Concept explainers
Find the pore water pressure at failure for the second specimen.
Find the Skempton’s pore pressure parameter at failure.
Answer to Problem 10.13P
The pore water pressure at failure for the second specimen is
The Skempton’s pore pressure parameter at failure is
Explanation of Solution
Given information:
Specimen 1:
The confining pressure of the clay
The deviator stress at failure
Specimen 2:
The confining pressure of the clay for consolidated undrained triaxial test is
The deviator stress at failure
Calculation:
The consolidated drained triaxial test was conducted for normally consolidated clay (specimen 1) and the consolidated undrained triaxial test was conducted for specimen 2.
Consider the consolidated drained triaxial test (specimen 1).
Find the major principal effective stress at failure
Here,
Substitute
Find effective friction angle
Here,
Consider that the specimen as normally consolidated clay. Hence the effective stress cohesion
Substitute 0 for
Rearrange the Equation.
Substitute
Consider the consolidated undrained triaxial test (specimen 2).
Find the major principal stress
Here,
Substitute
Show the formula for major principal effective stress.
Here,
Substitute
Show the formula for minor principal effective stress.
Substitute
Calculate the pore water pressure using the Equation (1).
Substitute Equation (2), (3) in Equation (1) and
Therefore, the pore water pressure at failure for specimen 2 is
Find the Skempton’s pore pressure parameter
Substitute
Therefore, the Skempton’s pore pressure parameter at failure is
Want to see more full solutions like this?
Chapter 10 Solutions
Fundamentals of Geotechnical Engineering (MindTap Course List)
- A consolidated drained (CD) triaxial test was carried out on a normally consolidated clay. The specimen was consolidated under a cell pressure of 100 kPa and back pressure of 30 kPa. The axial deviatoric stress was increased very slowly to failure, so that there was no excess pore water pressure developed during the shearing. The specimen failed under a deviatoric stress of 130 kPa. The back pressure of 30 kPa was maintained throughout the test. (i) What is the friction angle in terms of effective stresses? (ii) What are the shear stress and normal stress acting on the failure plane? Solution fast pleasearrow_forwardA consolidated drained (CD) triaxial test was carried out on a normally consolidated clay. The specimen was consolidated under a cell pressure of 100 kPa and back pressure of 30 kPa. The axial deviatoric stress was increased very slowly to failure, so that there was no excess pore water pressure developed during the shearing. The specimen failed under a deviatoric stress of 130 kPa. The back pressure of 30 kPa was maintained throughout the test. (1) What is the friction angle in terms of effective stresses? (ii) What are the shear stress and normal stress acting on the failure plane?arrow_forwardA consolidated-undrained triaxial compression test was performed on a normalconsolidated clay sample. During the experiment, the confining pressure was 140 kPa, thedeviator stress was 125 kPa, and the pore water pressure was 75 kPa at the time of failure.According to the information given:i- Find the consolidated-undrained internal friction angle of the clay. ii- Find the drained friction angle of the clayarrow_forward
- A consolidated-drained triaxial test was conducted on a normally consolidated clay. The results were as follows: Determine: a. Angle of friction, f? b. Angle u that the failure plane makes with the major principal plane c. Normal stress, s?, and shear stress, tf , on the failure planearrow_forwardA triaxial shear test was performed on a well-drained sand sample. The normal stress on the failure plane and the shear stress on the failure plane, at failure were determined to be 6100 psf and 4600 psf, respectively. a. Determine the angle of internal friction of the sand? b. Determine the angle of the failure plane? c. Determine the maximum principal stress? Please answer this asap. For upvote. Thank you very mucharrow_forward2. A triaxial shear test was performed on a well-drained sand sample. The normal stress on the failure plane and the shear stress on the failure plane, at failure was determined to be 6,300 psf and 4,200 psf, respectively. a. Determine the angle of internal friction of the sand. b. Determine the angle of failure plane. c. Determine the maximum principal stress.arrow_forward
- In a triaxial test, a specimen of saturated [normally consolidated] clay was consolidated under a chamber confining pressure of 80 kPa. The axial stress on the specimen was then increased through the allowing the drainage from the specimen. The specimen fails when 120 kPa. The pore water pressure at the time was 50 kPa. What is the consolidated undrained friction angle [phi]?arrow_forwardA consolidated-undrained test determines that the shear strength of a normally consolidated clay is given by τf = σ’tan 27o. The confining pressure is 150 kPa, and deviator stress at failure is 120 kPa.• Find the consolidated-undrained friction angle• Pore water pressure developed in the specimen at failureFinal answer should be in 3 decimal places.arrow_forward• In consolidated-drained triaxial test on a normally consolidated clay, the specimen failed at a deviator stress of 124 KN/sq.m. If the effective stress friction angle is known to be 31°, what was the effective confining pressure at failure?arrow_forward
- 5. A consolidated, undrained triaxial test is being caried out on a normally consolidated clay where c = 0 and 41= 26'. The triaxial specimen was consolidated under a cell pressure of 300 kPa and backpressure of 80 kPa. Skempton's A parameter at failure is estimated to be 0.80. The drainage valve has since been dosed and the vertical deviator stress increased to failure. What would be the deviator stress and pore water pressure at failure?arrow_forwardA consolidated-undrained triaxial test was conducted on a saturated, normally consolidated clay. The test results areσ3 = 13 lb/in2σ1(failure) = 32 lb/in2Pore pressure at failure = u = 5.5 lb/in2. Determine c, Φ, c', and Φ'.arrow_forwardData from an oedometer test using a clay specimen are plotted in the graph shown below. If the compression index is equal to 0.6, calculate the void ratio (e2) missing at Point C, which is associated with a vertical effective stress equal to 105 kPaarrow_forward
- Principles of Geotechnical Engineering (MindTap C...Civil EngineeringISBN:9781305970939Author:Braja M. Das, Khaled SobhanPublisher:Cengage LearningFundamentals of Geotechnical Engineering (MindTap...Civil EngineeringISBN:9781305635180Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage LearningPrinciples of Foundation Engineering (MindTap Cou...Civil EngineeringISBN:9781337705028Author:Braja M. Das, Nagaratnam SivakuganPublisher:Cengage Learning
- Principles of Foundation Engineering (MindTap Cou...Civil EngineeringISBN:9781305081550Author:Braja M. DasPublisher:Cengage Learning