test results in fig. 3.

4a. The thickness of the clay layer in fig. 1 is:___________________

4b. Determine the excess pore water pressure at the top of the clay layer caused by the building stress

4c. Determine the excess pore water pressure at the bottom of the clay layer caused by the building stress

4d. Determine the ratio of the excess pore pressure at the top and bottom of the clay layer α:

4e. What is the dimensionless time factor tv at 75%

consolidation:_____________

source:____________

4f. Calculate the time to reach 75% consolidation

5a. Calculate the vertical effective stress in element "a" prior to construction

5b. Calculate the horizontal effective stress in element "a" prior to construction

5c. If the net bearing pressure is 3.92 k/ft², calculate the vertical effective stress in element "a" the end of building construction. Use fig 9.7 in text.

5d. What is the horizontal effective stress at element "a" at the end of building is construction?

5e. Construct the before and after mohr circles of state of stress at element "a" on a mohr diagram. Use a separate piece of paper.

5f. Determine the effective normal stress and the effective shear stress on the potential failure plane in element "a" in fig.3.

5g. If the cohesion in the sand is 0 and the effective friction angle in the sand is 35^o, is the strength of the sand exceeded at element a? Show your analysis on your constructed mohr diagram.