Concept explainers
(a)
State whether the statement "seepage velocity is always greater than the discharge velocity" is true or false.
(a)
Answer to Problem 6.1P
The given statement is
Explanation of Solution
Express the derived equation to relay seepage velocity
Here, q is the flow rate, v is the discharge velocity, A is the gross cross sectional area,
Seepage velocity is based upon the void space of the soil and simultaneously the discharge velocity is based upon the gross sectional area of the soil. Therefore, this directly means that the seepage velocity is greater than the discharge velocity.
Thus, the given statement is
(b)
State whether the statement "hydraulic conductivity of a sandy soil is greater than that of a clayey soil" is true or false.
(b)
Answer to Problem 6.1P
The given statement is
Explanation of Solution
The hydraulic conductivity (k) for clayey soils varies for different types and the k value for Silty clay is
The hydraulic conductivity (k) for sandy soils varies from
Based on the above values, hydraulic conductivity (k) for sandy soil is greater than the clayey soil.
Thus, the given statement is
(c)
State whether the statement “hydraulic conductivity is same for water and oil in a porous medium” is true or false.
(c)
Answer to Problem 6.1P
The given statement is
Explanation of Solution
For each time, the hydraulic conductivity contains the unit of length and this represent that there is a fluid flow which is a property of porous medium. However, the viscous fluid like oil moves slowly through sand when compared to water. From the above comparison, it means that the flow of water and oil differs in the hydraulic conductivity of the porous medium.
Hence, the given statement is
(d)
State whether the statement “pressure head is proportional to the pore water pressure” is true or false.
(d)
Answer to Problem 6.1P
The given statement is
Explanation of Solution
Write the pressure head equation
Here, u is the pore water pressure,
The above equation shows that the pressure head
Hence, the given statement is
(d)
State whether the statement “magnitude of pressure head depends on the selected datum” is true or false.
(d)
Answer to Problem 6.1P
The given statement is
Explanation of Solution
Write the pressure head equation
From the above equation, it is clear that the pressure head magnitude depends upon the datum plane. However, the pressure head magnitude does not depend upon the selected datum.
Hence, the given statement is
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Chapter 6 Solutions
Fundamentals of Geotechnical Engineering (MindTap Course List)
- A confined aquifer bed with a varying thickness as shown in the following figure. The aquifer hydraulic conductivity is 15 m/day. The piezometric heads at x=0 is 15.5m and at x=2000m, head is 22.1m. Determine the flow rate per unit width assuming the flow in theaquifer is essentially horizontal.arrow_forward1. Calculate the equivalent hydraulic conductivity for the soil profile shown in figure 2. An excavation is proposed for a square area near the bend of a river, as shown in figure. It is expected that the flow of water into the excavation will come through the silt layer. Pumping test reveal an average horizontal hydraulic conductivity of 2 x 10 -5 cm/s in the silt layer. The excavation has to be kept dry. Determine the flow (qs) into the excavation.arrow_forwardCALCULATION USING DARCY'S LAW An aquifer system is formed by two horizontal layers. Two piezometers were installed for monitoring, the distance between them is 885m. The upper layer (A) has a thickness of 39m and K = 1.3 x 10-5 m/s and the lower layer (B) has a thickness of 25m and K = 2.7 x 10-6 m/s. THE hydraulic load in the PZA is 60m and in the PZB it is 40m. Calculate the flow and the transmissivity of each layer.arrow_forward
- At n = 0.45, the hydraulic conductivity of the sand is 0.010 cm/sec. Determine the hydraulic conductivity at n = 0.50.arrow_forward11. A channel runs almost parallel to a river as shown in the figure. The water level in the river has an elevation of 36 m. and the elevation of the channel is 33 m. The river and channel are 600 m apart and a previous formation of the average thickness of 9 m and hydraulic conductivity of 0.80 m/hr joints them together. Compute the hydraulic gradient Compute the rate of seepage flow from the river to the channel per meter width in liters per day. If the seepage velocity is 0.048 m/day, compute the void ratio of the previous medium.arrow_forward29. Soil in a field has three layers. Each has a thickness of 3m, 4m, and 3m, from top layer to bottom layer. The hydraulic conductivity of each layer is 0.0043cm/s, 0.0072cm/s, and 0.0018cm/s, respectively. Calculate the effective horizontal hydraulic conductivity.arrow_forward
- Estimate the ratio of equivalent hydraulic conductivityarrow_forwardFor the two-dimensional flow system shown below (units in meters):Compute the total flow rate under the Dam. X = 4, Y = 8. Note 1: Point A is located in the middle point of the equipotential lines. Point B is located in the middle point of the flow lines.Note 2: Assume e=0.8 (void ratio) and k=10^-3 cm/s (coeff. of permeability).Note 3: Datum is located at the bottom level of the water (right side of Dam).Note 4: Remember, the figure is drawn to scale. So, use the value of 2X+Y to estimate any dimension that you consider necessary.arrow_forward/ 2.8 If the specific weight of a sludge can be expressed as gamma(y) = 10200 + 105h, determine the pressure in N/m^2 at a depth of 4.5 m below the surface. Gamma(y) is in N/m^3 , and h in m below surfacearrow_forward
- In a field testing, the hydraulic gradient between two peizometers is 1.11, the area of flow is 4.08 m2 and the hydraulic conductivity of the aquifer material is 0.94 m/day, calculate the discharge in m3/day. Note that discharge cannot be negativearrow_forwardA 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.arrow_forward1. 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 18 m and the average width is 8 km. The hydraulic conductivity of the aquifer was obtained at 60 m/day and its void ratio is 0.1586. The piezometer heads in two wells 2,145m apart are 128 meters and 188 meters from a common reference datum. 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
- Fundamentals of Geotechnical Engineering (MindTap...Civil EngineeringISBN:9781305635180Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage Learning