2. A layer of compressible clay 6m thick overlies an impervious bedrock and carries an overburden of pervious sand. A large structure founded in the sand causes the stress on every horizontal section of the clay to increase to the same value. In a standard laboratory oedometer consolidation test performed on a 19 mm thick clay specimen, the void ratio changed from 0.765 to 0.750 under a corresponding increase in stress. Consolidation was 70% complete after 30 min. In the field, a) Estimate the settlement of the structure. b) Determine the time taken for one half of the consolidation settlement to take place (Remember the lab test is for a doubly drained specimen.). c) Determine how long it takes for 50% of the settlement to take place at a depth of 0, 2, 3, 5 and 6 m of the clay stratum. d) If the clay were underlain by pervious sand, determine how long it takes for 50% of the settlement to take place at a depth of 0, 2, 3, 5 and 6 m of the clay stratum.

2. A layer of compressible clay 6m thick overlies an impervious bedrock and carries an overburden of pervious sand. A large structure founded in the sand causes the stress on every horizontal section of the clay to increase to the same value. In a standard laboratory oedometer consolidation test performed on a 19 mm thick clay specimen, the void ratio changed from 0.765 to 0.750 under a corresponding increase in stress. Consolidation was 70% complete after 30 min. In the field, a) Estimate the settlement of the structure. b) Determine the time taken for one half of the consolidation settlement to take place (Remember the lab test is for a doubly drained specimen.). c) Determine how long it takes for 50% of the settlement to take place at a depth of 0, 2, 3, 5 and 6 m of the clay stratum. d) If the clay were underlain by pervious sand, determine how long it takes for 50% of the settlement to take place at a depth of 0, 2, 3, 5 and 6 m of the clay stratum.

Principles of Geotechnical Engineering (MindTap Course List)

9th Edition

ISBN:9781305970939

Author:Braja M. Das, Khaled Sobhan

Publisher:Braja M. Das, Khaled Sobhan

Chapter12: Shear Strength Of Soil

Section: Chapter Questions

Problem 12.20P

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Similar questions

A 75 mm diameter clay specimen was consolidated in an oedometer under 200 kPa. At the end of consolidation, the void ratio is 0.863 and the specimen thickness is 18.51 mm. When the stress increment of 200 was added to the current vertical stress of 200 kPa, the specimen consolidated to a thickness of 17.56 mm. Assuming that the clay was normally consolidated under the vertical stress of 200 kPa, find the a) coefficient of volume compressibility in (MPa)^-1 and rounded to the 3rd decimal place.b) and the compression index of the clay rounded to the 2nd decimal place.
A consolidated undrained triaxial test was performed on a normally consolidated clay with a critical state friction angle of 230. After an initial isotropic consolidation at a cell pressure of 50 kPa, drainage was turned off, the cell pressure was increased to 85 kPa, and the sample was loaded to ultimate conditions. A pore pressure of 55 kPa was measured at ultimate state. What value of major principal total stress was measured at the ultimate state?
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]?
a）For clays, the failure line (one that connects the peak failure stresses) in the normally consolidated range does not have a cohesion intercept, whereas the failure line in the overconsolidated range has a cohesion intercept. T or F B）During the shearing phase of a CU test, the void ratio of a NC consolidated clay specimen will: 1 decrease. 2 could increase or decrease. 3 remain a constant. 4 increase. C)What does the cohesion (that appears in the Mohr-Coulomb criterion) of OC clays depend on? 1the preconsolidation pressure. 2whether the failure stresses are total or effective. 3the soil type. 4everything listed here.
A saturated clay sample in an oedometer is under vertical pressure of 120 kPa and is at a normally consolidated state. The void ratio and the sample height at this stage are 1.21 and 18.40 mm respectively. When the vertical stress was increased to 240 kPa at the end of the consolidation, the thickness of the sample was reduced to 16.80 mm. When the vertical pressure was reduced to the original value of 120 kPa, the sample heaved to a thickness of 16.95 mm. Estimate both the compression index and recompression index of the clay. What would be the reduction in thickness from now if the vertical pressure was increased by 200 kPa? What is the average coefficient volume compressibility during this pressure increment?
A 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 clay