A 40 mm thick clay specimen is set up in an hydraulic oedometer apparatus with 2-way...

 

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A 40 mm thick clay specimen is set up in an hydraulic oedometer apparatus with 2-way drainage. The applied vertical stress is to be raised by 100 kPa as part of a standard test to determine c, and Ce for the clay. The laboratory technician is in a hurry and decides to speed up the test by using a stress ramp for 18 minutes (0.3 hours) as shown in Figure 1 below. (a) Use a numerical method to determine the variation of excess pore pressure and compression of the specimen as a function of time when the clay has properties m = 0.0005 m²/kN and cv = 5.3333 mm²/min. (b) By varying the stress ramp and its duration determine the fastest time to achieve within 1% of the expected final compression (c) Explore the effect on these responses of varying B, the number of layers and the time step (d) Would you expect the use of the stress ramp to produce reliable values of cv and Ce Stress (kPa) 250 200 150 100 50 0.2 0.4 Time (hours) 0.6 0.8 A 40 mm thick clay specimen is set up in an hydraulic oedometer apparatus with 2-way drainage. The applied vertical stress is to be raised by 100 kPa as part of a standard test to determine c, and Ce for the clay. The laboratory technician is in a hurry and decides to speed up the test by using a stress ramp for 18 minutes (0.3 hours) as shown in Figure 1 below. (a) Use a numerical method to determine the variation of excess pore pressure and compression of the specimen as a function of time when the clay has properties m = 0.0005 m²/kN and cv = 5.3333 mm²/min. (b) By varying the stress ramp and its duration determine the fastest time to achieve within 1% of the expected final compression (c) Explore the effect on these responses of varying B, the number of layers and the time step (d) Would you expect the use of the stress ramp to produce reliable values of cv and Ce Stress (kPa) 250 200 150 100 50 0.2 0.4 Time (hours) 0.6 0.8

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Answer a To determine the variation of excess pore pressure and compression of the specimen as a function of time we need to use a numerical method The numerical method used in this case is the Finite ... View the full answer