11.18 A 4.5 m saturated clay layer (two-way drainage) subjected to surcharge loading underwent 90% primary consolidation in 180 days. a. Find the coefficient of consolidation of the clay for the pressure range. b. How long will it take for a 19-mm-thick clay specimen to undergo 65% con- solidation in a laboratory test? C

11.18 A 4.5 m saturated clay layer (two-way drainage) subjected to surcharge loading underwent 90% primary consolidation in 180 days. a. Find the coefficient of consolidation of the clay for the pressure range. b. How long will it take for a 19-mm-thick clay specimen to undergo 65% con- solidation in a laboratory test? C

Principles of Foundation Engineering (MindTap Course List)

9th Edition

ISBN:9781337705028

Author:Braja M. Das, Nagaratnam Sivakugan

Publisher:Braja M. Das, Nagaratnam Sivakugan

Chapter2: Geotechnical Properties Of Soil

Section: Chapter Questions

Problem 2.12P

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A clay sample underwent a consolidation test in the lab. The clay specimen has drainage on both sides and a height of 25.4 mm. Assume that the clay sample's preconsolidation pressure was less than 150 kPa prior to the consolidation test. The void ratio was 0.96 when the applied effective vertical pressure was 150 kPa. When the vertical effective pressure increased from 150 to 220 kPa, the void ratio at the end of consolidation and compression was 0.88. It was discovered that the sample needed 3 minutes to consolidate by 30%. Following the consolidation test, a swelling/unloading test was conducted, in which the vertical effective stress was lowered from 220 to 150 kPa and the end-of-swelling void ratio was determined to be 0.9. Required a. The compression index of the clay b. The swelling index of the clay C. The height of the clay sample at the end of compression d. The coefficient of consolidation of the clay e. The final height of the clay sample at the end of swelling
In the laboratory test on a clay sample of thickness 25mm, drained at top only, 50% consolidation occurred in 11 minutes. Assume = 0.197, T = 0.405. Find the time required for the corresponding clay layer in the field of 3m thick and drained at top and bottom to undergo 50% consolidation. Also, find the time required to undergo 70% consolidation. TE %3D 70 50
‹ample 9.1: Following results were recorded from a consolidation test on a specime turated clay, each load being maintained constant for 24 hours before the addition o ext increment.
b. If c, = 2.05 × 10-3 in./sec, determine k in ft/sec corresponding to the average void ratio within the pressure range. 11.17 The time for 75% consolidation of a 25-mm clay specimen (drained at top and bottom) in the laboratory is 22 minutes. How long will it take for a 6-m thick clay layer in the field to undergo 55% consolidation under the same pressure increment? In the field, there is a rock layer at the bottom of the clay.
Refer to the soil profile shown in Figure P2.12. The clay is normally consolidated. A laboratory consolidation test on the clay gave the results: If the average effective stress on the clay layer increase by 50 kN/m2.a. What would be the total consolidation settlement?b. If Cv = 9.36 x 10-4 cm2/sec, how long will it take for half the consolidation settlement to take place?
Two specimens of fully saturated normally consolidated clay were isotropically consolidated to 150 kPa and 300 kPa, after which they had void ratios of 0.74 and 0.64 respectively. (i) Calculate the values of N and i defining the isotropic normal consolidation line for this clay. Hint: Use simultaneous equations.
The laboratory consolidation data for an undisturbed clay specimen are as follows: e1 = 1.12 P₁ = 90 kPa e2 = 0.90 P2 = 450 kPa 1. Compute the value of the compression index. 2. Compute the value of the swell index assuming it is equal to 1/6 the value of the compression index. 3. Compute the void ratio for a pressure of 600 kPa. 4. Compute the coefficient of compressibility. 5. Compute the value of the coefficient of volume compressibility.
A 3m thick layer of saturated clay (two-way drainage) under a surcharge loading underwent 90% primary consolidation in 100 days. The laboratory test's specimen will have two-way drainage. Find the coefficient of consolidation of clay for the pressure range in cm^2/sec, (T_90 = 0.848)
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 site is underlain by a saturated clay layer with thickness = 5m. A sample extracted from the center of the clay layer was recently tested for consolidation parameters. The results indicate that the compression index is 0.33, the recompression index is 0.09, and the void ratio is 1.2. The results also indicate that the layer is normally consolidated. Calculate the preconsolidation stress of the clay. Express your answer in kPa. Note: this is a short problem; read the problem statement carefully. Use unit water weight = 10 kN/m3.
The layer is subjected to a uniform vertical stress increase of 100 kPa. The singly-drained clay layer has a coefficient of consolidation of 20 ft2 /yr. Determine the value of the excess pore pressure at point A 2 years after the application of the load. Also given is the chart giving the local degree of consolidation. a)4.4 kPa b)44 kPa c)88 kPa d)96 kPa
A 3.75m clay layer in the field (drained on one side) is normally consolidated. When the pressure is increased from 50 kPa to 150 kPa, the void ratio decreases from 0.9 to 0.75. The coefficient of permeability of the clay was 6 x 10^-7 cm/s.• How long (days) will it take to reach 50% consolidation?• What is the settlement when the soil reaches 50% consolidation?Final answer should be in 3 decimal places.