Principles of Geotechnical Engineering (MindTap Course List)
9th Edition
ISBN: 9781305970939
Author: Braja M. Das, Khaled Sobhan
Publisher: Cengage Learning
expand_more
expand_more
format_list_bulleted
Concept explainers
Textbook Question
Chapter 7, Problem 7.22P
Refer to Figure 7.24. The following data were collected during the field permeability measurement of a confined aquifer using a pumping test. Determine the hydraulic conductivity of the permeable layer. Use Eq. (7.49).
Thickness of the aquifer, H = 4.5 m
Piezometric level and radial distance of the first observation well:
h1 = 2.9 m; r1 = 17.8 m
Piezometric level and radial distance of the second observation well:
h2 = 1.8 m; r2 = 8.1 m
Rate of discharge from pumping, q = 0.5 m3/min
Expert Solution & Answer
Want to see the full answer?
Check out a sample textbook solutionStudents have asked these similar questions
Question 2
* A well with a diameter of 0.6 m is constructed in a confined aquifer. The sand aquifer has a uniform
thickness of 15 m, overlain by an impermeable layer with a depth of 35 m. A pumping test was conducted
to determine the coefficient of permeability of the aquifer. The initial piezometric surface was 15 m. below
the ground surface datum of the test well and observation wells. After water was pumped at a rated of
13 liters/sec for several days, water levels in the wells stabilized with the following drawdowns, 6.4 m in
the test well, 3.7 m in the observation well 10 m from the test well, and 2.4 m in the second observation
well at a distance of 30 m. From these data:
o Find the depth of the water in the test well
Calculate the permeability of the aquífer.
The results of a constant-head permeability test for a
sand sample having a sectional area of 10000mm2
and a length of 200 mm are as follows: (1) Constant
head difference 400mm (2) Time of collection of water
= 30 seconds (3) Volume of water collected = 600
cm3. The hydraulic conductivity is:
Oa. 1.0 mm/sec
Ob. 1,7mm/sec
c. 2.9 mm/sec
O d. 0.5mm/sec
1. 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 days
Chapter 7 Solutions
Principles of Geotechnical Engineering (MindTap Course List)
Ch. 7 - Prob. 7.1PCh. 7 - Prob. 7.2PCh. 7 - Prob. 7.3PCh. 7 - Prob. 7.4PCh. 7 - Prob. 7.5PCh. 7 - Prob. 7.6PCh. 7 - Prob. 7.7PCh. 7 - Prob. 7.8PCh. 7 - Prob. 7.9PCh. 7 - Prob. 7.10P
Ch. 7 - Prob. 7.11PCh. 7 - Prob. 7.12PCh. 7 - Prob. 7.13PCh. 7 - Prob. 7.14PCh. 7 - Prob. 7.15PCh. 7 - Prob. 7.16PCh. 7 - Prob. 7.17PCh. 7 - Prob. 7.18PCh. 7 - Prob. 7.19PCh. 7 - Prob. 7.20PCh. 7 - Prob. 7.21PCh. 7 - Refer to Figure 7.24. The following data were...Ch. 7 - Prob. 7.23PCh. 7 - Prob. 7.1CTP
Knowledge Booster
Learn more about
Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, civil-engineering and related others by exploring similar questions and additional content below.Similar questions
- Find out the change in length in a rock mass. while the strain recorded is 3% and the original length of that mass is 4 cm. Q:5 b) How the property of permeability generates in soil and find out the hydraulic conductivity of a rock when change in height is 6 cm and the original height of the sample is 8 cm. the volume recorded in outlet is 20cm^3 in 20 min. the diameter of intact saturated rock mass is 5 cm. *arrow_forwardA confined aquifer is shown in the figure. The aquifer has a hydraulic conductivity of 23 m/day and a void ratio of 0.78. The piezometric heads in the two observation wells L = 2140 m apart are 65 m and 60 m from a common datum. The aquifer has an average depth ot t = 36 m and average width of w = 4.72 km. Recharge 65 Aquifer t L 1. Determine the rate of flow of water through the aquifer, in m3/day. (IN 2 DECIMAL PLACES) 2. Determine the seepage velocity in cm/s. (IN EXPONENTIAL FORM AND IN 2 DECIMAL PLACES) 3. Determine the time of travel in days from the head of the aquifer to a point 3 km downstream. (IN 2 DECIMAL PLACES)arrow_forwardA field sample of an aquifer is packed in a test cylinder. The cylinder has a length of 120 cm and a diameter of 12 cm. The field sample with a porosity of 0.24 is tested under a constant head difference with water at 10°C. If the estimated hydraulic conductivity of the sample is 40 m/day and the hydraulic gradient is 1.5, calculate the average flow velocity (pore velocity). Ply Sand column Datum plane O a. u = 166.63 m/d O b. u = 250.00 m/d O c.u = 200.00 m/d O d. u = 48.00 m/darrow_forward
- Three piezometers have been installed in the confined aquifer shown in Figure 2 below. The aquifer has a uniform thickness of 3.5 m and a hydraulic conductivity of 2x10-1 cm/s. Determine the hydraulic gradient, the direction of flow, the transmissivity, and the flow rate per unit width of the aquifer.arrow_forwardFor a falling-head permeability test, the following values are given: Length of specimen = 200 mm Area of soil specimen = 1000 mm^2 Area of standpipe = 40 mm^2 Head difference at time t = 0 = 500 mm Head difference at timt t = 3 minutes = 300 mm Determine the hydraulic conductivity of the soil in ×10−4cmsec Please answer this asap. For upvote. Thank you very mucharrow_forwardA confined aquifer has hydraulic conductivity of the aquifer, K =50 m/day and 0.2 of porosity. The piezometric head in two wells are 55 m and 50 m, respectively, which 1000 m apart to each other. The average thickness and width of the aquifer are 25 m and 5 km, respectively. Estimate (i) The flowrate through the aquifer. Based on the result, describe the type of layer as shown in TABLE Q5(a) in terms of storability effect. (ii) Time of travel from the head of the aquifer to downstream of 3.5 km by assuming no dispersion or diffusion along the aquifer. Discuss on what would happen if there are dispersion or diffusion occur along the aquifer due to pumping activityarrow_forward
- A falling head hydraulic conductivity test is performed on a sample of soil. The following values are given: Length of specimen = 8 in. • Area of soil specimen = 1.6 in^2 • Area of standpipe = 0.06 in^2 • Head difference at time t=0 = 20 in %3D • Head difference at time t=180 sec = 12 in a. Find the coefficient of permeability of soil b. Compute the rate of flow of water in the soilarrow_forwardA canal is cut into a soil with a stratigraphy shown in Figure A. Assuming flow takes place laterally and vertically through the sides of the canal and vertically below the canal, determine the equivalent hydraulic conductivity in the horizontal and vertical directions. The vertical and horizontal hydraulic conductivities for each layer are assumed to be the same. Calculate the ratio of the equivalent horizontal hydraulic conductivity to the equivalent vertical hydraulic conductivity for flow through the sides of the canal. 1.1 m k = 2.0 × 10-6 cm/sec 1.4 m k = 4.5 × 10-6 cm/sec Canal 3.2 m 2.0 m k = 3.2 × 10-5 cm/sec 1.3 m k = 0.5 × 10-3 cm/sec 3.2 m k = 0.7 × 10-4 cm/secarrow_forwardshown in the figure. The coefficient of permeability of the Water is flowing through the permeability apparatus as coil is k m/s and the porosity of the soil sample is 0.50. 0.4 m Soll 0.8 m 0.4 m The total head, elevation head and pressure head in metres of water at the point R shown in the figure arearrow_forward
- The thickness of a horizontal, confined, homogeneous, isotropic aquifer of infinite areal extent is 30m. A well fully penetrating the aquifer was continuously pumped at a constant rate of 0.1 m³/s for a period of 1 day. The drawdowns given in the table below were observed in a fully penetrating well 90 m from the pumping well. Compute the transmissivity and the storativity by using: a) the Theis method of log-log matching. b) the Cooper-Jacob method of semi-log plotting. [For Part a), you have to first use attached Table to plot the values of W(u) versus 1/u on a log-log graph in the range of 10-9arrow_forward1. (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 Gravelarrow_forward2. A well with a diam. of 0.6 m. is constructed in a confined aquifer as shown. The sand aquifer has a uniform thickness of 15 m. overlain by an impermeable layer with a depth of 35 m. A pumping test was conducted to determine the coefficient of permeability of the aquifer. The initial piezometric surface was 15 m. below the ground surface datum of the test well and observation wells. After water was pumped at a rate of 13 liters/sec. for several days, water levels in the wells stabilized with the following drawdowns, 6.4 m. in the test well, 3.7 m. in the observation well 10 m. from the test well and 2.4 m. in the second observation well at a distance 30 m. From these data, o Find the depth of water in the test well. • Calculate the permeability of the aquifer. O Compute the transmissibility of the impermeable layer. 71-30 Ground surface 20 15m Water Leve intern 72=10 Static water level observation wall -impermeable confined aquifer hi hrarrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
Recommended textbooks for you
- Principles of Geotechnical Engineering (MindTap C...Civil EngineeringISBN:9781305970939Author:Braja M. Das, Khaled SobhanPublisher:Cengage Learning
Principles of Geotechnical Engineering (MindTap C...
Civil Engineering
ISBN:9781305970939
Author:Braja M. Das, Khaled Sobhan
Publisher:Cengage Learning
The Bizarre Paths of Groundwater Around Structures; Author: Practical Engineering;https://www.youtube.com/watch?v=bY1E2IkvQ3k;License: Standard Youtube License