A fine-grained (silty-clay) soil is required for the core of a rockfill dam. The permeability tests are performed on two types of soil. The diameter (D) of the specimen was 8 cm, length (L) between the measuring points was 15 cm. the following table shows the recorded data during the test for both the soils. Soil A B Head difference, h (cm) 12 15 Volume of water, V (cm3) 10 8 Time, t (sec) 300 350 Compute the hydraulic conductivity (k) by applying Darcy’s Law and select the best soil. Give reasons for the answer.

A fine-grained (silty-clay) soil is required for the core of a rockfill dam. The permeability tests are performed on two types of soil. The diameter (D) of the specimen was 8 cm, length (L) between the measuring points was 15 cm. the following table shows the recorded data during the test for both the soils. Soil A B Head difference, h (cm) 12 15 Volume of water, V (cm3) 10 8 Time, t (sec) 300 350 Compute the hydraulic conductivity (k) by applying Darcy’s Law and select the best soil. Give reasons for the answer.

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter4: Plasticity And Structure Of Soil

Section: Chapter Questions

Problem 4.8P

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A fine-grained (silty-clay) soil is required for the core of a rockfill dam. The permeability tests are performed on two types of soil. The diameter (D) of the specimen was 8 cm, length (L) between the measuring points was 15 cm. the following table shows the recorded data during the test for both the soils. Soil A B Head difference, h (cm) 12 15 Volume of water, V (cm³) 10 8 Time, t (sec) 300 350 Compute the hydraulic conductivity (k) by applying Darcy's Law and select the best soil.
A constant head permeability test is performed on soil that is 2 cm x 2 cm square, and 2.5cm long. The head difference applied during the test is 20 cm and 7 cm3 is collected over a time of 100 sec. Provide step by step solution. a) Compute the permeability based on these test conditions and results. b) A falling head test is conducted on the same soil specimen at the same time (t1 – t2 = 100 sec), and the standpipe diameter is 0.8 cm. If the average head during the test should be 18 cm, what are h1 and h2 values, provide step by step solution solving h1 and h2 values.
Afalling-head permeability test is performed on a fine-grained soil. The soil sample has a length of 120 mm and a cross-sectional area of 600 mm2. The water in the standpipe flowing into the soil is 0.60 m above the top of the sample at the start of the test. It falls 50 mm in 30 minutes. The standpipe has a cross-sectional area of 200 mm2. (a) Make a sketch of the described conditions. (b) What is the coefficient of permeability in millimeters per second? (c) What is the coefficient of permeability in feet per minute? (d) On the basis of the calculated value for khyd, what is the probable soil type?
In a falling permeameter, the sample used is 20 cm long having a cross-sectional area of 24 cm2. The sample of soil is made of three layers. The thickness of the first layer from the top is 8 cm and has a value of k1 = 2 x 10-4 cm/s, the second layer of thickness 6 cm has k2 = 5 x 10-4 cm/s and the bottom layer of thickness 4 cm has k3 = 7 x 10-4 cm/s. Assume the flow is taking perpendicular to the layers. Estimate the average hydraulic conductivity of soil in the vertical direction. a.3.12 x 10-4 cm/s b.5.69 x 10-4 cm/s c.2.35 x 10-4 cm/s d.4.28 x 10-4 cm/s e.6.69 x 10-4 cm/s
A clay sample was consolidated in a triaxial cell under a backpressure of 50 kPa and cell pressure of 150 kPa. The drainage valve was then closed and the cell pressure was increased to 200 kPa when the pore pressure increased to 98 kPa. What is Skepton’s B-parameter? The above sample was then subjected to a vertical deviator stress, which was increased from zero under undrained conditions. The sample failed when the pore water pressure was 160 kPa and the deviator stress was 70 kPa. What is Skempton’s A-parameter at failure? Assuming the clay is normally consolidated, find the friction angle in terms of effective stresses.
A clay sample was consolidated in a triaxial cell under a backpressure of 50 kPa and cell pressure of 150 kPa. The drainage valve was then closed and the cell pressure was increased to 200 kPa when the pore pressure increased to 98 kPa. What is Skempton’s B-parameter? The above sample was then subjected to a vertical deviator stress, which was increased from zero under undrained conditions. The sample failed when the pore water pressure was 160 kPa and the deviator stress was 70 kPa. What is Skempton’s A-parameter at failure? Assuming the clay is normally consolidated, find the friction angle in terms of effective stresses.
In a falling head permeability test on a soil sample of length L1, the head of water in the stand pipe takes 60 seconds to fall from 900 mm to 135 mm above the tail water level. When another soil sample of same length 50 mm is placed on the first soil sample, the time taken for the head to fall between the same limits is 140 seconds. The soil sample has a cross-sectional area of 4560 mm2 and a stand pipe has an area of 130 mm2. The permeability of the second soil sample will be
In falling head permeability test the initial head was 350 mm and the final head was 60 mm. The cross-sectional area of the burette was 200 mm2. The sample was 50 mm in diameter and 105 mm long. If the test took 8 hours and 30 minutes, what was the coefficient of permeability of the soil in m/s?
In a falling permeameter, the sample used is 20 cm long having a cross sectional area of 24 cm2. The sample of soil is made of three layers. The thickness of the first layer from the top is 8 cm and has a value of k1 = 2 x 10-4 cm/s, the second layer of thickness 6 cm has k2 = 5 x 10-4 cm/s and the bottom layer of thickness 4 cm has k3 = 7 x 10-4 cm/s. Assume the flow is taking perpendicular to the layers. Calculate the time required for the drop of head from 25 to 12 cm if the cross sectional area of the stand pipe is 2 cm2. a.71.5 min b.62.9 min c.87.8 min d.66.7 min e.58.81 min
A consolidated-undrained tri-axial test was conducted on a normally conslidated clay sample and the results are follows: Chamber confining pressure= 119kpa Deviator Stress at failure=90 kpa Pore water pressure= 58kpa These results were used to determine the drained friction angle of the soil. Compute the deviator stress (kpa) at failure when the drained test was conducted with the chamber confining pressure changed to 156 kpa. Use stored value. Answer to 5 decimal places.
FUNDAMENTALS OF GEOTECHNICAL ANALYSIS A constant head permeability test is performed on soil that is 2 cm x 2 cm square, and 2.5cm long. The head difference applied during the test is 20 cm and 7 cm3 is collected over a time of 100 sec. Provide step by step solution. a) Compute the permeability based on these test conditions and results. b) A falling head test is conducted on the same soil specimen at the same time (t1 – t2 = 100 sec), and the standpipe diameter is 0.8 cm. If the average head during the test should be 18 cm, what are h1 and h2 values?
A falling head permeability test was carried out on a 15cm long of silty clay. The diameter of the sample and the stand pipe were 9.8cm and 0.75cm respectively. The water level in the stand pipe was observed to fall from 7ocm to 45cm in 12minutes. Determine the coefficient of permeability of the soil in m/day and the height of water level in stand pipe after 20minutes.