Reference no: EM132645047

Question 1. Go back to your CPT HW analysis plots. Look particularly at the plots of u2 and un. FR and Φ Notice how these parameters behave at z = approximately 20m, z = approximately 21.5m, and z = approximately 23.5m. Thew spikes above 1k,, the FR spikes up, and the Φ spikes down. These are very thin layers of fine grained soil that found themselves layered in a large coarse grained sod deposit over the history of the site Such thin layers or -seams- were probably deposited during draughts.

Classify the soil that composes each of these seams using the classification chart (no need for a graph-chart combo, simply select a representative FR and a representative qi for each seam (do this by eye. looking at the plots: do not pick exact values from the data)

Question 2. Go to PART Ill of your Reader and study the Induced Stresses section

Question 3. Calculate the geostatic vertical effective stress (σ' v0)at a point located at a depth of 0.5 meters in a dry sand layer. Note: this problem (and the rest of this HW) is not related to HW 3 problems.

Question 4. Revisit what you just read about induced stresses and calculate the induced stress (Δσz) at a point located at a depth of 0.5 meters in a dry sand, below the corner of a square 1.5m x 1.5m area loaded with q = 120 kPa.

Question 5. Go to PART Ill of your Reader and study items 1. 2. 3. and 4 of the Shallow Foundations section

Question 6. Let's say that the corner of the area described in problem 4 above is aligned with the point of problem 3 above. Draw the area as an unembedded footing that rests on the profile and denote the point in the drawing. Keep the profile dry. Now, calculate the net vertical stress at the point after the footing is loaded (assume that the footing has no weight) The answer is simply rf + sat. i.e.. the sum of the terms that you calculated in problem 3 and problem 4. respectively Make sure that you understand this.

Question 7. Calculate the induced stress below the center of a circular. unembedded. weightless footing with diameter = 1.2m. loaded with P = 100 kN (draw it). at the following depths.
a. At z = 0(Δσ_z= q in this case)
b. At z = B
c At z = 2B

Question 8. Go to PART III section of your Reader and continue reading the Shallow Foundations section. Study al the way up to (but not including) the Criterion 2 (SETTLEMENT) section. If there are any examples, make sure that you work them out by hand on the side, so that you truly understand them

Question 9. Watch the following two videos and take notes on your Reader

Question 10. Solve the following problem A structural engineer has hired you to design square concrete unembedded footings for a building. based only on capacity. Each footing will hold an axial load of 180 kN. Your technicians have conducted lab tests on specimens sampled from the site, and they report the following profile. a 2-meter thick sand layer over a 7-meter thick gravel layer (the gravel layer lies over rock). The lab report reveals that the friction angle of the sand is 33 degrees, and that of the gravel is 39 degrees. Determine the size of one of the footings, in meters. such that the short term factor of safety against a capacity failure is between 3 and 3.3. Show all your work. organized, and circle your answer

Question 11. Solve the following problem A structural engineer has hired you to design square concrete unembedded footings for a buichng, based only on capacity Each footing will hold an axial load of 120 kN. Your technicians have conducted lab tests on specimens sampled from the site. and they report the following profile a 2-meter thick clay layer over a 7-meter dick clayey silt layer (the clayey silt layer lies over rock) The lab report reveals that the clay has a friction angle of 38 degrees and an undrained strength of 55 kPa, and that the clayey silt has a friction angle of 40 degrees and an undrained strength of 72 kPa. Determine the size of one of the footings, in meters. such that the critical (smallest) factor of safety against a capacity failure es between 3 and 3.3 Show all your work, organized and circle your answer.