Principles of Foundation Engineering (MindTap Course List)
9th Edition
ISBN: 9781337705028
Author: Braja M. Das, Nagaratnam Sivakugan
Publisher: Cengage Learning
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Chapter 2, Problem 2.8P
To determine
Find the amount of water flowing into the ditch per day.
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2.8
A 500 m long levee made of compacted clay impounds
water in a reservoir as shown in Figure P2.8. There is a 1 m
thick (measured in the direction perpendicular to the seam)
sand seam continuing along the entire length of the levee, at
10° inclination to the horizontal, which connects the reser-
voir and the ditch. The hydraulic conductivity of the sand is
2.6 × 10-³ cm/s. Determine the volume of water that flows
into the ditch every day.
Given the following:
H1 = 1.5 m
H2 = 3.0 m
H3 = 2.0 m
K1 = 0.001 cm/sec
K2 = 0.032 cm/sec
K3 = 0.000041 cm/sec
1. Find the effective average permeability of the
deposit in the horizontal direction. (in cm/s)
2. Find the effective average permeability of the
deposit in the vertical direction. (in cm/s)
3. What is the ratio of the equivalent hydraulic
conductivity?
1. (30 pts) The soil profile shown below consists of 10 meters of sandy silt overlying gravel.
The pore water pressure at the top surface of the silty sand is zero and can be assumed to
remain zero.
a) Calculate the level to which water would rise in a piezometer tube inserted into the top
of the gravel if the silty sand is just stable? Use submerged unit weights and seepage forces
to arrive at your answer (do not calculate total stresses and pore water pressures). Express
your answer as an elevation, e.g. "Elev. 130". (Note: Elevations are in meters) (10 pts)
b) Using the piezometric elevation calculated in part (a), calculate the pore water pressure
at the bottom of the silty sand if the silty sand is just stable (10 pts).
c) Calculate the total stress at the base of the silty sand and show that it is equal to the pore
water pressure calculated in part (b) (10 pts)
Elev. 120 m.
Elev. 110 m.
Sandy Silt (saturated)
Void ratio, e = 0.68
G = 2.65
Gravel
Chapter 2 Solutions
Principles of Foundation Engineering (MindTap Course List)
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- A sand has Gs = 2.66. Calculate the hydraulic gradient that will cause boiling for e = 0.35, 0.45, 0.55, 0.7, and 0.8.arrow_forwardFrom the figure shown, H₁ = 0.60, H₂ = 0.90 m. and h = 0.45 m. The sand has a saturated unit weight of 18.65 KN/m³. Hydraulic conductivity of sand K= 0.12 cm/sec. If the cross sectional area of tank = 0.46 m², determine the rate of upward seepage of water in liters /sec. h=0.45m T H₂=0.60 m H₂-0.90 m Direction of flow H₂O Sand ILGS G valve openarrow_forwardbe the hydraulic conductivity at 20°C? Ans. 1.0 x 10 cm/sec 4. For a normally consolidated clay, the following values are given. k(cm/sec) 0.45 x 10 e 0.78 1.1 0.88 x 10 Estimate k at a void ratio of 0.97 6.0089 107arrow_forward
- be the hydraulic conductivity at 20 Docs A20 pe 4. For a normally consolidated clay, the following values are given. k (cm/sec) 0.45 x 106 0.78 1.1 0.88 x 106 Estimate k at a void ratio of 0.97arrow_forwardFrom the figure shown, the thickness of permeable layer is 1.1m making an angle of 14 degrees with the horizontal. K= 4.87x10^-12 cm/sec. If the vertical thickness depth of the aquifer at point of the first piezometer (left) is 1.5m and the other point at second piezometer is 1.1m, determine the area of flow. h=1.4 m Direction impervious layer of seepage 3 m 14 1.1 m impervious layer 14 -36 m-arrow_forward2. Consider the stratified soil deposit shown in the figure. There are four layers, 3m thick each, and kH1=2x10³, kH2=1x105, kµ3=2x104, kH4=1x10³in cm/sec. Determine the equivalent coefficient of permeability in the horizontal direction and the total flow in cm3/sec per cm width. H Direction of flowarrow_forward
- From the figure shown, the void ratio of the sand is 0.55 with a specific gravity of 2.68. The cross-sectional area of the tank is 0.5 sq.m and hydraulic conductivity of sand = 0.1 cm/s. a. What is the rate of upward seepage in cu.m/hour? b.Determine the critical hydraulic gradient for zero effective stress. c. Determine the value of h (head loss) to cause boiling. NEED ASAP. THANK YOU.arrow_forward7.10 The hydraulic conductivity of a sand at a void ratio of 0.5 is 0.022 cm/sec. Estimate its hydraulic conductivity at a void ratio of 0.7. Use Eq. (7.31). 7.18 A layered soil is shown in Figure 7.31. Estimate the ratio of equivalent hydraulic conductivity, kmeq/kvieg)- 1.5 m 1 m 1.5 m |k = 2 × 10-³ em/sec (top layer) | k = 2 × 10-4 cm/sec | k = 10-4 cm/sec | k = 3 × 10-4 cm/sec (bottom layer) Figure 7.31 -arrow_forwardFrom the figure shown, the thickness of permeable layer is 1.1m making an angle of 14 degrees with the horizontal. K= 4.87x10^-12 cm/sec. If the vertical thickness depth of the aquifer at point of the first piezometer (left) is 1.5m and the other point at second piezometer is 1.1m, determine the seepage velocity. h=1.4 m Direction of seepage impervious layer 3 m 14 1.1 m impervious layer 14 -36 m-arrow_forward
- Water flows in the upward direction in a tank through 2.5 m thick sand layer as shown in the figure. The void ratio and specific gravity of sand are 0.58 and 2.7, respectively. The sand is fully saturated. Unit weight of water is 10 kN/m³. Outward flow 1.2 m 1m water Sand 2.5m •A 1m Filter media Inward flow > The effective stress (in kPa, round off to two decimal places) at point A, located 1 m above the base of tank, is alicearrow_forward2. A confined aquifer is recharged by a continuous supply of water from the certain source. The average thickness of the aquifer was determined to be 25 m and the average width is 4 km. The hydraulic conductivity of the aquifer was obtained at 40 m/day and its void ratio is 0.3333. The piezometer heads in two wells 1.325 km apart are 65 meters and 60 meters from a common reference datum. Determine the rate of flow in cubic meters per day. Determine: •compute the rate of flow through the aquifer in m3/day •compute the seepage velocity in m/day •compute the time of travel from the head of the aquifer to a point 8 km downstream in daysarrow_forward(c) A dam shown in Figure Q1 (c) retains 6m of water. A sheet pile wall on the upstreamside (which is to reduce seepage under the dam) penetrates 4m into a 10m thick of siltysand stratum. Below the silty sand is a thick deposit of clay. Assume that the silty sandis homogeneous and isotropic. (i) Calculate q in cm/s.(ii) Analyze the pore water pressure distribution on the front of the sheet pile (atevery 2m @ at points A, F and G). Given the Nd of points A, F and G are 0.5,1.5 and 3.0 respectively.(iii) Analyze the pore water pressure distribution at the base of the dam. (at every5m @ at points A, B, C, D and E). Given the Nd of points A, B, C, D and E are5.6, 6.7, 8.0, 10.0, 13.0 respectively.(iv) Determine the uplift force under the dam.(v) Calculate the factor of safety against piping. Given Lmin = 0.85m.arrow_forward
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