The 1D consolidation test result is depicted in Fig. 1. The test was conducted o
ID: 1710091 • Letter: T
Question
The 1D consolidation test result is depicted in Fig. 1. The test was conducted on an undisturbed clay sample taken from a depth of 10 m below the soil surface. Ground water table is located at the soil surface and saturated unit weight of clay is 19.62 kPa. a) Determine the preconsolidation pressure of this sample by using the procedure described on page 439 of your textbook. b) Determine the overconsolidation ratio (OCR) of the sample tested. c) Is this sample normally consolidated or overconsolidated?Explanation / Answer
(1)Effective stress at site = total stress - pore water pressure = 19.62*10 - 9.81*10 = 98.1 kPa
So, preconsolidation pressure = 98.1 kPa, which is also evident from the graph itself.
(2) OCR = 1, because the current highest stress is somewhere greater than 1000 kPa. It is treated as overconsolidated until the stress is less than 98.1 kPa.
(3) This sample is overconsolidated untill stress reaches preconsolidation pressure i.e. 98.1kPa, after than it is normally consolidated.
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