CA3687 Soil Mechanics

Assignment #2 Submission Deadline and Location: 13:00, 17 February 2015, B6302 or in class before lecture 6. Note: late submission will be subjected to score deduction. Follow up the Example Question 3 in the lecture of Topic 3 Soil Hydraulics: (a) calculate the vertical effective stress at Point P, which is located 15 m below ground surface, as shown in Figure a. The saturated unit weights of the earth dam and underlaid soils are both 20 kN/m3, (b) if a water cutoff curtain is installed in the middle of the earth dam and underlaid soils to completely cut off the water flow, as shown in Figure b, what is the vertical effective stress at Point P? (c) compare the difference of the vertical effective stress at Point P for cases a & b.

Figure a: Case a

Figure b: Case b

k=10-5 m/s

15 m

h = 15m

h = 12m h = 9m h = 6mh = 3m

h = 0

P5m

Datum 15 m sat = 20 kN/m3

sat = 20 kN/m3

k=10-5 m/s

15 m

P5m

Water Cutoff Curtain

15 m sat = 20 kN/m3

sat = 20 kN/m3k=10-5 m/s

15 m15 m

P5m

Water Cutoff Curtain

15 m sat = 20 kN/m3

sat = 20 kN/m3