maria flor

Member • Jul 9, 2011

## CE Board Exam- Hydraulics and Geotech Review Problems

-A confined aquifer is shown. This aquifer has a source of recharge located as shown. The hydraulic conductivity of the aquifer is 40m/day with porosity of 25%. The piezometric (head) surface in the two observation wells 1250m apart are at elevation 65m and 60m, respectively from the common datum. The aquifer has an average thickness of 25m and an average width of 4km.

1. Determine the nearest value to the rate of flow of water through the aquifer, in cubic meters per day.

A. 14,000

C. 18,000

D. 15,000

2. Determine the nearest value to the seepage velocity in m/day.

A. 0.76

B. 0.42

C. 0.54

3. Determine the nearest value to the time of travel from the head of aquifer to a point 3.4km downstream, in days.

A. 4876

B. 6325

D. 5874

-A 4.2m thick layer of sand is underlain by a layer of clay. The water table is 2m below the ground (sand) surface. For sand, Gs = 2.65 and the average void ratio is 0.52. The sand above water table has a degree of saturation of 0.37. The saturated nit weight of the clay layer is 20.2 kN/m3.

1. Determine the unit weight of sand above water table in kN/m3

A. 17.86

B. 20.46

C. 10.65

2. Determine the total stress at a point 10m below the ground.

B. 123 kPa

C. 232 kPa

D. 167 kPa

3. Determine the effective stress at a point 10m below the ground.

A. 134.5 kPa

C. 156.9 kPa

D. 111.1 kPa

1. Determine the nearest value to the rate of flow of water through the aquifer, in cubic meters per day.

A. 14,000

**B. 16,000**C. 18,000

D. 15,000

2. Determine the nearest value to the seepage velocity in m/day.

A. 0.76

B. 0.42

C. 0.54

**D. 0.64**3. Determine the nearest value to the time of travel from the head of aquifer to a point 3.4km downstream, in days.

A. 4876

B. 6325

**C. 5313**D. 5874

-A 4.2m thick layer of sand is underlain by a layer of clay. The water table is 2m below the ground (sand) surface. For sand, Gs = 2.65 and the average void ratio is 0.52. The sand above water table has a degree of saturation of 0.37. The saturated nit weight of the clay layer is 20.2 kN/m3.

1. Determine the unit weight of sand above water table in kN/m3

A. 17.86

B. 20.46

C. 10.65

**D. 18.35**2. Determine the total stress at a point 10m below the ground.

**A. 199 kPa**B. 123 kPa

C. 232 kPa

D. 167 kPa

3. Determine the effective stress at a point 10m below the ground.

A. 134.5 kPa

**B. 120.4 kPa**C. 156.9 kPa

D. 111.1 kPa